Klyushina, E.S.; Reuther, J.; Weber, L.; Islam, A.T.M.N.; Lord, J.S.; Klemke, B.; Mansson, M.; Wessel, S.; Lake, B.: Signatures for Berezinskii-Kosterlitz-Thouless critical behavior in the planar antiferromagnet BaNi2V2O8. Physical Review B 104 (2021), p. 064402/1-18
10.1103/physrevb.104.064402
Open Access Version
Abstract:
We investigate the critical properties of the spin-1 honeycomb antiferromagnet BaNi2V2O8, both below and above the ordering temperature TN using neutron diffraction and muon spin rotation measurements. Our results characterize BaNi2V2O8 as a two-dimensional (2D) antiferromagnet across the entire temperature range, displaying a series of crossovers from 2D Ising-like to 2D XY and then to 2D Heisenberg behavior with increasing temperature. In particular, the extracted critical exponent of the order parameter reveals a narrow temperature regime close to TN , in which the system behaves as a 2D XY antiferromagnet. Above TN , evidence for Berezinsky-Kosterlitz-Thouless behavior driven by vortex excitations is obtained from the scaling of the correlation length. Our experimental results are in accord with classical and quantum Monte Carlo simulations performed for microscopic magnetic model Hamiltonians for BaNi2V2O8.