Spintronics Paper

Spintronics

Spintronics

1. Introduction:

Conventional electronic devices rely on the transport of electrical charge carriers –electrons in a

semiconductor such as silicon. Now, however, physicists are trying to exploit the ‘spin’ of the

electron rather than its charge to create a remarkable new generation of ‘spintronic’ devices

which will be smaller, more versatile and more robust than those currently making up silicon

chips and circuit elements.

Imagine a data storage device of the size of an atom working at a speed of light. Imagine a

computer memory thousands of times denser and faster than today’s memories and also imagine

a scanner technique which can detect cancer cells even though they are less in number. The

above-mentioned things can be made possible with the help of an exploding science –

“Spintronics”.

Spintronics is a technology which deals with spin dependent properties of an electron instead of

or in addition to its charge dependent properties. Conventional electronics devices rely on the

transport of electric charge carries-electrons. But there is other dimensions of an electron other

than its charge and mass i.e. spin. This dimension can be exploited to create a remarkable

generation of spintronic devices. It is believed that in the near future spintronics could be more

revolutionary than any other technology.

As there is rapid progress in the miniaturization of semiconductor electronic devices leads to a

chip features smaller than 100 nanometers in size, device engineers and physicists are inevitable

faced with a looming presence of a quantum property of an electron known as spin, which is

closely related to magnetism. Devices that rely on an electron spin to perform their functions

form the foundations of spintronics.

Information-processing technology has thus far relied on purely charge based devices ranging

from the now quantum, vacuum tube today’s million transistor microchips. Those conventional

electronic devices move electronic charges around, ignoring the spin that tags along that side on

each electron.

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2. Basic Principle:

The basic principle involved is the usage of spin of the electron in addition to mass and charge of

electron. Electrons like all fundamental particles have a property called spin which can be

orientated in one direction or the other – called ‘spin-up’ or ‘spin-down’ –like a top spinning

anticlockwise or clockwise. Spin is the root cause of magnetism and is a kind of intrinsic angular

momentum that a particle cannot gain or lose. The two possible spin states naturally represent

‘0’and ‘1’in logical operations. Spin is the characteristics that makes the electron a tiny magnet

complete with north and south poles .The orientation of the tiny magnet ‘s north-south poles

depends on the particle’s axis of spin.

Fundamentals of spin:

1. In addition to their mass, electrons have an intrinsic quantity of angular momentum

called spin, almost of if they were tiny spinning balls.

2. Associated with the spin is magnetic field like that of a tiny bar magnet lined up with

the spin axis

.

Fig.1. Electron spinning

3. Scientists represent the spin with a vector. For a sphere spinning “west to east”, the

vector points “north” or “up”. It points “south” or “down” for the spin from “east to

west”.

4. In a magnetic field, electrons with “spin up” and “spin down” have different energies.

5. In an ordinary electronic circuit the spins are oriented at random and have no effect

on current flow.

6. Spintronic devices create spin-polarized currents and use the spin to control current

flow.

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Imagine a small electronically charged sphere spinning rapidly. The circulating charges in the

sphere amount to tiny loops of electric current which creates a magnetic field. A spinning sphere

in an external magnetic field changes its total energy according to how its spin vector is aligned

with the spin. In some ways, an electron is just like a spinning sphere of charge, an electron has a

quantity of angular momentum (spin) an associated magnetism. In an ambient magnetic field and

the spin changing this magnetic field can change orientation. Its energy is dependent on how its

spin vector is oriented. The bottom line is that the spin along with mass and charge is defining

characteristics of an electron. In an ordinary electric current, the spin points at random and plays

no role in determining the resistance of a wire or the amplification of a transistor circuit.

Spintronic devices in contrast rely on the differences in the transport of spin-up and spin-down

electrons.

3. Giant Magneto Resistance:

Magnetism is the integral part of the present day’s data storage techniques. Right from the

Gramophone disks to the hard disks of the super computer magnetism plays an important role.

Data is recorded and stored as tiny areas of magnetized iron or chromium oxide. To access the

information, a read head detects the minute changes in magnetic field as the disk spins

underneath it. In this way the read heads detect the data and send it to the various succeeding

circuits.

The effect is observed as a significant change in the electrical resistance depending on whether

the magnetization of adjacent ferromagnetic layers are in a parallel or anantiparallel alignment.

The overall resistance is relatively low for parallel alignment and relatively high for antiparallel

alignment.

