Optical absorption measurement of spin Berry curvature and spin Chern marker

Wei Chen

doi:10.1088/1361-648x/acba72

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arXiv · 2207.02973

Optical absorption measurement of spin Berry curvature and spin Chern marker

Wei Chen

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Abstract

In two-dimensional time-reversal symmetric topological insulators described by Dirac models, the ${\mathbb Z}_{2}$ topological invariant can be described by the spin Chern number. We present a linear response theory for the spin Berry curvature that integrates to the spin Chern number, and introduce its spectral function that can be measured at finite temperature by momentum- and spin-resolved circular dichroism, which may be achieved by pump-probe type of experiments using spin- and time-resolved ARPES. As a result, the sign of the Pfaffian of the ${\mathbb Z}_{2}$ invariant can be directly measured. The spin Chern number expressed in real space yields a spin Chern marker, whose spatial variation may be measured by circular dichroism and spin-resolved photoemission with a spatial resolution. A spin Chern correlator and a nonlocal spin Chern marker are further proposed to characterize the quantum criticality near topological phase transitions, which are shown to take the form of overlaps between spin-selected Wannier states.

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Wei Chen. 2022-07-06. Optical absorption measurement of spin Berry curvature and spin Chern marker. https://doi.org/10.1088/1361-648x%2Facba72

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