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arXiv:2204.09695 · Physical review. B./Physical review. B

Ab initio guided minimal model for the “Kitaev” material BaCo2 ( AsO4)2 : Importance of direct hopping, third-neighbor exchange, and quantum fluctuations

P. A. Maksimov, Alexey V. Ushakov, Z. V. Pchelkina, Ying Li, Stephen M. Winter, Sergey V Streltsov

Published Oct 31, 2022• 54 citations
arXivHTMLPDF

Abstract

By considering two ab initio-based complementary approaches, we analyze the electronic structure and extract effective spin models of ${\mathrm{BaCo}}_{2}{({\mathrm{AsO}}_{4})}_{2}$, a honeycomb material which has been proposed as a candidate for Kitaev physics. Both methods show that the dominant direct hopping makes the bond-dependent Kitaev term negligible, diverting the material away from the sought-after spin-liquid regime. As a result, we present a simple three-parameter exchange model to describe the interactions of the lowest doublet of the honeycomb cobaltate ${\mathrm{BaCo}}_{2}{({\mathrm{AsO}}_{4})}_{2}$. Remarkably, it is the third-neighbor interactions, both isotropic and anisotropic, that are responsible for the standout double-zigzag ground state of ${\mathrm{BaCo}}_{2}{({\mathrm{AsO}}_{4})}_{2}$, stabilized by quantum fluctuations. A significantly large third-nearest-neighbor hopping, observed ab initio, supports the importance of the third-neighbor interactions in the stabilization of the unique ground state of ${\mathrm{BaCo}}_{2}{({\mathrm{AsO}}_{4})}_{2}$.

DOI
10.1103/physrevb.106.165131

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Can we realize Kitaev quantum spin liquids in the Jeff=1/2J_\text{eff}=1/2Jeff​=1/2 honeycomb cobaltates?
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