The magneto resistant devices can sense the changes in the magnetic field only to a small extent,

which is appropriate to the existing memory devices. When we reduce the size and increase data

storage density, we reduce the bits, so our sensor also has to be small and maintain very, very

high sensitivity. The thought gave rise to the powerful effect called “Giant Magnetoresistance”

(GMR). GMR is a quantum mechanical magnetoresistance effect observed in thin film structures

composed of alternating ferromagnetic and non magnetic layers. The 2007 Nobel Prize in

physics was awarded to Albert Fert and Peter Grünberg for the discovery of GMR.

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Giant magnetoresistance (GMR) came into picture in 1988, which lead the rise of spintronics. It

results from subtle electron-spin effects in ultra-thin ‘multilayer’ of magnetic materials, which

cause huge changes in their electrical resistance when a magnetic field is applied. GMR is 200

times stronger than ordinary magnetoresistance. It was soon realized that read heads

incorporating GMR materials would be able to sense much smaller magnetic fields, allowing the

storage capacity of a hard disk to increase from 1 to 20 gigabits.

3.1 Construction of GMR:

The basic GMR device consists of a three-layer sandwich of a magnetic metal such as cobalt

with a nonmagnetic metal filling such as silver. Current passes through the layers consisting of

spin-up and spin-down electrons. Those oriented in the same direction as the electron spins in a

magnetic layer pass through quite easily while those oriented in the opposite direction are

scattered. If the orientation of one of the magnetic layers can easily be changed by the presence

of a magnetic field then the device will act as a filter, or ‘spin valve’, letting through more

electrons when the spin orientations in the two layers are the same and fewer when orientations

are oppositely aligned. The electrical resistance of the device can therefore be changed

dramatically. In an ordinary electric current, the spin points at random and plays no role in

determining the resistance of a wire or the amplification of a transistor circuit. Spintronic devices

in contrast, rely on differences in the transport of “spin up” and “spin down” electrons. When a

current passes through the Ferro magnet, electrons of one spin direction tend to be obstructed.

A ferromagnet can even affect the flow of a current in a nearby nonmagnetic metal. For example,

in the present-day read heads in computer hard drives, wherein a layer of a nonmagnetic metal is

sandwiched between two ferromagnetic metallic layers, the magnetization of the first layer is

fixed, or pinned, but the second ferromagnetic layer is not. As the read head travels along a track

of data on a computer disk, the small magnetic fields of the recorded 1’s and 0`s change the

second layer’s magnetization back and forth parallel or antiparallel to the magnetization of the

pinned layer. In the parallel case, only electrons that are oriented in the favored direction flow

through the conductor easily. In the antiparallel case, all electrons are impeded. The resulting

changes in the current allow GMR read heads to detect weaker fields than their predecessors; so

that data can be stored using more tightly packaged magnetized spots on a disk.

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GMR has triggered the rise of a new field of electronics called spintronics which has been used

extensively in the read heads of modern hard drives and magnetic sensors. A hard disk storing

binary information can use the difference in resistance between parallel and antiparallel layer

alignments as a method of storing 1s and 0s.

A high GMR is preferred for optimal data storage density. Current perpendicular-to-plane

(CPP) Spin valve GMR currently yields the highest GMR. Research continues with older

current-in-plane configuration and in the tunnelling magnetoresistance (TMR) spin valves which

enable disk drive densities exceeding 1 Terabyte per square inch.

Hard disk drive manufacturers have investigated magnetic sensors based on the colossal

magnetoresistance effect (CMR) and the giant planar Hall effect. In the lab, such sensors have

demonstrated sensitivity which is orders of magnitude stronger than GMR. In principle, this

could lead to orders of magnitude improvement in hard drive data density. As of 2003, only

GMR has been exploited in commercial disk read-and-write heads because researchers have not

demonstrated the CMR or giant planar hall effects at temperatures above 150K.

Magnetocoupler is a device that uses giant magnetoresistance (GMR) to couple two electrical

circuits galvanicly isolated and works from AC down to DC.

Vibration measurement in MEMS systems.

Detecting DNA or protein binding to capture molecules in a surface layer by measuring the stray

field from superparamagnetic label particles.

4. Spintronic Devices:

Spintronic devices are those devices which use the Spintronic technology. Spintronic-devices

combine the advantages of magnetic materials and semiconductors. They are expected to be non-

volatile, versatile, fast and capable of simultaneous data storage and processing, while at the

same time consuming less energy. Spintronic-devices are playing an increasingly significant role

in high-density data storage, microelectronics, sensors, quantum computing and bio-medical

applications, etc.

