Static magnetization of V15 cluster at ultra-low temperatures:: Precise estimation of antisymmetric exchange

In this article, the low-temperature static (adiabatic) magnetization data of the nanoscopic V-15 cluster present in K-6[(V15As6O42)-As-IV(H2O)]center dot 8H(2)O is analyzed. The cluster anion, which attracted much attention in the past, contains a triangular V-3(IV) array causing frustration as a function of applied field and temperature. In the analysis, a three-spin (S = 1/2) model of V-15 was employed that includes isotropic antiferromagnetic exchange interaction and antisymmetric (AS) exchange in the most general form compatible with the trigonal symmetry of the system. It was shown that, along with the absolute value of AS exchange, the orientation of the AS vector plays a significant physical role in spin-frustrated systems. In this context, the role of the different components of the AS in the low-temperature magnetic behavior of V-15 was analyzed, and we were able to reach a perfect fit to the experimental data on the staircaselike dependence of magnetization versus field in the whole temperature range including extremely low temperature. Furthermore, it was possible for the first time to precisely estimate the two components of the AS vector coupling constant in a triangular unit, namely, the effective in-plane component, D, and the perpendicular part, D-n.