Quantum dissipation theory of slow magnetic relaxation mediated by domain-wall motion in one-dimensional chain compound [Mn(hfac)_{2}BNO_{H}}]

TL;DR

This paper develops a quantum dissipation model to explain slow magnetic relaxation in a one-dimensional ferrimagnetic chain compound, linking domain-wall dynamics with experimental magnetization and susceptibility observations.

Contribution

It introduces a quantum dissipation framework for domain-wall motion in magnetic chains, providing a theoretical explanation for experimentally observed slow relaxation phenomena.

Findings

Good agreement between model and experimental magnetization data

Identification of domain-wall kink motion as key to relaxation dynamics

Correlation of relaxation times with ac-susceptibility measurements

Abstract

Based on a quantum dissipation theory of open systems, we present a theoretical study of slow dynamics of magnetization for the ordered state of the new molecule-based magnetic complex [Mn(hfac)_{2}BNO_{H}] composed from antiferromagnetically coupled ferrimagnetic (5/2,1) spin chains. Experimental investigations of the magnetization process in pulsed fields have shown that this compound exhibits a metamagnetic AF-FI transition at a critical field in the order of the interchain coupling. A strong frequency dependence for the ac-susceptibility has been revealed in the vicinity of the AF-FI transition and was associated with an AF-FI interface kink motion. We model these processes by a field-driven domain-wall motion along the field-unfavorable chains correlated with a dissipation effect due to a magnetic system-bath coupling. The calculated longitudinal magnetization has a two-step relaxation after the field is switched off and are found in good agreement with the experiment. The relaxation time determined from the imaginary part of the model ac-susceptibility agrees qualitatively with that found from the remanent magnetization data.