direct observation of spin-orbit coupling in iron-based superconductors · direct observation of...
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S.V. Borisenko IFW-Dresden
Direct observation of spin-orbit coupling
in iron-based superconductors
et al. BSCCO TaSe2
LDA band structure and Fermi surface: 1111
S.V. Borisenko IFW-Dresden
S.V. Borisenko IFW-Dresden
Energy scale of 1 eV
SVB et al., PRL (2010)
Superconducting material: LiFeAs
Renormalization ~ 3
Spectra of NaFeAs in a wide energy range
Evtushinsky et al. arXiv S.V. Borisenko IFW-Dresden
High-energy anomaly in iron-based SC
Evtushinsky et al. arXiv S.V. Borisenko IFW-Dresden
High-energy anomaly in iron-based SC
Evtushinsky et al. arXiv S.V. Borisenko IFW-Dresden
Electron scattering rate in ordinary and strongly interacting systems
Evtushinsky et al. S.V. Borisenko IFW-Dresden
Model for high-energy spectral function
Evtushinsky et al. arXiv S.V. Borisenko IFW-Dresden
How to understand the electronic structure on 1 eV energy scale (alternative – DMFT)
Evtushinsky et al.
Experiment Theory = bare band + a2F
=
= +
+
S.V. Borisenko IFW-Dresden
Energy scale of 0.1 eV
BZ
G
(center)
M
(corner)
G M
122
G M G M
kz=p kz=0
S.V. Borisenko IFW-Dresden
Ca
lcu
latio
ns: A
.Y
are
sko
11 111 1111
122 245 (122)
S.V. Borisenko IFW-Dresden
BZ
G
(center)
M
(corner)
G M
122
G M G M
kz=p kz=0
Fermi level
S.V. Borisenko IFW-Dresden
3210
|k|, 1/Å
76.1
76.0
75.9
75.8
75.7
75.6
75.5
eV
Co-SmFeAsO (Tc=16K)
-15 -10 -5 0 5 10 15
deg
25.90
25.85
25.80
25.75
25.70
25.65
25.60
eV
S.V. Borisenko IFW-Dresden
S.V. Borisenko IFW-Dresden
LiFeAs Tc=18K
Pt-BaFe2As2 Tc=20K
K-BaFe2As2
Tc=38K
Pt-Ca-Fe-As Tc=38K
Co-BaFe2As2 Tc=25K
FeSe Tc=8K
Rb-Fe-Se Tc=33K
Co-SmFeAsO Tc=16K
1111 11 111
122 245 (122)
Simple way to understand the electronic structure on 0.1 eV scale
S.V. Borisenko IFW-Dresden
Energy scale of 0.001 eV (gaps)
EF
kF
2D
Bin
din
g e
ne
rgy (
me
V)
Momentum (Å-1)
DA DB
Gaps
S.V. Borisenko IFW-Dresden
Momentum (Å-1)
Mo
me
ntu
m (
Å-1
) B
ind
ing e
ne
rgy (
me
V)
B
A
BZ
Bin
din
g e
ne
rgy (
me
V)
Bin
din
g e
ne
rgy (
me
V)
Momentum (Å-1)
A
B
DA DB
min max
En
erg
y g
ap
(m
eV
) L
EG
(m
eV
)
D ~ D0 + D1 cos(4f)
f
EF
kF
2D
DLEG ~ D – HWHM@kF
Fermi surface angle, f (°)
G
0.20.10.0
-140-120-100-80-60-40-200204060
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
LiFeAs: xy band
SVB et al. Symmetry 12
Ca-NaFe2As2
Evtushinsky et al. PRB 13
LiFeAs
K-FeSe
K-BaFe2As2 SVB et al. Symmetry 12
Evtushinsky et al. PRB 14
Fermi surface
Band structure
„Quasiparticle Tight-Binding Fit“
Your Theory
Gap function from theory Gap function from experiment
S.V. Borisenko IFW-Dresden
More precision is needed !
