Ground state of the Kagome-like S=1/2 antiferromagnet, Volborthite Cu3V2O7(OH)2.2H2O

TL;DR

This study investigates the ground state of the highly frustrated S=1/2 kagome-like antiferromagnet in Volborthite, revealing a complex mixture of spin configurations and significant quantum fluctuations that influence magnetic ordering.

Contribution

It provides detailed experimental insights into the ground state of Volborthite, highlighting the presence of short-range order and quantum fluctuations in a highly frustrated kagome lattice.

Findings

Broad magnetic transition below 2K observed

20% of spins show short-range order, possibly of 2 type

Only 40% of Cu moments are frozen, indicating strong quantum fluctuations

Abstract

Volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagome-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4K$\pm$0.2K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% correspond to a well defined short range order, possibly of the $\sqrt{3} \times \sqrt{3}$ type. While the freezing involve all the Cu$^{2+}$ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.