Some of the Spintronic devices are

Magnetoresistive Random Access Memory(MRAM)

Spin Transistor

Quantum Computer

Spintronic Scanner

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4.1 MRAM (Magnetoresistive Random access Memory)

An important spintronic device, which is supposed to be one of the first spintronic devices that

have been invented, is MRAM.

Unlike conventional random-access, MRAMs do not lose stored information once the power is

turned off...A MRAM computer uses power, the four page e mail will be right there for you.

Today pc use SRAM and DRAM both known as volatile memory. They can store information

only if we have power. DRAM is a series of

Capacitors, a charged capacitor represents 1 where as an uncharged capacitor represents 0. To

retain 1 you must constantly feed the capacitor with power because the charge you put into the

capacitor is constantly leaking out.

MRAM is based on integration of magnetic tunnel junction (MJT). Magnetic tunnel junction is a

three-layered device having a thin insulating layer between two metallic ferromagnets. Current

flows through the device by the process of quantum tunneling; a small number of electrons

manage to jump through the barrier even though they are forbidden to be in the insulator. The

tunneling current is obstructed when the two ferromagnetic layers have opposite orientations and

is allowed when their orientations are the same. MRAM stores bits as magnetic polarities rather

than electric charges. When a big polarity points in one direction it holds1, when its polarity

points in other direction it holds 0. These bits need electricity to change the direction but not to

maintain them. MRAM is non volatile so, when you turn your computer off all the bits retain

their 1`s and 0`s.

4.2 Spin Transistor

In these devices a non magnetic layer which is used for transmitting and controlling the spin

polarized electrons from source to drain plays a crucial role. For functioning of this device first

the spins have to be injected from source into this non-magnetic layer and then transmitted to the

collector. These non-magnetic layers are also called as semimetals, because they have very large

spin diffusion lengths. The injected spins which are transmitted through this layer start

precessing as illustrated in Figure 1 before they reach the collector due to the spin-orbit coupling

effect.

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Fig. 2 Spin polarized field effect transistor.

Vg is the gate voltage. When Vg is zero the injected spins which are transmitted through the

2DEG layer starts processing before they reach the collector, thereby reducing the net spin

polarization. Vg is the gate voltage. When Vg >> 0 the precession of the electrons is controlled

with electric filed thereby allowing the spins to reach at the collector with the same polarization.

Hence the net spin polarization is reduced. In order to solve this problem an electric field is

applied perpendicularly to the plane of the film by depositing a gate electrode on the top to

reduce the spin-orbit coupling effect as illustrated in Figure 4. By controlling the gate voltage

and polarity can the current in the collector can be modulated there by mimicking the MOSFET

of the conventional electronics. Here again the problem of conductivity mismatch between the

source and the transmitting layer is an important issue. The interesting thing would be if a

Heusler alloy is used as the spin source and a semimetallic Heusler alloy as the transmitting

layer, the problem of conductivity mismatch may be solved. For example from the Slater-Pauling

curve Mt = Zt - 24, Heusler alloys with Mt >>0 can act as spin sources and alloys with Mt ~ 0

can act as semimetals. Since both the constituents are of same structure the possibility of

conductivity mismatch may be less.

Traditional transistors use on-and-off charge currents to create bits—the binary zeroes and ones

of computer information. “Quantum spin field effect” transistor will use up-and-down spin states

to generate the same binary data. One can think of electron spin as an arrow; it can point upward

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Vgg

SourceCollector gate

InAlAs

InGaAs

Spintronics

or downward; “spin-up and spin-down can be thought of as a digital system, representing the

binary 0 and 1. The quantum transistor employs also called “spin-flip” mechanism to flip an up-

spin to a downspin, or change the binary state from 0 to 1.

One proposed design of a spin FET (spintronic field-effect transistor) has a source and a drain,

separated by a narrow semi conducting channel, the same as in a conventional FET.

In the spin FET, both the source and the drain are ferromagnetic. The source sends spin-

polarized electrons in to the channel, and this spin current flow easily if it reaches the drain

unaltered (top). A voltage applied to the gate electrode produces an electric field in the channel,

which causes the spins of fast-moving electrons to process, or rotate (bottom). The drain impedes

the spin current according to how far the spins have been rotated. Flipping spins in this way takes

much less energy and is much faster than the conventional FET process of pushing charges out

of the channel with a larger electric filed.

