Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 9: Cooperative phenomena: Spin structures and magnetic phase transitions

MA 9.1: Talk

Monday, April 1, 2019, 15:00–15:15, H53

Linearly coordinated Ni in the two-dimensional quantum magnet K₂NiO₂ — Tanita J. Ballé, •Laurin Brunner, Alexander A. Tsirlin, and Anton Jesche — EP VI, Center for Electronic Correlations and Magnetism, Augsburg University, 86135 Augsburg, Germany

A huge magnetic anisotropy and the highest known coercivity field of more than 11 T are observed in Li₂[Li_1−xFe_x]N, one of the scarce rare-earth free hard magnets. In this compound an unquenched orbital moment is manifested, enabled by the perfect linear, twofold coordination of iron between nitrogen, that gives rise to these properties [1]. In order to investigate the limits in exploiting this geometrical motive to achieve stable magnetic moments, we investigated similar compounds [2]. We will discuss the magnetic properties of a new member of this series: K₂NiO₂ that contains nickel in linear, twofold coordination between oxygen.

Field- and temperature dependent measurements of the Magnetization were performed, complemented by heat capacity data. Density functional theory revealed moderately enhanced orbital contributions to the magnetic moment of nickel. The magnetic susceptibility was calculated in a Heisenberg model and is in reasonable agreement with experiment.

[1] A. Jesche et al. Nat. Commun. 5:3333. doi: 10.1038/ncomms4333 (2014)

[2] P. Höhn, TJB et al. Inorganics 4, 42 (2016)