En
erg
y, (
eV
)
Momentum, A-1
Angle, (°)
LiFeAs: more precision
S.V. Borisenko IFW-Dresden
151050-5-10-15
0.20
0.15
0.10
0.05
0.00
-0.05
151050-5-10-15
0.20
0.15
0.10
0.05
0.00
-0.05
Momentum (ab.un.)
En
erg
y (
eV
)
hn1
LiFeAs: structure near center of BZ
?
hn2
S.V. Borisenko IFW-Dresden
LiFeAs: spin-orbit coupling
Calculations: A. Yaresko
~ 40 meV
What to expect in ARPES spectra
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: kz-dependence
hn – scan (from 80 to 30 eV)
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: photon energy dependence
LDA Experiment
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: kz-resolved electronic structure
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: magnitude of SOC at G
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs – electron pockets
Angle, (°)
Electron pockets
Spin-orbit interaction !
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: magnitude of SOC along at MX
10 meV
Momentum
Momentum
Kinetic energy (eV)
S.V. Borisenko et al. arXiv:1409.8669
T<Tc T>Tc
LiFeAs: SOC does not depend on T
S.V. Borisenko et al. arXiv:1409.8669
LiFeAs: Fermi surface in the center of BZ
S.V.
Bo
rise
nko
et
al. a
rXiv
:14
09
.86
69
LiFeAs: orbital mixing
S.V. Bo
risenko
et al. arXiv:1
40
9.8
66
9
ARPES Group Danil Evtushinsky, Zhonghao Liu, Janek Maletz Experiments Volodymyr Zabolotnyy (U Würzburg), Setti Thirupathaiah, Alex Charnukha (UC San-Diego), Alexander Kordyuk (IMP Kiev) Timur Kim, Moritz Hösch (Diamond Light Source), C. Matt, Ming Shi, Nan Xu (PSI) Single crystals Sai Aswartham, Luminita Harnagea, Anja Wolter, Sabine Wurmehl (IFW-Dresden) Igor Morozov, Masha Roslova (U Moscow), Chengtian Lin (MPI-FKF Stuttgart), Hai-Hu Wen (NLS Beijing), Alexander Vasiliev (U Moscow), Tobias Stürzer, Dirk Johrendt (LMU Munich) Nikolai Zhigadlo, Bertram Batlogg (ETH Zurich) Vladimir Tsurkan, Joachim Deisenhofer (Augsburg U) Zurab Shermadini, A. Krzton-Maziopa, K. Conder, E. Pomjakushina (PSI Villigen) Shanta Saha, Rongwei Hu, Johnpierre Paglione (University of Maryland) Pengcheng Dai‘s group Theory Alexander Yaresko (MPI-FKF Stuttgart) Yan Wang, Andreas Kreisel, Peter Hirschfeld (U Florida), Thomas Maier (Oak Ridge) Doug Scalapino Tetsuro Saito, Seiichiro Onari, Youichi Yamakawa, Hiroshi Kontani (U Nagoya) Felix Ahn, Ilya Eremin (RUB), Andrey Chubukov (UWM) „13-ARPES“ Andrei Varykhalov, Emile Rienks (HZB), Rolf Follath (PSI) Roland Hübel, Jörg Fink, Bernd Büchner (IFW-Dresden)
Thanks to
DFG Grants BO 1912/3-1 (SPP1458), BO1912/2-2, ZA 654/1-1 €
• Iron-based superconductors are „moderately“ correlated systems: far from insulating state but Hubbard bands start to be formed.
• DMFT is a proper theoretical tool to describe electronic structure on 1 eV
energy scale: U and J can be extracted from comparison with ARPES. • Orbital-dependent renormalization strongly modifies the low-energy electronic
structure and Fermi surface given by 3D relativistic LDA band-structure, but all features/dispersions are present.
• Significant spin-orbit interaction defines the Fermi surfaces bearing the largest
gaps in optimally doped materials. • Important details of the electronic structure of iron-based superconductors are
not yet understood.
Conclusions