中国科学院物理研究所 通用 实验技术公共课程
description
Transcript of 中国科学院物理研究所 通用 实验技术公共课程
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主 要 内 容
• 提拉样品磁强计的原理和型式 步进提拉方式( MPMS ) 匀速提拉方式( ESM 、 ACM
S ) 往复提拉方式( RSO )• MPMS 的主要功能及其使用 温度、磁场的控制 磁矩的检测、功能 样品、维护、注意事项
物理所磁学室公共测试讲座
共 135 页
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ESM 的基础 -1 ESM1
抛移线圈:冲击法(课程六)
0 ,0 , , S Nt B H T t C
CS, N :线圈磁通常数
迴线仪
0 0 00( , , ) ( , , )S S
r r rtB m d S B m d St
tt t
t t
������������������������������������������ ���������������������������� �������������� ����������������������������
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ESM 的基础 -2 ESM2
点磁偶极子( point dipole )假设 ?
0 0( )r t x x i y kty j z
n
x
y
z
O
(x0, y0, z)
(x, y, 0)
检测线圈
m��������������
( )r t
rc
0
5 3
3( , , )
4
m r r mB m r t
r r
������������������������������������������ ��������������������������������������������������������
检测线圈内的磁通量:
( , , )S
t B m r t d S ��������������������������������������������������������
检测线圈内的磁场强度:
5
9
与 VSM 相同的处理方法 ESM3
样品位于检测线圈的轴线上
2
20
0 32
, ,2
c
c
z rt
mz
zm
tr
单匝检测线圈内的磁通量:
单匝检测线圈内的感应电势:
0
0
20
5
2
22
, , 3( , , )
2c
c
zm mt r
tz z t z t
ztz tt r
m
平行于轴向的 VSM
10
与 VSM 相同的处理方法 ESM4
样品偏离轴线 距离单匝检测线圈内的磁通量: n = 2
2
2 0 22
2
2
3 2,
2, , , , 1
4
cc c
c
rr rt t
r
z tz z
z t
zm
tm
单匝检测线圈内的感应电势: n = 2
2 2
2
2
2 02 22
5, , , , , 1
4
3 4
c
cc r z tz z
z t
rtm m t
r
平行于轴向的 VSM
11
与 VSM 相同的处理方法 ESM5
一级梯度线圈(串联反接的两个相同线圈)
, , , , , , ,i
i
SS
z zN mtm t
一级梯度线圈
+
_1
_ 2
, ,2
,
,2
,
, , ,
Coil
Coil
t t N
t N
z
m z
m
平行于轴向的 VSM
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与 VSM 相同的处理方法 ESM6
二级梯度线圈(串联的两组一级梯度线圈)
, , , , , , ,i
i
SS
z zN mtm t
_ _1&2
_
_
, , , ,
, , , ,
, , , ,
2 Coil center
Coil top
Coil bottom
t t Nm z
t
m
z Nm
tz N
平行于轴向的 VSM
二级梯度线圈 (MPMS)
+
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ESM 仪器设备 ESM6
ESM 的原理:积分式磁强计
t
ε
0 t0 2t0
+ -
dt
dt
)(
1. 提拉速率:高2. 使用积分器3. 磁矩定标: Ni
4. 灵敏度低于 VSM
5. 开路测量
1. 提拉速率:高2. 使用积分器3. 磁矩定标: Ni
4. 灵敏度低于 VSM
5. 开路测量
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ESM 仪器设备 ESM7
ESM 的构成
1. 均匀磁场:2. 样品提拉系统:3. 信号采集系统:4. 测量控制系统
SS
SdZtTHBSdZtTHB
),,,(),,,( 11112222
0( , , , ) ( , ) ( , , , )B H T t Z H t Z M H T t Z 其中,
0 ( )( , , , ) ( , ) ZB H T t Z H M H T
( ) 1Z ( ) 0Z
dtK
THM
THMKt
02
1),(
),(2
清零
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ESM 仪器设备 ESM8
ESM :磁矩的检测
0( , , , ) ( , ) ( , , , )B H T t Z H t Z M H T t Z Z
0( , , , ) ( , )B H T t Z H M H T ( ) 1Z
( ) 0Z HZtTHB ),,,(
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提 拉 样 品 磁 强 计 ESM9
ESM 的现状
1. 单点测量时间短、灵敏度略低;2. PPMS_ACMS 的直流磁性测量采用提拉法;3. MPMS 、 MPMS XL 的直流磁性测量;4. 磁学室原有一台 ESM ( CF-1 型);5. 现在已经很少有独立的 ESM 。
1. 单点测量时间短、灵敏度略低;2. PPMS_ACMS 的直流磁性测量采用提拉法;3. MPMS 、 MPMS XL 的直流磁性测量;4. 磁学室原有一台 ESM ( CF-1 型);5. 现在已经很少有独立的 ESM 。
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MPMS 的原理 MPMS1
QD_MPMS ( XL )
By Mike McElfresh
Fundamentals of Magnetism and Magnetic Measurements
Featuring Quantum Design’s Magnetic Property Measurement System
http://www.qdusa.com/sitedocs/appNotes/mpms/FundPrimer.pdf
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名词:超导量子磁强计 中华人民共和国计量技术规范 JJG 1013 -89
《磁学计量常用名词术语及定义(试行)》
4.95 超导量子磁强计: Superconducting Quantum magnetometer
中华人民共和国计量技术规范 JJG 1013 -89
《磁学计量常用名词术语及定义(试行)》
4.95 超导量子磁强计: Superconducting Quantum magnetometer
中文:超导量子磁强计; SQUID 磁强计
英文: SQUID Magnetometer ; SQUID (Superconducting Quantum
Interference Device) Magnetometer20
The ChronologyThe Chronology
1911 – Heike Kammerlingh Onnes discovers superconductivity1911 – Heike Kammerlingh Onnes discovers superconductivity• 1913 Receives the Nobel Prize in Physics1913 Receives the Nobel Prize in Physics
