Chiral Magnetism and Higherature Skyrmions in B20-Ordered Co-Si

Balamurugan Balasubramanian, Priyanka Manchanda, Rabindra Pahari, Zhen Chen, Wenyong Zhang, Shah R. Valloppilly, Xingzhong Li, Anandakumar Sarella, Lanping Yue, Ahsan Ullah, Pratibha Dev, David A. Muller, Ralph Skomski, George C. Hadjipanayis, David J. Sellmyer

Research output: Contribution to journalArticle

Abstract

Magnets with chiral crystal structures and helical spin structures have recently attracted much attention as potential spin-electronics materials, but their relatively low magnetic-ordering temperatures are a disadvantage. While cobalt has long been recognized as an element that promotes higherature magnetic ordering, most Co-rich alloys are achiral and exhibit collinear rather than helimagnetic order. Crystallographically, the B20-ordered compound CoSi is an exception due to its chiral structure, but it does not exhibit any kind of magnetic order. Here, we use nonequilibrium processing to produce B20-ordered Co1+xSi1-x with a maximum Co solubility of x=0.043. Above a critical excess-Co content (xc=0.028), the alloys are magnetically ordered, and for x=0.043, a critical temperature Tc=328 K is obtained, the highest among all B20-type magnets. The crystal structure of the alloy supports spin spirals caused by Dzyaloshinskii-Moriya interactions, and from magnetic measurements we estimate that the spirals have a periodicity of about 17 nm. Our density-functional calculations explain the combination of high magnetic-ordering temperature and short periodicity in terms of a quantum phase transition where excess-cobalt spins are coupled through the host matrix.

Original languageEnglish (US)
Article number057201
JournalPhysical Review Letters
Volume124
Issue number5
DOIs
StatePublished - Feb 6 2020

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Balasubramanian, B., Manchanda, P., Pahari, R., Chen, Z., Zhang, W., Valloppilly, S. R., Li, X., Sarella, A., Yue, L., Ullah, A., Dev, P., Muller, D. A., Skomski, R., Hadjipanayis, G. C., & Sellmyer, D. J. (2020). Chiral Magnetism and Higherature Skyrmions in B20-Ordered Co-Si. Physical Review Letters, 124(5), [057201]. https://doi.org/10.1103/PhysRevLett.124.057201