Selective doping Barlowite for quantum spin liquid: a first-principles study

الأصل · EN

Barlowite Cu₄(OH)₆FBr is a newly found mineral containing Cu²⁺ kagome planes. Despite similarities in many aspects to Herbertsmithite Cu₃Zn(OH)₆Cl₂, the well-known quantum spin liquid (QSL) candidate, intrinsic Barlowite turns out not to be a QSL, possibly due to the presence of Cu²⁺ ions in between kagome planes that induce interkagome magnetic interaction [PRL, 113, 227203 (2014)]. Using first-principles calculation, we systematically study the feasibility of selective substitution of the interkagome Cu ions with isovalent nonmagnetic ions. Unlike previous speculation of using larger dopants, such as Cd²⁺ and Ca²⁺, we identify the most ideal stoichiometric doping elements to be Mg and Zn in forming Cu₃Mg(OH)₆FBr and Cu₃Zn(OH)₆FBr with the highest site selectivity and smallest lattice distortion. The equilibirium anti-site disorder in Mg/Zn- doped Barlowite is estimated to be one order of magnitude lower than that in Herbertsmithite. The single-electron band structure and orbital component analysis show that the proposed selective doping effectively mitigates the difference between Barlowite and Herbertsmithite.