1962 – Brian Josephson predicts the “Josephson Effect”1962 – Brian Josephson predicts the “Josephson Effect”• 1973 Receives the Nobel Prize in Physics1973 Receives the Nobel Prize in Physics
1986 – Bednorz and Muller discover High Temperature 1986 – Bednorz and Muller discover High Temperature SuperconductivitySuperconductivity• 1987 They receive the Nobel Prize in Physics1987 They receive the Nobel Prize in Physics
After Bill of QD, 2006
The SQUIDThe SQUID
Within a year of Brian Josephson’s discovery, the first Within a year of Brian Josephson’s discovery, the first Superconducting Quantum Interference Device (SQUID) was builtSuperconducting Quantum Interference Device (SQUID) was built
In 1968, Professor John Wheatley of In 1968, Professor John Wheatley of UCSDUCSD and four other and four other international physicists founded S. H. E. Corp. (Superconducting international physicists founded S. H. E. Corp. (Superconducting Helium Electronics) to commercialize this new technology.Helium Electronics) to commercialize this new technology.
After Bill of QD, 2006
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SQUID MagnetometersSQUID Magnetometers The first SQUID magnetometer was developed by The first SQUID magnetometer was developed by Mike SimmondsMike Simmonds, ,
Ph.D. and Ph.D. and Ron SagerRon Sager, Ph.D. while at S.H.E. Corporation in 1976., Ph.D. while at S.H.E. Corporation in 1976. In 1982, Mike and Ron, along with two other SHE employees, founded In 1982, Mike and Ron, along with two other SHE employees, founded
Quantum Design.Quantum Design. In 1984, QD began to market the next generation SQUID magnetometer – the In 1984, QD began to market the next generation SQUID magnetometer – the
Magnetic Property Measurement System (MPMS).Magnetic Property Measurement System (MPMS). In 1996, QD introduced the MPMS XL as the latest generation SQUID In 1996, QD introduced the MPMS XL as the latest generation SQUID
magnetometermagnetometer During the past 22 years, six companies have unsuccessfully designed and During the past 22 years, six companies have unsuccessfully designed and
marketed SQUID magnetometers to compete with the MPMS. marketed SQUID magnetometers to compete with the MPMS. 26
After Bill of QD, 2006
MPMS XL Temperature ControlMPMS XL Temperature Control Patented dual impedance design allows continuous operation below Patented dual impedance design allows continuous operation below
4.2 K4.2 K Sample tube thermometry improves temperature accuracy and controlSample tube thermometry improves temperature accuracy and control Transition through 4.2 K requires no He reservoir refilling and Transition through 4.2 K requires no He reservoir refilling and
recycling (no pot fills)recycling (no pot fills) Temperature sweep mode allows measurements while sweeping Temperature sweep mode allows measurements while sweeping
temperature at user controlled ratetemperature at user controlled rate• Increases measurement speedIncreases measurement speed
Smooth temperature transitions through 4.2 K both cooling and Smooth temperature transitions through 4.2 K both cooling and warmingwarming
After Bill of QD, 2006
MPMS XL Temperature ControlMPMS XL Temperature Control
After Bill of QD, 2006
MPMS 、 SQUID_VSM :独立的温度、气氛环境
MPMS XL Temperature ControlMPMS XL Temperature Control
我的评价
Set Temperature 10 KWait for temperature stable 30 min
70 min
MPMS XL Temperature ControlMPMS XL Temperature Control
我的评价
OverShoot!
