Metamagnetic quantum criticality in Sr3Ru2O7 studied by thermal expansion

TL;DR

This study investigates the thermal expansion of Sr3Ru2O7 near its quantum critical point, revealing entropy accumulation and metamagnetic transitions consistent with itinerant quantum criticality theory.

Contribution

It provides experimental evidence of quantum critical behavior in Sr3Ru2O7 through thermal expansion measurements under magnetic fields.

Findings

Entropy accumulates near 8 Tesla indicating a quantum critical point.

Two first-order metamagnetic transitions bound a high-entropy regime.

Thermal expansion behavior aligns with itinerant theory predictions for 2D metamagnetic quantum criticality.

Abstract

We report low-temperature thermal expansion measurements on the bilayer ruthenate Sr$_3$Ru$_2$O$_7$ as a function of magnetic field applied perpendicular to the Ruthenium-oxide planes. The field-dependence of the c-axis expansion coefficient indicates the accumulation of entropy close to 8 Tesla, related to an underlying quantum critical point. The latter is masked by two first-order metamagnetic transitions which bound a regime of enhanced entropy. Outside this region the singular thermal expansion behavior is compatible with the predictions of the itinerant theory for a two-dimensional metamagnetic quantum critical end point.