which encapsulates the Orbach (10 -A e -U eff /T , τ 0 = 10 -A ), Raman (10 R T n , C = 10 R ) and quantum tunneling of magnetisation (τ QTM = 10 Q ) contributions to the overall relaxation rate. The resultant fit is given in Fig. and show good agreement between the fitted model and data. . The waveform (red) and AC data (black) are fitted to Eq. 10, with each contribution represented as a dotted line. Fitted parameters are given in Table .