SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 94: Topology and Symmetry-Protected Materials

O 94.5: Talk

Friday, March 31, 2023, 11:30–11:45, GER 38

Shift current in the Haldane model: analytic and numerical evaluation — •Javier Sivianes Castaño and Julen Ibañez Azpiroz — Centro de Física de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain

The shift current is a second order optical response which takes place in noncentrosymmetic crystals and is characterized by a DC photocurrent. As realized recently, the shift current is sensitive to the topology of materials [1]. In particular, DFT calculations have predicted a sign change when going through a topological phase transition (TPT) in the bulk crystals BiTeI and CsPbI3 [2]. Here we analyse the shift current in the Haldane model, as a toy model that describes inversion symmetry breaking and features non-trivial topological phases. We derive a simple analytical expression that accounts for the sign change across the TPT by relating it to the inversion of the mass term, in agreement with Ref [3]. We complement our study by a numerical evaluation on a continuum version on the Haldane model [4]. In this description we study the quantitative importance of the off-diagonal matrix elements of the position operator that are commonly discarded in the tight-binding description.

Funding provided by the European Union’s Horizon 2020 research and innovation programme under the European Research Council (ERC) grant agreement No 946629.

[1] T. Morimoto and N. Nagaosa, Sci. Adv. 2, 5 (2016) [2] L. Z. Tan and A. M. Rappe, PRL 116, 237402 (2016) [3] Z. Yan, arXiv:1812.02191 [4] J. Ibañez-Azpiroz et al., PRB 92, 195132 (2015)