Stabilizing!
JIm (QD):
The idea is just to wait some extra time for upper section
(stainless steel slow to change) of sample tube to cool do
wn and get lower thermal gradient. Otherwise, the extra he
at load will prevent stabilizing and/or holding 2 K.
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程序设定:
在 10 K 快速稳定的小技巧• 重复设定温度 10
K
手动:
Set Temperature 10 K
Set Temperature 10.000K at 10.000K/min.Waitfor Delay:1800secsSet Temperature 10.000K at 10.000K/min.Waitfor Delay:300secsSet Temperature 10.000K at 10.000K/min.Waitfor Delay:300secsSet Temperature 10.000K at 10.000K/min.Waitfor Delay:300secs
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Wait for
• Wait for
• Wait for Temp Stable
• Wait for Temperature
• Wait for Field
• Wait for Position
MPMS XL Temperature ControlMPMS XL Temperature Control
Temperature Range: Temperature Range: 1.9 - 400 K (800 K with optional oven)1.9 - 400 K (800 K with optional oven) Operation Below 4.2 K: Operation Below 4.2 K: ContinuousContinuous Temperature Stability: Temperature Stability: ±0.5% ±0.5% Sweep Rate Range: Sweep Rate Range: 0.01 - 10 K/min with smooth transitions 0.01 - 10 K/min with smooth transitions
through 4.2 Kthrough 4.2 K Temperature Calibration Temperature Calibration ±0.5% typical ±0.5% typical
Accuracy: Accuracy: Number of Thermometers: Number of Thermometers: 2 (one at bottom of sample tube; one at 2 (one at bottom of sample tube; one at
the the location of sample measurements)location of sample measurements)
After Bill of QD, 2006
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41
T1+
-
时间
温度
控温模式:单点设定温度设定温度 : T 1 KelvinSet Temperature to : T 1 Kelvin
升 温测 量
显示QUENSQ
20 秒 40 秒
如果温度在 T1内系统认为温度稳定
显示温度
实际温度
MPMS3
Tolerence
= 0.005 T 1
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控温模式:扫描温度
扫描温度到 : T S Kelvin
Set Temperature to : T 1 Kelvin
Sweep Rate : 1 mK/min~ 10 K/min
Sweep Temperature to : T S Kelvin
扫描到 某一温度
设定 起始温度
设定 变温速率
扫描到 某一温度
MPMS5
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时间
温度
控温模式:扫描温度
同时进行升 温、降 温 测 量
T S
T F
T = (T S + T F)/2
测量过程中温度变化测量
开始 /结束
测量结束 / 开始
MPMS6
Sweep Temperature 40
Very high homogeneity magnets (1, 5 and 7 Tesla)• 0.01% uniformity over 4 cm
Magnets can be operated in persistent or driven mode • Hysteresis mode allows faster hysteresis loop measurements
Magnets have two operating resolutions: standard and high resolution
Magnetic Field ControlMagnetic Field Control
Type of Magnet Standard resolution High resolution1 tesla 0.5 Oe 1.0 tesla 0.05 Oe 1500 Oe5 tesla 1 Oe 5.0 tesla 0.1 Oe 5000 Oe7 tesla 2 Oe 7.0 tesla 0.2 Oe 6000 Oe
After Bill of QD, 2006
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SQUID 磁强计 磁场控制示意图MPMS7
可调电阻
电源
R
E
K
I
I2 I1
超 导 开 关开 关 电 阻 r
闭环: r = 0 ; I2 = -I1
开环: r = rn ; I2 = 0
超导磁体液 氦
闭环运行开环运行 不加热
电源开关
加热
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磁场变化的模式开环模式: Hysteresis Mode
开关电阻为正常态; 电源与超导磁体线圈保持接通; 实际磁场与设定值相差一小量。
闭环模式: No Overshoot Mode
闭环模式: Oscillate Mode
H
MPMS9 - 1
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关于变场速率• 电感-电源电压
coilsource
souri
cl
eco
d
dt
di
tL
d
Lcoil : 20 H ~ 35 H
source : 2.0 V ~ 5.0 V
A/ssourc
coil
urce eso
L
di
dt
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关于变场速率• 电感-电源电压
磁体线圈电感( H ) 20 ~ 35
磁体电源电压( V ) 2.0 ~ 5.0
电流变化最高速率( A/s ) 0.057 ~ 0.25
磁场变化最高速率( Oe/s )
/ ( ) [T/A]B
B I atioI
r
磁场 /电流比:(线圈几何灵敏因子)
2062.71 Oe/A
117 Oe/s ~ 515 Oe/s
MPMS10
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互易性原理 VSM7
均匀磁化( homogeneous magnetization )
rc
z(t)
coilg
dr td tt
dtm
dtr
I
m
coil
B rg r
I
coil
B rk r
I定义:
coil
k rg
k r k r
x yr
z
圆形电流线圈的磁场(春)
gcoil :几何(位置)灵敏因子
小样品!
