An Effective Spin Hamiltonian Approach to Metamagnetism - I

TL;DR

This paper introduces a minimal spin Hamiltonian model for itinerant electron metamagnetism, linking critical fields and susceptibilities, and extends it to account for deviations observed in correlated materials.

Contribution

It presents a simple yet effective spin Hamiltonian model that captures key features of metamagnetism and relates thermodynamic properties to experimental observations.

Findings

Critical field proportional to susceptibility peak temperature

Model reproduces thermodynamic behavior of heavy fermion systems

Extensions account for deviations from minimal behavior

Abstract

We describe a minimal model, based on a spin only Hamiltonian with a single energy scale for itinerant electron metamagnetism. Within this model the metamagnetic critical field is directly proportional to the temperature where a peak in the linear susceptibility occurs which in turn is related in a simple manner to the temperature where the nonlinear susceptibilities also peak. The spin dependent thermodynamic properties are derived in a straightforward manner and bear a striking resemblance to observations in such strongly correlated systems as heavy fermion materials. We also consider extensions of the model by including effects such as a mean field to encompass observed deviations from a minimal metamagnetic behavior.