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Article Dans Une Revue Journal of Physics: Condensed Matter Année : 2023

Minority-spin conducting states in Fe substituted pyrite CoS$_2$

Anustup Mukherjee
Alaska Subedi

Résumé

There has been a longstanding debate whether the pyrite CoS$_2$ or its alloys with FeS$_2$ are half metallic. We argue using first principles calculations that there is a finite occupation of minority-spin states at the Fermi level throughout the series Co$_{1-x}$Fe$_x$S$_2$. Although the exchange-correlation functional influences the specifics of the electronic structure, we observe a similar trend with increasing Fe concentration in both LDA and GGA calculations. Specifically, even as band filling is decreased through Fe substitution, the lowest-lying conduction band in the minority-spin channel broadens such that these states keep getting lowered relative to the Fermi level, which is contrary to the expectations from a rigid band picture. Furthermore, the exchange splitting decreases as more Co atoms are replaced by Fe, and this again brings the minority-spin states closer to the Fermi level. These two mechanisms, in conjunction with the experimental observation that minority-spin bands cross the Fermi level in stoichiometric CoS$_2$, indicate that minority-spin charge carriers will always be present in Co$_{1-x}$Fe$_x$S$_2$.
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Dates et versions

hal-04307902 , version 1 (26-11-2023)

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Anustup Mukherjee, Alaska Subedi. Minority-spin conducting states in Fe substituted pyrite CoS$_2$. Journal of Physics: Condensed Matter, 2023, 36 (2), pp.025501. ⟨10.1088/1361-648X/acfde9⟩. ⟨hal-04307902⟩
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