课程三
Reciprocating Sample Measurement SystemReciprocating Sample Measurement System(RSO)(RSO)
After Bill of QD, 2006
Reciprocating Sample Measurement SystemReciprocating Sample Measurement System(RSO)(RSO)
Frequency Range:Frequency Range: 0.5 - 4 Hz0.5 - 4 Hz Oscillation Amplitude:Oscillation Amplitude: 0.5 - 50 mm0.5 - 50 mm Relative Sensitivity:Relative Sensitivity: 1 x 101 x 10-8-8 emu emu; H ; H 2,500 Oe, T = 100 2,500 Oe, T = 100
K K (for 7-tesla magnet)(for 7-tesla magnet)
6 x 106 x 10-7-7 emu; H @ 7 tesla, T = 100 K emu; H @ 7 tesla, T = 100 K (for (for 7-tesla magnet)7-tesla magnet)
Dynamic rangeDynamic range 1010-8-8 to 5 emu (300 emu with Extended to 5 emu (300 emu with Extended Dynamic Range option)Dynamic Range option)
After Bill of QD, 2006
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MPMS RSO 的原理 MPMS RSO 1
原理上的可行性
2
20
0 32
, ,2
c
c
z rt
mz
zm
tr
0
0
20
5
2
22
, , 3( , , )
2c
c
zm mt r
tz z t z t
ztz tt r
m
单匝检测线圈内的磁通量:
单匝检测线圈内的感应电势:
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MPMS RSO 的原理 MPMS RSO 2
原理上的可行性
20
0 32
2
32
2
2
2
2 32
2, ,
2c
c
c
c
c
c
z rt
r
r
r
r
r
zz t
z t
z
m
t
m
二级梯度线圈内的磁通量:
二级梯度线圈
+
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MPMS RSO 的原理 MPMS RSO 3
原理上的可行性
max max
2max m
2 22 2 2 2max
7/ 2 7/ 2 7 / 22 2 22ax max
2
2 4 4 40
c c c
c c c
z r r rz z
z z zr r r
二级梯度线圈内的磁通量对位置的导数:
max ,cf rz
只与线圈的尺寸和相对位置有关,是确定的。
?
MPMS XL : 0.62 cm ( QD )、 0.587 cm (计算)
rc= 0.97 cm= 1.519 cm
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MPMS RSO 的使用 MPMS RSO 4
1 、硬件:使用伺服马达驱动 专用 RSO 传输台( RSO motor )
2 、功能:实现 MPMS 的快速测量 磁矩~磁场、温度关系
3 、适用性:磁矩上限: 0.5 emu ? 仅适用于所有的磁性测量
JIm:
Yes, EDR is automatically enabled with RSO, whenever over-
range error reported at normal maximum 1.25 emu scale.
MPMS System OptionsMPMS System Options
Transverse Moment DetectionTransverse Moment Detection• for examining anisotropic effectsfor examining anisotropic effects
• Second SQUID detection systemSecond SQUID detection system SQUID AC SusceptibilitySQUID AC Susceptibility
• 2 x 102 x 10-8-8 emu sensitivity 0.1 Hz to 1 emu sensitivity 0.1 Hz to 1 kHzkHz
Ultra-Low FieldUltra-Low Field• Reduce remanent magnet field to Reduce remanent magnet field to ±±0.0.
