JETP Letters: issues online

We investigate electron transport along the surface of WTe₂ three-dimensional single crystals, which are characterized by the coexistence of Weyl semimetal conductivity and ferroelectricity at room temperature. We find that non-linear behavior of dV/dI(I) WTe₂ differential resistance is accompanied by slow relaxation process, which appears as the dV/dI(I) dependence on the sign of the current change. This observation is confirmed by direct investigation of time-dependent relaxation curves. While strongly non-linear differential resistance should be expected for the zero-gap WTe₂, the slow relaxation in transport is very unusual for well-conducting semimetals at room temperature. We establish, that non-monotonic dependence of the amplitude of the effect on driving current Δ dV/dI(I) well corresponds to the known Sawyer-Tower's ferroelectric hysteresis loop. The possibility to induce polarization current by source-drain field variation is unique for WTe₂, since it is a direct consequence of the coexistence of ferroelectricity and metallic conduction. This conclusion is also confirmed by gate voltage dependencies, so our results can be understood as a direct demonstration of WTe₂ ferroelectric behavior in charge transport experiment.