Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Magnetism Poster A
MA 15.21: Poster
Dienstag, 2. April 2019, 10:00–13:00, Poster E
High-field ESR study of giant single ion magnetic anisotropy in Li2(Li1−xCox)N — •Y. Krupskaya1, T. Ballé2, L. Puntigam2, A. Jesche2, Z. Zangeneh1, L. Xu1, L. Hozoi1, B. Büchner1, and V. Kataev1 — 1IFW Dresden, Germany — 2Augsburg University, Germany
Recently an extreme, uniaxial magnetic anisotropy and large magnetic hysteresis were observed in the Li2(Li1−xFex)N compound [1]. Static magnetization measurements revealed a coercivity field of over 11 T at T = 2 K and allowed to estimate a magnetic anisotropy field of 220 T. Substitution of Fe with other transition metal ions allows to alternate the sign of the magnetic anisotropy, resulting in easy plane - easy axis - easy plane - easy axis configurations when progressing along the Mn - Fe - Co - Ni series [2]. We have studied a Li2(Li1−xCox)N single crystal with x = 0.01 by means of high-field multi-frequency electron spin resonance spectroscopy (HF-ESR), which is known as an efficient tool to directly measure the magnetic anisotropy energy in single-molecule magnets. The measurements have been performed in magnetic fields up to 16 T and excitation frequencies up to 750 GHz. HF-ESR results clearly evidence easy-plane magnetic behavior and enable to determine a Co-ion magnetic anisotropy gap of 972 GHz, in agreement with ab initio quantum chemical calculations. Different from the case of the Li2(Li1−xFex)N compound, where first-order spin-orbit coupling plays the main role, the magnetic anisotropy of Co ions in Li2(Li1−xCox)N is related to second-order effects. [1] A. Jesche et al. Nat. Commun. 5, 3333 (2014); [2] A. Jesche et al. Phys. Rev. B 91, 180403(R) (2015).