Magnetic excitations and effects of magnetic fields on the spin-Peierls transition in CuGeO$_3$

TL;DR

This paper models magnetic excitations in CuGeO3 using a Heisenberg model with alternating and second neighbor interactions, successfully matching experimental data on dispersion, magnetization, phase diagram, and specific heat.

Contribution

It introduces a refined Heisenberg model that accurately describes magnetic excitations and thermodynamic properties of CuGeO3 during the spin-Peierls transition.

Findings

Good agreement between calculated and experimental excitation dispersion.

Model reproduces magnetization curves and saturation values.

Qualitative match of magnetic phase diagram and specific heat behavior.

Abstract

We analyze the magnetic excitations of a spin-1/2 antiferromagnetic Heisenberg model with alternating nearest neighbor interactions and uniform second neighbor interactions recently proposed to describe the spin-Peierls transition in CuGeO$_3$. We show that there is good agreement between the calculated excitation dispersion relation and the experimental one. We have also shown that this model reproduces satisfactorily the experimental results for the magnetization vs. magnetic field curve and its saturation value. The model proposed also reproduces qualitatively some features of the magnetic phase diagram of this compound and the overall behavior of the magnetic specific heat in the presence of applied magnetic fields.