Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Deciphering Structural and Magnetic Disorder in the Chiral Skyrmion Host Materials CoxZn^y^Mnz (x + Y + z = 20)

Published

Author(s)

Joshua D. Bocarsly, Colin A Heikes, Craig Brown, Stephen D. Wilson, Ram Seshadri

Abstract

CoxZnyMnz (x+y+z = 20) compounds crystallizing in the chiral β-Mn crystal structure are known to host skyrmion spin textures even at elevated temperatures. As in other chiral cubic skyrmion hosts, skyrmion lattices in these materials are found at equilibrium in a small pocket just below the magnetic Curie temperature. Remarkably, CoxZnyMnz compounds have also been found to host metastable non-equlibrium skyrmion lattices in a broad temperature and field range, including down to zero-field and low temperature. This behavior is believed to be related to disorder present in the materials. Here, we use neutron and neutron and synchrotron diffraction, density functional theory calculations, and DC and AC magnetic measurements, to characterize the atomic and magnetic disorder in these materials. We demonstrate that Co has a strong site-preference for the diamondoid 8c site in the crystal structure, while Mn tends to share the geometrically frustrated 12d site with Zn, due to its ability to develop a large local moment on that site. This magnetism-driven site specificity leads to distinct magnetic behavior for the Co-rich 8c sublattice and the Mn on the 12d sublattice. The Co-rich sublattic orders at high temperatures (compositionally tunable between 100K to 470K) with a moment around 1 {mu]B/atom and maintains this order to low temperature. The Mn-rich sublattice holds larger moments (about 3{muB}) which remain fluctuating below the Co moment ordering temperature. At lower temperature, the fluctuating Mn moments freeze into a reentrant disordered cluster-glass state with no net moment, while the Co moments maintain order. This two-sublattice behavior allows for the observed coexistence of strong magnetic disorder and ordered magnetic states such as helimagnetims and skyrmion lattices.
Citation
Physical Review Materials
Volume
3
Issue
1

Keywords

skyrmions, neutron diffraction, magnetism
Created January 1, 2019, Updated January 15, 2020