Talk for the canceled APS March Meeting 2020 in Denver (ppt presentation with animation)

1. ||
Leonardo Degiorgi, Laboratorium für Festkörperphysik,
Department of Physics, ETH Zürich, Switzerland
Unprecedented Optical Anisotropy in
Optimally Doped Iron-Based Superconductors
05.03.2020Leonardo Degiorgi 1

2. ||
Ubiquitous Signatures of Nematic Quantum
Criticality in Optimally Doped Fe-based
Superconductors
05.03.2020Leonardo Degiorgi 2
Kuo et al., Science 352, 958 (2016)

3. ||
Anisotropic Optical Response at 10 K
05.03.2020Leonardo Degiorgi 3
Pal et al., npj Quantum Materials 4, 3 (2019)

4. ||
Temperature Dependence of the Anisotropic Optical
Response: Reflectivity and Dichroism
05.03.2020Leonardo Degiorgi 4
p(bar)
10 30 50 70 90
0.0
0.4
0.8
1.2
0.8(r)
0.4(r)
0(r)
ω0=600 cm-1
0
1
2
3
ΔRRatio(T,p;ω0)
Temperature (K)
–200
–100
0
100
200
Δσ1(ω,T;p)=σ1
a-σ1
b(Ωcm)-1
300 500 700 900
(b)
1.2 bar
Temperature(K)
300 500 700 900
10
20
30
40
50
60
(c)
0(r) bar
300 500 700 900
10
20
30
40
50
60
(a)
0 bar
Temperature(K)
Frequency (cm-1)Frequency (cm-1) Frequency (cm-1)
DRratio w( ) »1-
Ra w( )
Rb w( )
Pal et al., npj Quantum Materials 4, 3 (2019)

5. ||
Anisotropic Optical Conductivity and
Superconducting Gap
05.03.2020Leonardo Degiorgi 5
Frequency (cm-1)
σ1(ω)(Ωcm)-1
200 400 600 800
0
500
1000
(a)
a-axis
b-axis
10 K, 1.2 bar
Frequency (cm-1)
σ1(ω)(Ωcm)-1
200 400 600 800
0
500
1000
(a)
a-axis
b-axis
10 K, 1.2 bar
Frequency (cm-1)
σ1(ω)(Ωcm)-1
200 400 600 800
0
500
1000
(a)
a-axis
b-axis
10 K, 1.2 bar
Frequency (cm-1)
σ1(ω)(Ωcm)-1
200 400 600 800
0
500
1000
(a)
a-axis
b-axis
10 K, 1.2 bar
Temperature (K)
2Δ1(cm-1)
0
100
200
(b)
a-axis
b-axis
0 20 40 60
0
100
200
a-axis
b-axis
2Δ2(cm-1)

6. ||
Conclusion
05.03.2020Leonardo Degiorgi 6
ω (cm-1)
200 400 600 800
0.96
0.98
1.00
1.02
1.04
Ra/Rb(ω,p,T)
(a)
T<Tc
0 bar
1.2 bar
0(r) bar
Ra/Rb(ω,p,T)
0.96
0.98
1.00
1.02
1.04
(b)
T~Tc
0 bar
1.2 bar
0(r) bar
Pal et al., npj Quantum Materials 4, 3 (2019)

7. ||
Acknowledgements
Samples
I.R. Fisher
J.G. Analytis
J.-H. Chu
H.-H. Kuo
(Stanford University)
Theory
M. Schütt
R.M. Fernandes
A.V. Chubukov
(University of
Minnesota)
J. Schmalian
(University of
Karlsruhe)
05.03.2020Leonardo Degiorgi 7
Manuel
Chinotti
Anirban Pal

8. ||Leonardo Degiorgi 05.03.2020 8