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arXiv · 1810.01050

Electron doping of proposed quantum spin liquid kagomé Zn-Cu hydroxyl-halides produces localized states in the band gap

Qihang Liu·Qiushi Yao·Z. A. Kelly·C. M. Pasco·T. M. McQueen·S. Lany·Alex Zunger
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Abstract

Carrier doping of quantum spin liquids is a long-proposed route to the emergence of high-temperature superconductivity. Electrochemical intercalation in kagome hydroxyl-halide materials shows that samples remain insulating across a wide range of electron counts. Here we demonstrate through first-principles density functional calculations corrected for self-interaction the mechanism by which electrons remain localized in various Zn-Cu hydroxyl-halides, independently of the chemical identity of the dopant - the formation of polaronic states with attendant lattice displacements and a dramatic narrowing of bandwidth upon electron addition. The same theoretical method applied to electron doping in cuprate Nd2CuO4 correctly produces a metallic state when the initially formed polaron dissolves into an extended state. Our general findings explain the insulating behavior in a wide range of doped quantum magnets and demonstrate that new quantum spin liquid host materials are needed to realize metallicity borne of a spin liquid.

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Qihang Liu, Qiushi Yao, Z. A. Kelly, C. M. Pasco, T. M. McQueen, S. Lany, Alex Zunger. 2018-10-02. Electron doping of proposed quantum spin liquid kagomé Zn-Cu hydroxyl-halides produces localized states in the band gap. https://doi.org/10.1103/physrevlett.121.186402

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