Randomness Effect on the Temperature Dependence of the Finite Field Magnetization of a One-Dimensional Spin Gapped System

TL;DR

This study examines how randomness in a magnetic field affects the temperature-dependent magnetization of a one-dimensional spin system with a gap, revealing diverse behaviors influenced by system parameters.

Contribution

It provides an exact calculation of the random-averaged free energy for the bond-alternating XY model under Lorentzian-distributed magnetic fields, elucidating the impact of randomness on magnetization.

Findings

Magnetization behavior varies with system parameters.

Exact thermodynamic quantities are derived.

Randomness significantly influences temperature dependence.

Abstract

We investigate the temperature dependence of the finite-field magnetization of the S=1/2 bond-alternating XY model in the Random magnetic field along the z-direction having the Lorentzian distribution. The random-averaged free energy can be exactly calculated, which enables us to obtain the thermodynamical quantities. The temperature dependence of the finite-field magnetization shows various behaviors depending on the parameters $\delta$ and $\Gamma$, where $\delta$ and $\Gamma$ are the bond-alternation parameter and the Lorentzian distribution parameter, respectively.