A Mossbauer study of slow spin relaxation of paramagnetic Fe2+in MgCO3

Abstract

The Mossbauer spectrum of dilute 57Fe2+in MgCO3 shows a well resolved magnetic hyperfine pattern at 4.2K due to a very slow rate of electronic spin relaxation. Above 60K only pure quadrupole splitting is obtained as a result of very fast spin-lattice relaxation rate. The spin-lattice relaxation behaviour of Fe2+:MgCO3 is very similar to that of Fe2+:ZnCO3, which shows that the slow spin relaxation of Fe2+ is a consequence of its trigonal site symmetry in a carbonate lattice.