Interplay of metamagnetic and structural transitions in Ca$_{2-x}$Sr$_x$RuO$_4$

TL;DR

This paper presents a mean-field model that reproduces the phase diagram and critical metamagnetic behavior of Ca$_{2-x}$Sr$_x$RuO$_4$, highlighting the interplay between metamagnetic and structural transitions.

Contribution

It introduces a microscopic mean-field model that captures the key features of metamagnetism and structural transitions in Ca$_{2-x}$Sr$_x$RuO$_4$, aligning with experimental phase diagrams.

Findings

Reproduces the experimental T-x phase diagram.

Explains the metamagnetic transition and magnetostriction effects.

Provides a basis for understanding quantum critical behavior in ruthenates.

Abstract

Metamagnetism in layered ruthenates has been interpreted as a novel kind of quantum critical behavior. In an external magnetic field, Ca$_{2-x}$Sr$_x$RuO$_4$ undergoes a metamagnetic transition accompanied by a pronounced magnetostriction effect. In this paper we present a mean-field study for a microscopic model that naturally reproduces the key features of this system. The phase diagram calculated is equivalent to the experimental $T$-$x$ phase diagram. The presented model also gives a good basis to discuss the critical metamagnetic behavior measured in the system.