Field tuning of thermally activated magnetic quantum tunnelling in Mn12-Ac molecules
Facultat de Física, Universitat de Barcelona - 08028 Barcelona, Spain
2 Instituto de Ciencia de Materiales de Aragón - 50009 Zaragoza, Spain
3 Wilson Center for Research and Technology, Xerox Corporation, Webster NY 14580, USA
Accepted: 17 June 1996
Zero-field–cooled magnetization, magnetic relaxation, and a.c. susceptibility measurements have been performed on a -Ac oriented powdered sample as a function of temperature, field, and orientation. Magnetization jumps and susceptibility peaks have been observed about magnetic-field values , where 5 kG. These anomalies are due to the existence of relaxation rate maxima near Bn. From these experimental results we infer the existence of resonant spin tunnelling between degenerate excited levels of opposite spin orientation.
PACS: 75.30.Cr – Saturation moments and magnetic susceptibilities / 75.50.Tt – Fine-particle systems / 75.30.Gw – Magnetic anisotropy
© EDP Sciences, 1996