Coherent spin-current oscillations in transverse magnetic fields

TL;DR

This paper investigates the coherence and dynamics of transverse spin-currents in a spin-1/2 Heisenberg chain, revealing a novel collective oscillation as a many-magnon effect at low temperatures.

Contribution

It introduces the discovery of a collective many-magnon oscillation in spin-currents, supported by numerical and analytical analysis, expanding understanding of spin dynamics in quantum chains.

Findings

Identification of a collective oscillation at higher frequencies

Analysis of oscillation frequency and decay time versus temperature and magnetic field

Observation of coherent many-magnon effects at low temperatures

Abstract

We address the coherence of the dynamics of spin-currents with components transverse to an external magnetic field for the spin-1/2 Heisenberg chain. We study current autocorrelations at finite temperatures and the real-time dynamics of currents at zero temperature. Besides a coherent Larmor oscillation, we find an additional collective oscillation at higher frequencies, emerging as a coherent many-magnon effect at low temperatures. Using numerical and analytical methods, we analyze the oscillation frequency and decay time of this coherent current-mode versus temperature and magnetic field.