Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 3: Quantum Magnets and Molecular Magnets (joint session TT/MA)
MA 3.2: Vortrag
Montag, 12. März 2018, 09:45–10:00, H 3010
Extreme field-sensitivity of the magnetic tunnelling in Fe-doped Li3N — •Manuel Fix1, James H. Atkinson2, Paul C. Canfield3,4, Enrique del Barco2, and Anton Jesche1 — 1EP VI, EKM, University of Augsburg, D-86159, Germany — 2Department of Physics, UCF, Orlando FL 32816, USA — 3The Ames Laboratory, ISU, Ames, Iowa 50011, USA — 4Department of Physics and Astronomy, ISU, Ames, Iowa 50011, USA
The magnetic properties of dilute Li2(Li1−xFex)N with x ∼ 0.001 are dominated by the spin of single, isolated Fe atoms [1]. Below T = 10 K the spin-relaxation times become temperature-independent, indicating a crossover from thermal excitations to the quantum tunnelling regime.
The spin-flip probability increases tremendously in transverse magnetic fields, proving the resonant character of this tunnelling process. Upon application of longitudinal fields, on the other hand, the ground-state degeneracy is lifted and the tunnelling condition destroyed. We show time dependent magnetization measurements performed on single crystals in various longitudinal magnetic fields at temperatures T = 2−16 K. An increase of the relaxation time by four orders of magnitude in applied fields of only a few milliTesla reveals exceptionally sharp tunnelling resonances. This strong field dependence of the spin reversal could be employed to create stable (µ0 Hz = 3 mT) but switchable (Hz = 0) magnetic ’quantum bits’ at elevated temperatures.
A. Jesche et al., Nature Comm. 5:3333 (2014)