Efficient spin accumulation carried by slow relaxons in chiral tellurium

TL;DR

This paper demonstrates that in chiral tellurium, slow relaxons enable highly efficient charge-to-spin conversion and long-distance spin transport, overcoming rapid spin relaxation caused by strong spin-orbit coupling.

Contribution

The study reveals that relaxons in chiral tellurium facilitate efficient spin conversion and transport, a novel mechanism not previously exploited in spintronics.

Findings

Achieved 50% charge-to-spin conversion efficiency.

Identified relaxons as slow collective relaxation modes.

Demonstrated long spin lifetime in chiral tellurium.

Abstract

Efficient conversion between charge currents and spin signals is crucial for realizing magnet-free spintronic devices. However, the strong spin-orbit coupling that enables such a conversion, causes rapid relaxation of spins, making them difficult to transport over large length scales. Here, we show that spin-momentum entanglement at the Fermi surface of chiral tellurium crystals leads to the appearance of slow collective relaxation modes. These modes, called relaxons, resemble the persistent spin helix, a collective spin-wave excitation with extended lifetime observed in quantum wells. The slow relaxons dominate the electrically generated spin and orbital angular momentum accumulation in tellurium and make it possible to combine a very high 50% conversion efficiency with a long spin lifetime. These results, obtained from the exact solution of the Boltzmann transport equation, show that chiral crystals can be used for highly efficient generation and transmission of spin signals over long distances in spintronic devices.