direct observation of spin-orbit coupling in iron-based superconductors · direct observation of...

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