Fig. 1

Electrically induced polarization switching in the MoS₂/BaTiO₃/SrRuO₃ junction. a, b PFM phase (a) and amplitude (b) images after application of a negative voltage pulse (−5 V, 0.5 s) to the MoS₂ flake. The 12-u.c.-thick BTO film underneath the MoS₂ flake is fully switched to the upward polarization, P_up. c, d PFM phase (c) and amplitude (d) images after application of several positive voltage pulses (+5 V, 0.5 s) to the MoS₂ flake. BTO underneath the MoS₂ flake is fully switched to downward polarization, P_down. The polarization state of the bare BTO film (at the lower right corner) is not affected by the electrical bias. e, f The I–V characteristics of the same junction measured in the dark and during illumination. The tunneling current for the OFF state (P_up) is largely increased under illumination