Hydrostatic pressure effects on the magnetic structure and critical behaviour of the quasi-two-dimensional S=1 antiferromagnet BaNi2V2O8

We propose to study the hydrostatic pressure effects on the critical behavior of the S=1 honeycomb antiferromagnet (AFM) BaNi2V2O8 which we found to be an ideal physical realization of a quasi-2D AFM over a wide temperature range in vacuum. Depending on the temperature regime, BaNi2V2O8 behaves as a 2D XY, 2D XXZ or 2D Heisenberg magnet. In the 2D XY regime BaNi2V2O8 reveals signatures of Berezinskii-Kosterlitz-Thousless (BKT) criticality. Because T_BKT estimated in BaNi2V2O8 be lower than T_N, the quasi-ordered state of vortex/anti-vortex pairs is hidden by long-range magnetic order so that only signatures for the decomposed vortex/anti-vortex pairs were experimentally observed just above T_N. Thus, searching for the experimental tool which can customize T_N, T_BKT and the 2D XY regime making BKT phenomena easier experimentally accessible in quasi-2D solid-state magnets, such as BaNi2V2O8, is an important scientific task. Here, we propose to explore the hydrostatic pressure effects on magnetic structure and critical exponent of BaNi2V2O8, to probe the hydrostatic pressure effects on critical bahaviour in quasi-2D magnets for the first time to our knowledge.