51V-NMR study of antiferromagnetic state and spin dynamics in the quasi-one-dimensional BaCo2V2O8

TL;DR

This study uses 51V-NMR to investigate the static and dynamic magnetic properties of the quasi-one-dimensional antiferromagnet BaCo2V2O8, revealing complex magnetic behavior influenced by quantum fluctuations and spin dynamics.

Contribution

The paper provides detailed NMR analysis of magnetic order and spin fluctuations in BaCo2V2O8, highlighting the incomplete AF order near TN and the relation between relaxation rates and susceptibility.

Findings

Identification of two V sites with different internal magnetic fields.

Observation of incomplete AF order influenced by quantum fluctuations.

Correlation between 1/T1T and magnetic susceptibility indicating AF spin fluctuations.

Abstract

We report on our 51V-NMR study of static and dynamical magnetic properties in the quasi-one-dimensional antiferromagnet BaCo2V2O8. Although the NMR spectrum shows well-defined antiferromagnetic (AF) order in the N\'eel ground state, the AF characteristic from the NMR spectrum is incomplete between 3.5 K and TN= 5.4 K, which could be affected by quantum spin fluctuations. The AF NMR spectrum indicates two V sites experiencing different magnetic field magnitudes, HA1=2.1 kOe and HA2=3.8 kOe. These internal fields could be explained by accounting for the classical and the pseudo-dipolar fields from Co2+ spins with a proposed magnetic structure based on the neutron diffraction measurements. In the paramagnetic state, the nuclear spin relaxation is dominated by AF spin fluctuations through the dipolar-type coupling between V and surrounding Co2+ ions. The linear relation between the nuclear spin-lattice relaxation rate 1/T1T and the magnetic susceptibility chi indicates that the Q component of magnetic susceptibility chi(Q) is roughly proportional to chi, where Q is the AF wave number. A change in slope of 1/T1T with respect to \chi around 150 K suggests a change in the AF spin fluctuation spectrum.