Level crossings and zero-field splitting in the{Cr8}-cubane spin cluster studied using inelastic neutron scattering and magnetization

Abstract

Inelastic neutron scattering (INS) in variable magnetic field and high-field magnetizationmeasurements in the millikelvin temperature range were performed to gain insight into the low-energymagnetic excitation spectrum and the field-induced level crossings in the molecular spin cluster{Cr8}-cubane. These complementary techniques provide consistent estimates of the lowestlevel-crossing field. The overall features of the experimental data are explained using anisotropic Heisenberg model, based on three distinct exchange interactions linking the eightCrIII paramagneticcenters (spins s = 3/2), that is supplemented with a relatively large molecular magnetic anisotropy term for the lowestS = 1 multiplet. It is noted that the existence of the anisotropy is clearly evident from themagnetic field dependence of the excitations in the INS measurements, while themagnetization measurements are not sensitive to its effects.