Anisotropy of the low-temperature magnetostriction of Sr3Ru2O7

TL;DR

This study investigates the low-temperature magnetostriction of Sr3Ru2O7, revealing multiple metamagnetic transitions and symmetry-breaking effects due to uniaxial pressure.

Contribution

It provides high-resolution measurements of magnetostriction in Sr3Ru2O7, uncovering bifurcation of a transition linked to in-plane symmetry breaking.

Findings

Peaks in magnetostriction coefficient at three metamagnetic transitions.

Bifurcation of the third transition below 0.5 K.

Uniaxial pressure influences in-plane symmetry.

Abstract

We use high-resolution capacitive dilatometry to study the low-temperature linear magnetostriction of the bilayer ruthenate Sr$_3$Ru$_2$O$_7$ as a function of magnetic field applied perpendicular to the ruthenium-oxide planes ($B\parallel c$). The relative length change $\Delta L(B)/L$ is detected either parallel or perpendicular to the c-axis close to the metamagnetic region near B=8 T. In both cases, clear peaks in the coefficient $\lambda(B)=d(\Delta L/L)/dB$ at three subsequent metamagnetic transitions are observed. For $\Delta L\perp c$, the third transition at 8.1 T bifurcates at temperatures below 0.5 K. This is ascribed to the effect of an in-plane uniaxial pressure of about 15 bar, unavoidable in the dilatometer, which breaks the original fourfold in-plane symmetry.