Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 47: Quantum Magnets, Molecular Magnets and Skyrmions

TT 47.8: Talk

Wednesday, April 3, 2019, 17:00–17:15, H23

Quantum tunneling and large coercivity in Fe-doped Li₃N — Manuel Fix¹, Enrique del Barco², and •Anton Jesche¹ — ¹EP VI, Center for Electronic Correlations and Magnetism, Augsburg University, 86135 Augsburg, Germany — ²Department of Physics, University of Central Florida, Orlando, Florida 32816, USA

The basic magnetic unit in Fe-doped Li₃N is not a cluster or a domain but the magnetic moment of single, isolated Fe ions [1]. This novel model system shows large magnetic anisotropy and allows to study quantum tunneling of the magnetization in a rather simple, inorganic material at liquid helium temperatures.

For small concentrations of roughly 0.1 % Fe, we have found an extreme field-dependence of the magnetic tunneling [2]. Applied longitudinal fields lift the ground-state degeneracy and destroy the tunneling condition. The relaxation time increases from τ ∼ 10⁴ by four orders of magnitude in applied fields of only a few milliTesla, which reveals exceptionally sharp tunneling resonances. In applied transverse magnetic fields, on the other hand, the spin-flip probability increases, which proves the resonant character of this tunneling process. Therefore, it is possible either to freeze the orientation or to promote the flip of a spin-state by tiny applied fields.
A. Jesche et al., Nat. Commun. 5:3333 (2014)
M. Fix, J. H. Atkinson, P. C. Canfield, E. del Barco, A. Jesche, Phys. Rev. Lett. 120, 147202 (2018)