One advantage over regular transistors is that these spin states can be detected and altered

without necessarily requiring the application of an electric current. This allows for detection

hardware that are much smaller but even more sensitive than today's devices, which rely on

noisy amplifiers to detect the minute charges used on today's data storage devices. The potential

end result is devices that can store more data in less space and consume less power, using less

costly materials. The increased sensitivity of spin transistors is also being researched in creating

more sensitive automotive sensors, a move being encouraged by a push for more

environmentally-friendly vehicles

A second advantage of a spin transistor is that the spin of an electron is semi-permanent and can

be used as means of creating cost-effective non volatile solid state storage that does not require

the constant application of current to sustain. It is one of the technologies being explored for

Magnetic Random Access Memory (MRAM)

Spin transistors are often used in computers for data processing. They can also be used to

produce a computer's random access memory and are being tested for use in magnetic RAM.

This memory is superfast and information stored on it is held in place after the computer is

powered off, much like a hard disk.

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Electronic Devices Spintronic devices

1. Based on properties of charge of the electron 1. Based on intrinsic property spin of electron

2. Classical property 2. Quantum property

3. Controlled by an external electric field in

modern electronics

3. Controlled by external magnetic field

4. Materials: conductors and semiconductors 4.Materials: ferromagnetic materials

5. Based on the number of charges and their

energy

5. Two basic spin states; spin-up and spin-down

6. Speed is limited and power dissipation is high6. Based on direction of spin and spin coupling,

high speed

4.3 Quantum Computer:

A quantum computer is a device for computation that makes direct use of quantum mechanical

phenomena, such as superposition and entanglement, to perform operations on data. Quantum

computers are different from traditional computers based on transistors. The basic principle

behind quantum computation is that quantum properties can be used to represent data and

perform operations on these data. A theoretical model is the quantum Turing machine, also

known as the universal quantum computer.

Although quantum computing is still in its infancy, experiments have been carried out in which

quantum computational operations were executed on a very small number of qubits (quantum

bits). Both practical and theoretical research continues, and many national government and

military funding agencies support quantum computing research to develop

quantum computers for both civilian and national security purposes, such as cryptanalysis.

If large-scale quantum computers can be built, they will be able to solve certain problems much

faster than any current classical computers. All problems solvable with a quantum computer can

also be solved using a traditional computer given enough time and resources.

In a quantum computer, the fundamental unit of information (called a quantum bit or qubit), is

not binary but rather more quaternary in name. This qubit property arises as a direct consequence

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of its adherence to the laws of quantum mechanics. A qubit can exist not only in a state

corresponding to the logical state 0 or 1 as in a classical bit, but also in states corresponding to a

blend or superposition of these classical states. In other words, a qubit can exist as a zero, a one

or simultaneously as both 0 and 1, with a numerical coefficient representing the probability for

each state.

Each electron spin can represent a bit; for instance, a 1 for spin up and 0 for spin down. With

conventional computers, engineers go to great lengths to ensure that bits remain in stable, well-

defined states. A quantum computer, in contrast, lies on encoding information within quantum

bits, or qubits, each of which can exist in a superposition of 0 and 1. By having a large number of

qubits in superposition of alternative states, a quantum computer intrinsically contains a massive

parallelism. Unfortunately, in most physical systems, interactions with the surrounding

environment rapidly disrupt these superposition states. A typical disruption would effectively

change a superposition of 0 and 1 randomly into either a 0 or a 1, as process called decoherence.

State-of-the-art qubits based on the charge of electrons in a semiconductor remain coherent for a

few picoseconds at best and only at temperatures too low for practical applications. The rapid

decoherence occurs because the electric force between charges is strong and long range.

In traditional semiconductor devices, this strong interaction is beneficial, permitting delicate

control of current flow with small electronic fields. To quantum coherent devices, however, it is

disadvantage.

As a result, an experiment was conducted on the qubits, which are based on the electron-spin.

Electron-spin qubits interact only weakly with the environment surrounding them, principally

through magnetic fields that are non-uniform in space or changing in time. Such fields can be

effectively shielded. The goal of the experiment was to create some of these coherent spin states

in a semiconductor to see how long they could survive. Much to the surprise, the optically

excited spin states in ZnSe remained coherent for several nanoseconds at low temperatures—

1,000 times as long as charge-based qubits. The states even survived for a few nanoseconds at

room temperature. Subsequent studies of electrons in gallium arsenide (GaAs) have shown that,

under optimal conditions, spin coherence in a semiconductor is possible.

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Spintronic Qubits

1. In a conventional computer every bit has a definite value of 0 or 1. A series of eight bits

can represent any number from 0 to 255, but only one number at a time.

