Local Berry curvature signatures in dichroic angle-resolved photoelectron spectroscopy

Science Advances 6,no. 9, (2020)

Local Berry curvature signatures in dichroic angle-resolved photoelectron spectroscopy

Michael Schüler, Umberto De Giovannini, Hannes Hübener, Angel Rubio, Michael A. Sentef, Philipp Werner

Topologically nontrivial two-dimensional materials hold great promise for next-generation optoelectronic applications. However, measuring the Hall or spin-Hall response is often a challenge and practically limited to the ground state. An experimental technique for tracing the topological character in a differential fashion would provide useful insights. In this work, we show that circular dichroism angle-resolved photoelectron spectroscopy (ARPES) provides a powerful tool which can resolve the topological and quantum-geometrical character in momentum space. In particular, we investigate how to map out the signatures of the local Berry curvature by exploiting its intimate connection to the orbital angular momentum. A spin-resolved detection of the photoelectrons allows to extend the approach to spin-Chern insulators. Our predictions are corroborated by state-of-the art \emph{ab initio} simulations employing time-dependent density functional theory, complemented with model calculations. The present proposal can be extended to address topological properties in materials out of equilibrium in a time-resolved fashion.

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We acknowledge helpful discussion with Peizhe Tang. Furthermore we acknowledge financial support from the Swiss National Science Foundation via NCCR MARVEL and the European Research Council via ERC-2015-AdG-694097 and ERC Consolidator Grant No. 724103. The Flatiron Institute is a division of the Simons Foundation. M. S. thanks the Alexander von Humboldt Foundation for its support with a Feodor Lynen scholarship. M. A. S. acknowledges financial support by the DFG through the Emmy Noether program (SE 2558/2-1).

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