Photocurrent response in parity-time symmetric current-ordered states

There is growing interest in the photo-induced generation of rectified current, namely photocurrent phenomenon. While the response was attributed to noncentrosymmetric structures of crystals, the parity violation accompanied by the magnetic ordering, that is, magnetic parity violation, is recently attracting attention as a platform for a photocurrent generator. In this paper, we investigate the photocurrent response in the current-ordered phase, realizing the magnetic parity violation without the spin degree of freedom, although prior studies focused on the parity-violating spin structure. The loop-current order breaks the inversion symmetry while preserving the parity-time-reversal symmetry. With a model of Sr$_2$IrO$_4$, we demonstrate the linearly and circularly polarized light-induced photocurrent responses in the current-ordered state. Each photocurrent has a distinct tolerance of the scattering rate according to the mechanism for the photocurrent creation. The predicted photocurrent response is comparable to that in prototypical semiconductors. We propose a probe to detect the hidden-ordered phase in Sr$_2$IrO$_4$ by the photocurrent response.

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