The linear and non-linear magnetic response of a tri-uranium single molecule magnet

Abstract

We report here low temperature magnetization isotherms for the single molecule magnet, (UO2-L)3. By analyzing the low temperature magnetization in terms of M = χ1B + χ3B3 we extract the linear susceptibility χ1 and the leading order nonlinear susceptibility χ3. We find that χ1 exhibits a peak at a temperature of T1 = 10.4 K with χ3 also exhibiting a peak but at a reduced temperature T3 = 5 K. At the lowest temperatures the isotherms exhibit a critical field Bc = 11.5 T marked by a clear point of inflection. A minimal Hamiltonian employing S = 1 (pseudo) spins with only a single energy scale (successfully used to model the behavior of bulk f-electron metamagnets) is shown to provide a good description of the observed linear scaling between T1, T3 and Bc. We further show that a Heisenberg Hamiltonian previously employed by Carretta et al (2013 J. Phys.: Condens. Matter 25 486001) to model this single molecule magnet gives formulas for the angle averaged susceptibilities (in the Ising limit) very similar to those of the minimal model.