Extended Data Fig. 2: Contrasting behaviours of in-plane and out-of-plane photocurrents as a result of the gyrotropic order in 1T-TiSe2.
From: Spontaneous gyrotropic electronic order in a transition-metal dichalcogenide
a, b, Optical image (a) and schematic illustration (b) of a TiSe2 photoactive device that can detect both the in-plane and out-of-plane photocurrents independently. The electrodes are labelled by capital letters. c, Spatial map of the out-of-plane photocurrent Iz between electrodes G–A at T = 100 K. d, Polarization-dependent Iz data at T = 100 K. The measured photocurrent Iz is consistent with the results of previous devices (Figs. 2, 3). A single peak is observed in c that roughly covers the device. This peak consists of two independent signals: the polarization-independent background, which arises from the photothermoelectric effect and exists at all temperatures, and the polarization-dependent CPGE signal (d), which depends on chiral induction and appears only at low temperatures. e–h, Same as c, d, but for the in-plane photocurrent Ix,y between electrodes C–H (e, f) and C–D (g, h). Ix,y shows distinctly different properties from Iz. No in-plane CPGE is observed (f, h). The polarization-independent signal shows a bipolar spatial configuration (e, g): Ix,y changes sign as the beam spot is scanned from one contact to the other. This bipolar spatial configuration, which has been widely observed in other in-plane photocurrent studies23, further confirms that the polarization-independent signals are photothermoelectric currents at the contact–sample junctions. Scale bars, 25 μm. All data in this figure were collected after RCP chiral induction with an induction power of 30 mW.
