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Title: Interplay of local moment and itinerant magnetism in cobalt-based Heusler ferromagnets: Co 2 TiSi ,   Co 2 MnSi and Co 2 FeSi

Journal Article · · Physical Review B

Heusler ferromagnets based on Co are important materials for spintronics. This is due to the exceptional combinations of high Curie temperature and strong spin polarization, including half-metallicity, found in some of these. In this study, we investigate the full Heusler compounds, Co 2 TiSi , Co 2 MnSi , and Co 2 FeSi using first principles calculations. Co 2 TiSi and Co 2 MnSi are half metals, while Co 2 FeSi is not. The trends in the Curie temperatures are reproduced by the calculated spin wave dispersions. Remarkably, Co 2 TiSi is a very itinerant magnet but Co 2 FeSi and Co 2 MnSi show local moment behavior regarding the Fe and Mn, while retaining the itinerancy of the Co magnetism. These materials can therefore be described as itinerant systems with embedded local moment atoms. This provides an explanation for their exceptional behavior. We show that our results do not support the half-metallic character proposed for Co 2 FeSi , but they are consistent with a higher Curie temperature relative to the Mn compound. The density of states and transport spin polarizations Co 2 FeSi have opposite signs. Importantly, although there is a large minority spin density of states at the Fermi level, leading to a low density of states spin polarization, we find a very strong transport spin polarization in Co 2 FeSi . This, combined with the large moment, cubic structure, and high Curie temperature supports the further investigation of Co 2 FeSi for spintronic applications that make use of the transport spin polarization.

Research Organization:
Univ. of Missouri, Columbia, MO (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Grant/Contract Number:
SC0019114
OSTI ID:
1592687
Journal Information:
Physical Review B, Vol. 101, Issue 1; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 8 works
Citation information provided by
Web of Science

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