# Nonlinear response in strongly correlated systems

- Date
- October 20 at 17:00 - 18:15, 2021 (JST)

- Speaker
- Dr. Robert Peters (Lecturer, Department of Physics, Graduate School of Science, Kyoto University) Edit

- Venue
- via Zoom

- Language
- English

Nonlinear responses in condensed matter are intensively studied because they provide rich information about materials and hold the possibility of being applied in diodes or high-frequency optical devices [1-4]. While nonlinear responses in noninteracting models have been explored widely, the effect of strong correlations on the nonlinear response is still poorly understood.

This talk will introduce a Green's function method to calculate nonlinear conductivities in strongly correlated materials [5-6]. Correlation effects are thereby included by the self-energy of the material. I will then use this method to study the nonlinear conductivities in noncentrosymmetric f-electron systems. The first system is a heavy Fermion system, where a nonreciprocal conductivity appears in the ferromagnetic phase. The nonreciprocal conductivity thereby always occurs perpendicular to the magnetization of the system and has a strong spin dependence, which might be advantageous for spintronic applications. The second system is a model corresponding to the Weyl-Kondo semimetal Ce3Bi4Pd3, in which a giant spontaneous Hall effect without time-reversal symmetry breaking has been observed [7]. This Hall effect can be explained as a nonlinear Hall effect in an inversion-symmetry broken Weyl-semimetal. It has been shown that the nonlinear Hall effect is related to the Berry curvature dipole [4]. Our study shows that the magnitude of the experimentally observed nonlinear Hall effect can be explained by the strong correlations inherent in this f-electron material [8].

*Detailed information about the seminar refer to the email.

## References

- Y Tokura and N Nagaosa, Nature Comm. 9, 3740
- T Morimoto and N Nagaosa, Science Advances 2, DOI: 10.1126/sciadv.1501524
- Q. Ma et al., Nature 565, 337–342
- I Sodemann and L Fu, Rev. Lett. 115, 216806
- Daniel E. Parker, Rev. B 99, 045121
- Y Michishita and R Peters, Rev. B 103, 195133
- S Dzsaber et al., PNAS 118 e2013386118
- A Kofuji, Y Michishita, and R. Peters, Rev. B 104, 085151
- K Shinada and R Peters, in preparation