NMR in magnetite below and around the Verwey transition

NMR on Fe-57 nuclei was measured in two single crystals of magnetite between 4.2 and 135 K (temperature of the Verwey transition T-V = 121.5 and 123.9 K). We were able to register all lines detected at 4.2 K also at higher temperatures up to T-V. The spectra are compatible with the space group Cc, which predicts 8 and 16 lines for iron on tetrahedral (A) and octahedral (B) sites, respectively. One of the Fe(A) lines is doubly degenerate for all Te TV, which restricts the possible models of the Fe2+ and Fe3+ ordering on the B sites. Above T-V no remnant of the low-temperature spectrum was detected. At 4.2 K the NMR spin-spin and spin-lattice relaxation times were determined.