05 Oe05 Oe Extended Dynamic RangeExtended Dynamic Range
• Measure moments to ±300 emuMeasure moments to ±300 emu External Device ControlExternal Device Control
• Control user instruments with the MControl user instruments with the MPMSPMS
10 kBar Pressure Cell10 kBar Pressure Cell
Sample RotatorsSample Rotators• Vertical and HorizontalVertical and Horizontal
Sample Space OvenSample Space Oven• Temperatures to 800 KTemperatures to 800 K
Environmental Magnetic ShieldsEnvironmental Magnetic Shields Fiber Optic Sample HolderFiber Optic Sample Holder
• Allows sample excitation with lightAllows sample excitation with light Manual Insertion Utility ProbeManual Insertion Utility Probe
• Perform elector-transport Perform elector-transport measurements in MPMSmeasurements in MPMS
Liquid Nitrogen Shielded DewarLiquid Nitrogen Shielded Dewar EverCool Cryocooled DewarEverCool Cryocooled Dewar
• No-Loss liquid helium dewarNo-Loss liquid helium dewar
• No helium transfersNo helium transfers
After Bill of QD, 2006
13+1
Transverse Moment DetectionTransverse Moment Detection
Measures anisotropic effects of Measures anisotropic effects of moments with vector moments with vector components perpendicular to components perpendicular to the applied fieldthe applied field
Incorporates a second SQUID Incorporates a second SQUID detection system which can detection system which can resolve transverse moments as resolve transverse moments as small as 10small as 10-6-6 emu emu
Second-order detection coils Second-order detection coils orthogonal to the longitudinal orthogonal to the longitudinal detection coilsdetection coils
After Bill of QD, 2006
SQUID AC SusceptibilitySQUID AC Susceptibility Dynamic measurement of sampleDynamic measurement of sample
• Looks also at the resistance and conductanceLooks also at the resistance and conductance
• Can be more sensitive the DC measurementCan be more sensitive the DC measurement Measures Real (Measures Real () and Imaginary () and Imaginary () components) components
is the resistance of the sampleis the resistance of the sample is the conductive partis the conductive part
Proportional to the energy dissipation in the sampleProportional to the energy dissipation in the sample
Must resolve components of sample moment that is out of phase with Must resolve components of sample moment that is out of phase with the applied AC fieldthe applied AC field• SQUID is the best for this because it offers a signal response that is SQUID is the best for this because it offers a signal response that is
virtually flat from 0.01 Hz to 1 kHzvirtually flat from 0.01 Hz to 1 kHz Available on all MPMS XL systemsAvailable on all MPMS XL systems Requires system to be returned to factory for upgradeRequires system to be returned to factory for upgrade
After Bill of QD, 2006
SQUID AC SusceptibilitySQUID AC Susceptibility FeaturesFeatures
• Programmable Waveform Synthesizer and high-speed Analog-to-Digital Programmable Waveform Synthesizer and high-speed Analog-to-Digital converterconverter
• AC susceptibility measured automatically and can be done in combination AC susceptibility measured automatically and can be done in combination with the DC measurementwith the DC measurement
• Determination of both real and imaginary components of the sample’s Determination of both real and imaginary components of the sample’s susceptibilitysusceptibility
• Frequency independent sensitivityFrequency independent sensitivity SpecificationsSpecifications
• Sensitivity (0.1 Hz to 1 kHz):Sensitivity (0.1 Hz to 1 kHz): 2 x 102 x 10-8-8 emu @ 0 Tesla emu @ 0 Tesla
1 x 101 x 10-7-7 emu @ 7 emu @ 7 TeslaTesla
• AC Frequency Range:AC Frequency Range: 0.01 Hz to 1 kHz0.01 Hz to 1 kHz• AC Field Range:AC Field Range: 0.0001 to 3 Oe (system dependent)0.0001 to 3 Oe (system dependent)• DC Applied Field:DC Applied Field: ±±0.1 to 70 kOe (system dependent)0.1 to 70 kOe (system dependent)
After Bill of QD, 2006
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Ultra-Low Field CapabilityUltra-Low Field Capability
Actively cancels remanent field in all MPMS superconducting Actively cancels remanent field in all MPMS superconducting magnetsmagnets
Sample space fields as low as Sample space fields as low as ±±0.1 Oe achievable0.1 Oe achievable Custom-designed fluxgate magnetometer suppliedCustom-designed fluxgate magnetometer supplied Includes Magnet ResetIncludes Magnet Reset Requires the Environmental Magnet ShieldRequires the Environmental Magnet Shield
After Bill of QD, 2006
Extended Dynamic RangeExtended Dynamic Range
Extends the maximum measurable moment from ± 5 emu to ± 300 emu Extends the maximum measurable moment from ± 5 emu to ± 300 emu (10 orders of magnitude)(10 orders of magnitude)
Automatically selected when needed in measurementAutomatically selected when needed in measurement Effective on both longitudinal and transverse SQUID systems Effective on both longitudinal and transverse SQUID systems
After Bill of QD, 2006
75
关于 MPMS 的量程( 1 )• 基本量程( Primary Dynamic Rang
e )DC Transport :
1.25 emu
4 cm, 32-point scan
10.0 emu
4 cm, 64-point scan
> 10.0 emu ?
