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Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy


Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy

S. Gómez-Coca, A. Urtizbarea, E. Cremades, P. J. Alonso, A. Camón, E. Ruiz, F. Luis

Nature Commun., 5 (2014) 4300.

2014-line2-a-250x200

 

Quantitative first-principles calculations on the Kramers CoII ion in the [Co(acac)2(H2O)2] complex show that the slow magnetic relaxation in this and similar systems is a general consequence of time-reversal symmetry that hinders direct spin-phonon processes. This conclusion applies regardless of the sign of the zero-field splitting parameters associated to the two forms of magnetic anisotropy, easy axis and easy field magnetization. The hyperfine interaction between electronic and nuclear spins opens paths for magnetic relaxation that would otherwise be forbidden by time reversal symmetry and uncovers a promising strategy for the design and achievement of atom-size magnetic memories.