Quantum spin pump on a finite antiferromagnetic chain through bulk states

TL;DR

This paper demonstrates a theoretical model for a quantum spin pump in a finite antiferromagnetic chain, showing how adiabatic changes induce quantized spin transport via bulk states.

Contribution

It introduces a novel approach using bosonization and sine-Gordon equations to realize a spin pump in a finite antiferromagnetic chain.

Findings

Quantized spin transport achieved through adiabatic phase variation.

Static soliton solutions are compatible with physical boundary conditions.

Bulk states facilitate spin transfer between chain ends.

Abstract

We studied the possibility of the spin pump in a S=1/2 antiferromagnetic chain. The spin chain is mapped into a fermion system and bosonization is utilized to transform the equation of motion to a sine-Gordon equation. The sine-Gordon equation on a finite chain with different boundary conditions is solved. Among numerous solutions, the static soliton is compatible with the original physical system. By varying adiabatically a angle in the phase space composed of applied electric and magnetic fields, the spin states change between the Neel state and dimer state and a quantized spin is transported by the bulk state from one end of the system to the other.