Field-enhanced quantum fuctuation in S=1/2 frustrated square lattice

TL;DR

This study introduces a new S=1/2 frustrated square lattice compound exhibiting unusual magnetic behavior, including gradual magnetization increase and a 1/2-plateau, driven by field-enhanced quantum fluctuations.

Contribution

It reports the synthesis and analysis of a novel frustrated square lattice compound with complex interactions, revealing unique magnetic phenomena not previously observed.

Findings

Gradual magnetization increase under magnetic field

Observation of a 1/2-plateau-like behavior

Support from NMR measurements indicating quantum fluctuations

Abstract

We present a new model compound with the S = 1/2 frustrated square lattice composed of the charge-transfer salt (o-MePy-V)PF6. Ab initio calculations indicate the formation of an S = 1/2 square lattice, in which six types of nearest-neighbor ferromagnetic- and antiferromagnetic interactions cause frustration. By applying a magnetic field, we observe an unusually gradual increase of magnetization and a subsequent 1/2-plateau-like behavior. A numerical analysis using the tensor network method qualitatively demonstrates such behaviors and suggests a collinear ordered state and a field-enhanced quantum fluctuation. Furthermore, the local magnetization and T1^-1 probed by nuclear magnetic resonance measurements support these findings.