- Leonid Sandratskii: First-principles insight into magnetism of pure and hydrogenated U2Ni2Sn
- 18. 3. 2020, 14:10
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
Recent experiment [1] on single crystal of U2Ni2Sn revealed unusual magnetic structure and strong uniaxial magnetic anisotropy. The comparison with earlier experiment on hydrogenated U2Ni2Sn [2] has shown drastic change of the magnetic state. In particular, the uniaxial character of magnetic anisotropy has been, apparently, replaced by the easy-plane anisotropy. The purpose of our first-principles study was to suggest a consistent physical picture explaining on the same footing both the properties of the pure UHS and the processes initiated by hydrogen.
The magnetic structure of the H-free U2Ni2Sn is antiferromagnetic both within the U planes and between the U planes separated by the planes of the Ni and Sn atoms. Our calculations of various magnetic configurations confirmed that the experimental double-antiferromagnetic structure has the lowest energy. We discuss the origin of this phenomena from two different viewpoints: (i) analysis of the electronic density of states and (ii) evaluation of the interatomic exchange parameters. Unexpectedly, only one of the interatomic exchange parameters appeared to be antiferromagnetic competing with several ferromagnetic exchange interactions. We explain how such a competition can lead to the coexistence of the in-plane and out-of-plane antiferromagnetism.
The drastic change of the character of the magnetic anisotropy rises the question about continuous vs. discontinuous transformation between two magnetic states. Our calculations show however that hydrogenation makes both competing magnetic structures unstable leading to the stabilization of intermediate states. We discuss the role of the Dzyaloshinskii-Moriya interaction in the processes that were first supposed to be governed by the magnetic anisotropy only.
[1] S. Maskova, A. V. Andreev, Y. Skourski, S. Yasin, D. I. Gorbunov, S. Zherlitsyn, H. Nakotte, K. Kothapalli,
F. Nasreen, C. Cupp, H. B. Cao, A. Kolomiets, and L. Havela, Phys. Rev. B 99, 064415 (2019).
[2] K. Miliyanchuk, L. Havela, L. C. J. Pereira, A. P. Goncalves, and K. Prokes, J. Magn. Magn. Mater.
310, 945 (2007).