Nonvolatile electrical switching of nonreciprocal transport in ferroelectric polar metal WTe2

Nonreciprocal charge transport in junction-free devices has gained strong research interest recently, due to its capabilities to reveal new quantum physics and potential in outperforming traditional junction-based nonreciprocal devices. While nonreciprocal transport has been reported in a wide range of materials due to various exotic physics, the direction of nonreciprocity is mostly fixed. A key capability that has not been established is the active control of the direction of nonreciprocity. Here by taking advantage of the unique and intrinsic coexistence of switchable ferroelectricity and magnetochiral anisotropy in few-layer polar metal WTe2, we demonstrate nonvolatile electrical switching of nonreciprocal transport. The direction of nonreciprocal transport is reversed upon electrical switching of the ferroelectric polarization, and the switching is nonvolatile, i.e., it can be maintained even without external voltages. The nonreciprocal transport in few-layer WTe2 is also highly tunable with electrostatic doping. Theoretical calculations reveal a nontrivial Drude-like mechanism for the reciprocity, with significant band geometrical contribution due to interband coherence. The demonstration of nonvolatile electrically switchable nonreciprocal transport provides a novel route to switch topological quantum physics and paves the way to programmable junction-free diodes.