Giant Spin Current Rectification Due to the Interplay of Negative Differential Conductance and a Non-Uniform Magnetic Field

Abstract

In XXZ chains with large enough interactions, spin transport can be significantly suppressed when the bias of the dissipative driving becomes large enough. This phenomenon of negative differential conductance is caused by the formation of two oppositely polarized ferromagnetic domains at the edges of the chain. Here, we show that this many-body effect, combined with a non-uniform magnetic field, can allow for a high degree of control of the spin current. In particular, by studying all of the possible shapes of local magnetic fields potentials, we find that a configuration in which the magnetic field points up for half of the chain and down for the other half, can result in giant spin-current rectification, for example, up to 108 for a system with only 8 spins. Our results show clear indications that the rectification can increase with the system size.

Non-equilibrium boundary driven quantum systems: models, methods and properties

“…In fact, the presence of long range interaction opposes the formation of two large and opposite ferromagnetic domains at the edges of the system, thus resulting in a more gradual spin magnetization profile in the system. Particularly chosen local potentials can also significantly reduce the negative differential conductivity for one bias and reinforce it for the opposite bias, thus resulting in strong spin current rectification (Lee et al, 2020), as discussed in IV.B.…”

“…An XXZ spin chain which also shows large spin current rectification, and works under the same principle as the one just discussed, is an XXZ chain with homogeneous anisotropy along the system, but with a local magnetic field which points in one direction for half the chain and in the opposite direction for the other half of the chain (Lee et al, 2020). Also in this scenario the system in one bias can turn into an insulator for large enough interaction strengths because the steady state is a gapped eigenstate of the Hamiltonian.…”