Holding: 64 points per scan RSO :0.4 emu
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关于 MPMS 的量程( 3 )• 扩展量程( Extended Dynamic Rang
e )DC Transport :RSO :
300 emu
4 cm, 64-point scan
JIm :EDR basically just puts a transformer between pick-up coil and SQUID capsule to reduce current generated in gradiometer by very large signals. While we of course calibrate the impact from extra electronic components, there will always be a distinct step in the data at this transition.
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超导量子干涉器件的应用磁通的间接测量:电流负反馈
SQUID13
间接使用
x
Lp , NpLs , Ns
i , LLead
M
L
p
p s leadfx fM
L LM
N
Li
ifrf
Output
SQUID检测电路
B = 0
Mf
课程二
Sample Space OvenSample Space Oven Provides high temperature measurement capabilityProvides high temperature measurement capability
• Ambient to Ambient to 800 K800 K Easily installed and removed by the user when neededEasily installed and removed by the user when needed A minimal increase in helium usageA minimal increase in helium usage
• Approximately 0.1 liters liquid helium/hourApproximately 0.1 liters liquid helium/hour 3.5 mm diameter sample space3.5 mm diameter sample space
After Bill of QDAfter Bill of QD, 2006
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MPMS Horizontal RotatorMPMS Horizontal Rotator
Automatically rotates sample about a horizontal axis during magnetic Automatically rotates sample about a horizontal axis during magnetic measurementmeasurement
360 degrees of rotation; 0.1 degree steps360 degrees of rotation; 0.1 degree steps Sample platform is 1.6 X 5.8 Sample platform is 1.6 X 5.8 Diamagnetic background signal of 10Diamagnetic background signal of 10-3-3 emu at 5 tesla emu at 5 tesla
(课程一):样品总磁矩 < 0.1 memu
After Bill of QD, 2006
Manual Insertion Utility ProbeManual Insertion Utility Probe
Perform electro-transport measurement in the MPMS sample spacePerform electro-transport measurement in the MPMS sample space 10-pin connector10-pin connector Use with External Device Control (EDC) for controlling external devices (e.g., Use with External Device Control (EDC) for controlling external devices (e.g.,
voltmeter and current source)voltmeter and current source)• Creates fully automated electro-transport measurement systemCreates fully automated electro-transport measurement system
After Bill of QD, 2006
http://www.http://www.qd-chinaqd-china.com/upfile/news/201071245437533.pdf.com/upfile/news/201071245437533.pdf
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External Device ControlExternal Device Control
Allows control and data read back from third party electronicsAllows control and data read back from third party electronics Allows custom control of MPMS electronicsAllows custom control of MPMS electronics Use with Manual Insertion Utility Probe for automated electro-Use with Manual Insertion Utility Probe for automated electro-
transport measurementstransport measurements MPMS MultiVu version written in MPMS MultiVu version written in Borland’s DelphiBorland’s Delphi (Visual Pascal) (Visual Pascal)
programming languageprogramming language
After Bill of QD, 2006
Hysteresis MeasurementHysteresis Measurementmade with External Device Control (EDC)made with External Device Control (EDC)
Using EDCUsing EDC to control a DC field using the AC coil in the MPMS to control a DC field using the AC coil in the MPMS
Up to ± 8 Oe DC field (system dependent)Up to ± 8 Oe DC field (system dependent) Step size as small as 1.9 Step size as small as 1.9 OeOe
