Non-reciprocal Magnetoresistances in Chiral Tellurium

Materials with broken fundamental symmetries, such as chiral crystals, provide a rich playground for exploring unconventional spin-dependent transport phenomena. The interplay between a material’s chirality, strong spin-orbit coupling, and charge currents can lead to complex non-reciprocal effects, where electrical resistance depends on the direction of current and magnetic fields. In this study, we systematically investigate the angular dependencies of magnetoresistance in single-crystalline chiral Tellurium (Te). We observe distinct non-reciprocal magnetoresistances for magnetic fields applied along three orthogonal directions: parallel to the current along the chiral axis (z), in the sample plane but perpendicular to the current (y), and out of the sample plane (x). Through detailed analysis of the chirality- and thickness-dependence of the signals, we successfully disentangle multiple coexisting mechanisms. We conclude that the Edelstein effect, arising from the chiral structure’s radial spin texture, is responsible for the non-reciprocity along the z-axis. In contrast, the chirality-independent signal along the y-axis is attributed to the Nernst effect, and the non-reciprocity along the x-axis may originate from intrinsic orbital magnetizations. These findings elucidate the complex interplay of spin, orbital, and thermal effects in Te, providing a complete picture of its non-reciprocal transport properties.

💡 Research Summary

In this work the authors present a comprehensive study of non‑reciprocal (direction‑dependent) magnetoresistance in single‑crystalline, chiral tellurium (Te). By fabricating devices in which an alternating current is applied along the crystallographic c‑axis (the chiral axis, denoted as z) and by rotating an external magnetic field in three orthogonal planes (B‖z, B‖y, and B‖x), they map out the angular dependence of the longitudinal resistance. With a pure AC drive the first‑harmonic voltage Vω is symmetric with respect to field reversal, but the addition of a dc offset (±Idc) produces a clear non‑reciprocal component: Vω(+Idc)≠Vω(−Idc) and the sign of the difference reverses when the current polarity is flipped. The same non‑reciprocal behavior is observed in the second‑harmonic voltage V2ω, which scales linearly with both the current amplitude I0 and the magnetic field magnitude, providing an independent verification of the effect.

The authors model the resistance as

R(I,B)=R0