Heterogeneous spin state in the field-induced phase of volborthite as seen via 51V nuclear magnetic resonance

TL;DR

This study uses 51V NMR to reveal a heterogeneous magnetic state in volborthite under high magnetic fields, showing two distinct Cu spin systems with different fluctuation behaviors.

Contribution

It uncovers the coexistence of two spatially alternating Cu spin states with distinct fluctuation characteristics in the field-induced phase of volborthite.

Findings

Identification of two types of V sites with different decay rates

Observation of a heterogeneous state with alternating spin systems

Detection of anomalous spin fluctuations in one of the Cu spin systems

Abstract

We report results of 51V NMR in the field-induced phase of volborthite Cu3V2O7(OH)dot2H2O, a spin-1/2 antiferromagnet on a distorted kagome lattice. In magnetic fields above 4.5 T, two types of V sites with different spin-echo decay rates are observed. The hyperfine field at the fast decaying sites has a distribution, while it is more homogeneous at the slowly decaying sites. Our results indicate a heterogeneous state consisting of two spatially alternating Cu spin systems, one of which exhibits anomalous spin fluctuations contrasting with the other showing a conventional static order.