20 Å Ni Thin Film (PSI, Zurich)
After Bill of QD, 2006
Fiber Optic Sample HolderFiber Optic Sample Holder
Allows sample to be illuminated by an external light source while making Allows sample to be illuminated by an external light source while making magnetic measurementsmagnetic measurements
Optimized for near UV spectrum (180 to 700 nm)Optimized for near UV spectrum (180 to 700 nm) Includes 2-meter fiber optic bundleIncludes 2-meter fiber optic bundle Sample bucket 1.6 mm diameter and 1.6 mm deepSample bucket 1.6 mm diameter and 1.6 mm deep
Slide seal
Fiber optic bundle
SMA connector
After Bill of QD, 2006
Firberguide Industries: Superguide G UV-Vis fiber
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只与磁性测量兼容只与磁性测量兼容
MPMS Liquid Helium Dewar OptionsMPMS Liquid Helium Dewar Options
Basic system supplied with a vapor shielded 56 liter dewarBasic system supplied with a vapor shielded 56 liter dewar Liquid nitrogen jacketed version of the basic dewar improves hold Liquid nitrogen jacketed version of the basic dewar improves hold
time by ~ 30%time by ~ 30% MPMS EverCool Cryocooled DewarMPMS EverCool Cryocooled Dewar
After Bill of QD, 2006
85
MPMS EverCool DewarMPMS EverCool Dewar
Designed to eliminate the need for liquid helium transfersDesigned to eliminate the need for liquid helium transfers Virtually eliminates all helium loss from the Quantum Design MPMS Virtually eliminates all helium loss from the Quantum Design MPMS
magnetometer systemmagnetometer system Cryocooler-dewar system that recondenses the helium directly in the Cryocooler-dewar system that recondenses the helium directly in the
dewardewar Integrated into MPMS Operating SystemIntegrated into MPMS Operating System Cryocooler operation can be controlled automatically to minimize Cryocooler operation can be controlled automatically to minimize
interference with sensitive magnetic measurementsinterference with sensitive magnetic measurements Available as an upgrade to all MPMS systems (Available as an upgrade to all MPMS systems (nono equipment needs to equipment needs to
be returned to Quantum Design)be returned to Quantum Design) Available with water or air cooled compressorAvailable with water or air cooled compressor
After Bill of QD, 2006
MPMS EverCool DewarMPMS EverCool Dewar
CryocoolerCryocoolercoldheadcoldhead
Liquid heliumLiquid heliumcondenser unitcondenser unit
After Bill of QD, 2006
非常感谢物理所建立了低温条件保障中心!向在低温车间辛勤劳动的全体人员致敬!
New Product: New Product: High Pressure CellHigh Pressure Cell
Manufactured by easyLab Manufactured by easyLab Limited in the UKLimited in the UK
Offers 10 kbar of pressureOffers 10 kbar of pressure Supplied with complete Supplied with complete
user’s kituser’s kit
M06组
After Bill of QD, 2006
New Product: New Product: 33Helium SystemHelium System
Minimum temperature of 0.48KMinimum temperature of 0.48K Manufactured and marketed by Manufactured and marketed by
IQUANTUM of JapanIQUANTUM of Japan
After Bill of QD, 2006
90
97
超导量子磁强计的运行(条件)
1 、使用液氦 总容量: 56 升; 初次冷却: 100 升; 液氦的自然蒸发: 3 升 ~ 5 升 / 天( 5 K 时) 30 % 以下:必须输入液氦; 50 % 以上: 5 T 磁
场
2 、电力要求 交流( 2205 % ) V
3 、环境要求 温度( < 30 C )、湿度( < 80 % )
超导量子磁强计的操作MPMS操作 3
98
样品的安装(原则与方法) 探测线圈的设计原理 超导量子磁强计的磁矩探测线圈采用 Second-order Gradiometer
几何构形。最主要特点是:当一个均匀的长样品在探测线圈中 移动时,只要样品的长度远远大于探测线圈的长度,则该样品 在探测线圈中不会产生信号。
样品架的选择 石英管、吸管 厚度均匀、质量轻、密度低、磁化率小、热稳定性高
安装样品的方法(推荐) 样品尺寸缩小、样品径向居中、内外压力平衡、样品刚性安放
超导量子磁强计的操作样品安装 1
108
关于弱磁性信号的样品• 背景、背景的扣除
自动扣除背景: 能用!
