FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi...
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Transcript of FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi...
![Page 1: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/1.jpg)
FLEX Study of ’-(ET)2AuCl2
Hiori Kino (National institute for materias science)Hiroshi Kontani (Nagoya Univ.)
Tsuyoshi Miyazaki (National institute for materials science)
![Page 2: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/2.jpg)
Motivation
’-(ET)2ICl2 ’-(ET)2AuCl2*
Structure
ambient pressure
under applied pressure
--- Almost the same ET stacking---
AF insulator insulator
superconductivity insulator
Why?*Taniguchi, et al., JPSJ 74, 1370 (2005).
![Page 3: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/3.jpg)
Dimensionality of Fermi surfaces
Quasi-1D Quasi-1D
Electronic structure (first-principles study by Miyazaki et al,)
’-(ET)2ICl2 ’-(ET)2AuCl2
Ambient pressure
Applied pressure 3D2D
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0GPa 4GPa 8GPa
12GPa 16GPa 20GPa
Fermi surfaces (tight binding fit)
a*
c*
b*
![Page 5: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/5.jpg)
Q?
higher dimensionality of Fermi surface stabilize AF phase in ’-(ET)2AuCl2?
Methods:Hamiltonian:•tight binding model (ET dimer model) •effective on-site (intra-dimer) Coulomb interaction
Perturbation theory:•FLEX-approximation
nnUcctH effjiij
![Page 6: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/6.jpg)
Results
TN
No SC phase
Ueff=0.5eV
![Page 7: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/7.jpg)
Discussion
AF
SC Pressure
Tem
pera
t ure
’-(ET)2ICl2
Suppress(→1D)
2D
Pressure
Tem
pera
ture
AF
’-(ET)2AuCl2
Enhance(2D→3D)Suppress
(→1D)No SC phase
Fermi surface nesting?U?
a*
c*
b*
TN
![Page 8: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/8.jpg)
intralayerdimensionality
tem
pera
ture
TN
TSC
interlayer
dimensionality
Discussion (2)
TN
PressureAuCl2
PressureICl2
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Fermi surfaces (extended zone)
12GPa 20GPa
![Page 10: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/10.jpg)
Summary
’-(ET)2AuCl2
AF phase is stabilized under applied pressures.
Reason:Higher-dimensionalityU → better FS nesting
![Page 11: FLEX Study of ’-(ET) 2 AuCl 2 Hiori Kino ( National institute for materias science ) Hiroshi Kontani ( Nagoya Univ. ) Tsuyoshi Miyazaki ( National institute.](https://reader035.fdocuments.net/reader035/viewer/2022062306/5a4d1b097f8b9ab059989a20/html5/thumbnails/11.jpg)
Fermi surfaces (2D, b-axis-off)
0GPa 4GPa 8Gpa
12GPa 16GPa 20GPa
a*
c*
→Destabilize AF?