2. Electron spins restricted to spin up and spin down could be used as bits.

3. Quantum bits, or qubits, can also exist as super positions of 0 and 1, in effect being both

numbers at once. Eight qubits can represent every number from 0 to 255 simultaneously.

4. Electron spins are natural qubits; tilted electrons is a coherent superposition of spin up

and spin down and is less fragile than other quantum electronic states.

5. Qubits are extremely delicate: stray interactions with their surroundings degrade the

superposition extremely quickly, typically converting them in to random ordinary bits.

While a classical three-bit state and a quantum three-qubit state are both eight-

dimensional vectors, they are manipulated quite differently for classical or quantum

computation. For computing in either case, the system must be initialized, for example into the

all-zeros string, corresponding to the vector (1, 0, 0,0,0,0, 0, and 0). In classical

randomized computation, the system evolves according to the application of stochastic matrices,

which preserve that the probabilities add up to one (i.e., preserve the L1 norm). In quantum

computation, on the other hand, allowed operations are unitary matrices, which are effectively

rotations (they preserve that the sums of the squares add up to one, the Euclidean or L2 norm).

(Exactly what unitaries can be applied depend on the physics of the quantum device.)

Consequently, since rotations can be undone by rotating backward, quantum computations

are reversible. (Technically, quantum operations can be probabilistic combinations of unitaries,

so quantum computation really does generalize classical computation. See quantum circuit for a

more precise formulation.)

Finally, upon termination of the algorithm, the result needs to be read off. In the case of a

classical computer, we sample from the probability distribution on the three-bit register to obtain

one definite three-bit string, say 000. Quantum mechanically, we measure the three-qubit state,

which is equivalent to collapsing the quantum state down to a classical distribution (with the

coefficients in the classical state being the squared magnitudes of the coefficients for the

quantum state, as described above) followed by sampling from that distribution. Note that this

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destroys the original quantum state. Many algorithms will only give the correct answer with a

certain probability; however by repeatedly initializing, running and measuring the quantum

computer, the probability of getting the correct answer can be increased.

4.4 Spintronic Scanner

Cancer cells are the somatic cells which are grown into abnormal size. The Cancer

cells have different electromagnetic sample when compared to normal cells. For many types

of Cancer, it is easier to treat and cure the Cancer if it is found early. There are many different

types of Cancer, but most Cancers begin with abnormal cells growing out of control, forming a

lump that's called a tumor. The tumor can continue to grow until the Cancer begins to spread to

other parts of the body. If the tumor is found when it is still very small, curing the Cancer can be

easy. However, the longer the tumor goes unnoticed, the greater the chance that the Cancer has

spread. This makes treatment more difficult. Tumor developed in human body, is removed by

performing a surgery. Even if a single cell is present after the surgery, it would again develop

into a tumor. In order to prevent this, an efficient route for detecting the Cancer cells is

required. Here, in this paper, we introduce a new route for detecting the Cancer cells after a

surgery. This accurate detection of the existence of Cancer cells at the beginning stage itself

entertains the prevention of further development of the tumor.

This spintronic scanning technique is an efficient technique to detect cancer cells even when they

are less in number.

An innovative approach to detect the cancer cells with the help of Spintronics:

The following setup is used for the detection of cancer cells in a human body:

(a)Polarized electron source

(b) Spin detector

(c)Magnetic Field

4.4.1Polarized electron source:

A beam of electrons is said to be polarized if their spins point, on average, in a specific direction.

There are several ways to employ spin on electrons and to control them. The requirement for this

paper is an electron beam with all its electrons polarized in a specific direction. The following

are the ways to meet the above said requirement: Photoemission from negative electron affinity

GaAs Chemi-ionization of optically pumped meta stable Helium An optically

pumped electron spin filter A Wein style injector in the electron source A spin filter is more

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efficient electron polarizer which uses an ordinary electron source along with a gaseous layer of

Rb. Free electrons diffuse under the action of an electric field through Rb vapour that has been

spin polarized in optical pumping. Through spin exchange collisions with the Rb, the free

electrons become polarized and are extracted to form a beam. To reduce the emission of

depolarizing radiation, N2 is used to quench the excited Rb atoms during the optical pumping

cycle.