信号:~ 100 背景:~ 10
100 10 10100% 0.909
100 10
信号:~ 1.05 背景:~ 1.00
1.05 1.00 1.00100% 0.51219
1.05 1.00
MPMS XL 、 VSM
信号:~ 0.10 背景:~ 1.00
0.10 1.00 1.00100% 0.0909
0.10 1.00
114
理想情况的响应曲线
如何判断样品的安装质量( 3 )响应曲线:圆柱体样品
D
H
2 3 4:12 , , ,
8 8 8 8
D D D DSampling
上下两个表面各取 48个点计算(均匀磁化)
D (mm) 1.0 2.0 3.0 4.0 5.0
L (mm) 0.048 0.096 0.144 0.197 0.236
110
116
超导量子磁强计的操作
L L L
两端法:外加电流,测电压(电流与电压共线) 四端法:外加电流,测电压(电流与电压不共线) 两端法:外加电压,测电流(电流与电压共线) van de Pauw 法: 霍耳效应测量:
• 样品的安放:电性(接触)测量样品
样品安装 4
117
关于电输运的测量• 根本问题-连线、接触点
异质材料之间的接触电势
热电势(温差电势)1
( , ) ( , )( )
high
cold
TB
A hot cold ATA
kE T T d N T
e N T
( )( , ) ln
( )
high
cold
TB A
AB hot cold TB
k N TE T T dT
e N T
( )( ) ln
( )B A
ABB
k T N TE T
e N T
物理存在
热电偶
118
关于电输运的测量• 常见问题-虚焊
清洁表面、助焊剂、超声压焊
• 注意事项-消除温差电势
Meter
同质材料
同质材料两引线应该使用相同材料;异质材料的连接点应该处于相同的温度;同质材料的两端的温度应该相同
电阻 < 0 ?电阻 < 0 ?
IoutIin
V+ V-
环境电噪声
121
超导量子磁强计的维护及注意事项•液氦液面与最大可使用的磁场
100 %
7.0 特斯拉90 %80 %70 %60 %
5.0 特斯拉50 %
1.0 特斯拉40 %
0.1 特斯拉30 %
< 0.01 特斯拉20 %
MPMS 维护 2
122
2 、样品室 保持样品室清洁(准确度)
保证样品杆密封(下页)
超导量子磁强计的维护及注意事项
He
1 、控制用计算机 严禁修改MPMSR2快捷方式的设置
软盘必须查 /杀病毒
MPMS 维护 3
123
超导量子磁强计的维护及注意事项• 保持样品腔的清洁(验证、检查)
MPMS 维护 4
1 、在样品杆上安装一支干净的空吸管;
2 、设定磁场 1.0 T (闭环);
3 、测量 M ~ T 曲线( 1.8 K ~ 300 K );
4 、验证。
T
M
~ 108 emu
128
举轻若重• 液氦的价格
2000 年:~ 50 元 / 升; 2007 年: 80元 / 升; 2009 年:~ 200元 / 升
• 氦的密度
400元 / 升
氦气 (273 K, 1 atm) : 0.178 47 g/L ;液氦: 0.124 98 kg/L
氦气 (273 K, 1 atm) : 5 603 L/kg ;液氦: 8.001 3 L/kg
1 kg液氦~ 8 L液氦; 1 L液氦 ~ 700 L氦气
• 人的肺活量:~ 3.5 L 1 块钱!
~ 15 呼吸 / 分钟
135
剔除异常值的方法• 国家标准
GB/T 4883-1985
《数据的统计处理和解释 正态样本异常值的判断和处理》GB/T 8056-1987
《数据的统计处理和解释 指数样本异常值的判断和处理》
检出异常值的个数不超过 1 :Grubbs 检验法、 Dixon 检验法
检出异常值的个数上限大于 1:
偏度-峰度检验法、 Dixon 检验法
观测值个数 3
MPMS XL :Multiple Measure
136
实验标准偏差Bessel 公
式n次测量结果: x1, x2, …, xi, …, xn
1
1 n
ii
xn
x
算术平均值:
2
1
1
1
n
iin
s x xx
实验(样本)标准偏差:
2
1
2
1
2
1
2
11
1
1
1
n
ii
n
ii
n
ii
s x s x x
s x s x
xn
nxn
x
n
的等价表达式1:
的等价表达式2:
单次测量的分散性
137
实验标准偏差Bessel 公
式n= 2 : x1, x2
1 2
2x
x x算术平均值:
1 2
1
2i ix x x x x 单次测量的偏差:
1 2
1
2x x xs 实验标准偏差:
1
2ix s x 判据:
或者都保留或者都剔除
138
为什么• 两个数据点 x1= 1.456 9 、 x2= 2.038 7
1 2 1.747 82
xx x
算术平均值:
1 2 1 2
10.290 9
2x x x x 单次测量的偏差:
1 2
1 0.581 80.411 4
2 2x xs x 实验标准偏差:
i kx s x 判据: 2
2k