Spin ice in a field: quasi-phases and pseudo-transitions

TL;DR

This paper analyzes the thermodynamics of spin ice magnets in a magnetic field using the Bethe-Peierls approximation, revealing pseudo-phases and pseudo-transitions that mimic phase behavior without true phase transitions.

Contribution

It provides an analytical framework for understanding field-induced anomalies and pseudo-phases in spin ice, aligning well with simulations and experiments.

Findings

Identification of pseudo-phases with distinct spin fluctuation characteristics

Analytical description of sharp anomalies in thermodynamic quantities

Lines of pseudo-transitions in the H-T plane

Abstract

Thermodynamics of the short-range model of spin ice magnets in a field is considered in the Bethe - Peierls approximation. The results obtained for [111], [100] and [011] fields agrees reasonably well with the existing Monte-Carlo simulations and some experiments. In this approximation all extremely sharp field-induced anomalies are described by the analytical functions of temperature and applied field. In spite of the absence of true phase transitions the analysis of the entropy and specific heat reliefs over H-T plane allows to discern the "pseudo-phases" with specific character of spin fluctuations and define the lines of more or less sharp "pseudo-transitions" between them.