4.4.2 Spin detectors:

There are many ways by which the spin of the electrons can be detected efficiently. The spin

polarization of the electron beam can be analyzed by using:

(a)Mott polarimeter

(b)Compton polarimeter

(c)Moller type polarimeter

Typical Mott polarimeters require electron energies of ~100 kV. But Mini Mott polarimeter uses

energies of ~25 keV, requiring a smaller overall design. The Mini Mott polarimeter

has three major sections: the electron transport system, the target chamber, and the detectors. The

first section the electrons enter is the transport system. An Einsel lens configuration was used

here. Two sets of four deflectors were used as the first and last lens. The electrons next enter the

target chamber. The chamber consists of a cylindrical target within a polished stainless steel

hemisphere. A common material used for the high-Z nuclei target is gold. Low-Z nuclei help

minimize unwanted scattering, so aluminum was chosen. Scattered electrons then exit the target

chamber and are collected in the detectors. Thus there are many methods for detecting the spin

polarization of electrons.

4.4.3 External Magnetic Field:

An external magnetic field is required during this experiment. The magnetic field is applied after

the surgery has undergone. First, it is applied to an unaffected part of the body and then to the

surgery undergone part of the body. It is already mentioned that the magnetic field could easily

alter the polarization of electrons.

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This technique using spintronics is suggested by us to identify tumor cells after surgery.

The procedure for doing this experiment is as follows:

Optical Spin Filter:

After surgery and the removal of the tumor, the patient is exposed to a strong magnetic field.

Now the polarized electron beam is applied over the unaffected part and spin orientation of

electrons are determined using polarimeter. Then the same polarized beam is targeted over the

affected part of the body and from the reflected beam, change in spin is determined. Based on

these two values of spin orientation, the presence of tumor cells can be detected even if they are

very few in number. Hence, we suggest this method for the detection purpose. A detailed view of

this innovative approach is given as follows.

Spin Orientation of the unaffected part of the body:

Applying Magnetic Field:

When the magnetic field is applied to the unaffected part of the human body, the normal somatic

cells absorbs the magnetic energy and retains it.

Determinig the Spin orientation:

When the electrons get incident on the cells the magnetic energy absorbed by the cells alters the

spin orientation of the electrons. These electrons get reflected and it is detected by the Mott

polarimeter. Then the change in spin orientation of the electrons is measured as Sx.

Spin Orientation of the surgery undergone part of the body:

Applying Magnetic Filter:

In the surgery undergone part of the body an external magnetic field is applied. The cancer cells

which are present, if any, will absorb more magnetic energy than the normal cells since they

differ in their electromagnetic pattern.

Determinig the spin Orientation:

Now an electron beam which is polarized is incident on the surgery undergone part of the body.

The magnetic energy absorbed by the cancer cell alter the spin orientation of the electron beam.

Since cancer cells absorb more magnetic energy, the change in orientation caused by them is also

more. If no cancer cells are present the amount of change is equal to the previous case. The

change in spin is measured by the polarimeter as Sy.

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Inference:

If the change in the spin in the unaffected part of the body is same as that of the surgery

undergone part, i.e.

If Sx=Sy

Then,

There are no cancer cells in the surgery undergone part of the body and all the cells have

been removed by the surgery.

If the change in spin in the unaffected part is not equal to the change caused by the surgery

undergone part of the body, i.e.

If Sx not equals Sy

Then,

There are some cancer cells in the surgery undergone part of the body and the cancer cells are

not completely removed by the surgery.

The steps involved are:

1) The patient is exposed to a strong magnetic field so that his body cell gets magnetized.

2) A beam of electrons with polarized spin is introduced on the unaffected part of the body and

the change in spin is detected by a polarimeter. Let it be X

3) A beam of electrons with polarized spin is introduced on the part which had undergone

surgery. And the corresponding change in spin be Y

4)If X - Y = 0, it indicates that cancer cells have been removed from the body, if not it indicates

the presence of traces of cancer cells and it has to be treated again for ensuring complete safety

to the patient

Thus this technique efficiently identifies the presence of cancer cells in that part of the body that

has undergone surgery to prevent any further development.

5. Conclusion:

So with this paper we have proved that the new generation of computing and information

technology is on its way to revolutionize the 21st century. We believe it makes sense instead to

build on the extensive foundations of conventional electronic semiconductor technology; we

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exploit the spin of the electron and create new devices and circuits, which could be more

beneficial. Spintronics, which depend on the spin of the electron, has a great potential of

spinning this global village into an unexpected digital atomic world which has a capability of

manipulating at atomic level. This would make things smaller and cheaper and more affordable

by a common man. What ever may be the discovery or invention made will have its worth

forever only if it finds its use in common man’s life. We wish and hope spintroincs will have it’s

into common man’s life.

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