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

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  =  χ ₁ B  +  χ ₃ B ³ we extract the linear susceptibility χ ₁ and the leading order nonlinear susceptibility χ ₃. We find that χ ₁ exhibits a peak at a temperature of T ₁  =  10.4 K with χ ₃ also exhibiting a peak but at a reduced temperature T ₃  =  5 K. At the lowest temperatures the isotherms exhibit a critical field B _c  =  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 T ₁, T ₃ and B _c. 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.