Quantum critical metamagnetism of Sr3Ru2O7 under hydrostatic pressure

TL;DR

This study investigates how hydrostatic pressure affects the quantum critical end point in Sr3Ru2O7, revealing new features near the QCEP and challenging previous assumptions about the order parameter.

Contribution

It provides the first detailed pressure dependence of the metamagnetic critical end point and uncovers new phenomena near the quantum critical end point in Sr3Ru2O7.

Findings

T* decreases monotonically with pressure to zero at Pc~13.6 kbar

New features such as slope change and subsidiary maxima appear near Pc

The susceptibility peak remains sharp in field but broadens in temperature near QCEP

Abstract

Using ac susceptibility, we have determined the pressure dependence of the metamagnetic critical end point temperature T* for field applied in the ab-plane in the itinerant metamagnet Sr3Ru2O7. We find that T* falls monotonically to zero as pressure increases, producing a quantum critical end point (QCEP) at Pc~13.6 kbar. New features are observed near the QCEP -- the slope of T* vs pressure changes at ~12.8 kbar, and weak subsidiary maxima appear on either side of the main susceptibility peak at pressures near Pc -- indicating that some new physics comes into play near the QCEP. Clear signatures of a nematic phase, however, that were seen in field-angle tuning of T*, are not observed. As T* is suppressed by pressure, the metamagnetic peak in the susceptibility remains sharp as a function of applied magnetic field. As a function of temperature, however, the peak becomes broad with only a very weak maximum, suggesting that, near the QCEP, the uniform magnetization density is not the order parameter for the metamagnetic transition.