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arXiv · 1412.1676

Barlowite: A Spin-1/2 Antiferromagnet with a Geometrically Perfect Kagome Motif

Tian-Heng Han·John Singleton·John A. Schlueter
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Abstract

We present thermodynamic studies of a new spin-1/2 antiferromagnet containing undistorted kagome lattices---barlowite Cu$_{4}$(OH)$_{6}$FBr. Magnetic susceptibility gives $θ_{CW}$ = $-$136 K, while long-range order does not happen until $T_{N}$ = 15 K with a weak ferromagnetic moment $μ$ $<$ 0.1$μ_{B}$/Cu. A 60 T magnetic field induces a moment less than 0.5$μ_{B}$/Cu at $T$ = 0.6 K. Specific-heat measurements have observed multiple phase transitions at $T \ll$ $\mid$$θ_{CW}$$\mid$. The magnetic entropy of these transitions is merely 18% of $k_{B}$ln2 per Cu spin. These observations suggest that nontrivial spin textures are realized in barlowite with magnetic frustration. Comparing with the leading spin-liquid candidate herbertsmithite, the superior interkagome environment of barlowite sheds light on new spin-liquid compounds with minimum disorder. The robust perfect geometry of the kagome lattice makes charge doping promising.

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Tian-Heng Han, John Singleton, John A. Schlueter. 2014-12-04. Barlowite: A Spin-1/2 Antiferromagnet with a Geometrically Perfect Kagome Motif. https://doi.org/10.1103/physrevlett.113.227203

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