Quantum Phase Transition in Pr2CuO4 to Collinear Spin State in Inclined Magnetic Field: A Neutron Diffraction Observation

TL;DR

This study observes a quantum phase transition in Pr2CuO4 induced by an inclined magnetic field, revealing a shift from orthogonal to collinear spin states driven by pseudodipolar interactions.

Contribution

It reports the first neutron diffraction observation of a quantum phase transition in Pr2CuO4 under inclined magnetic fields, highlighting the role of pseudodipolar interactions.

Findings

Transition from orthogonal to collinear spin phase observed

Transition driven by pseudodipolar interaction

Transition occurs at T=0 as a quantum phase transition

Abstract

In the external field slightly inclined to the $x$- or y-axis of the frustrated tetragonal atiferromagnet Pr2CuO4, a transition is discovered from the phase with orthogonal antiferromagnetic spin subsystems along [1,0,0] and [0,1,0] to the phase with the collinear spins. This phase is shown to be due to the pseudodipolar interaction, and transforms into the spin-flop phase S perp H asymptotically at very high field. The discovered phase transition holds at T=0 and is a quantum one, with the transition field being the critical point and the angle between two subsystems being the order parameter.