paper

Effect of Zn doping on the antiferromagnetism in kagome CuZn(OH)FBr

arXiv:1712.06732 · doi:10.1103/PhysRevB.98.155127

Abstract

Barlowite Cu(OH)FBr shows three-dimensional (3D) long-range antiferromagnetism, which is fully suppressed in CuZn(OH)FBr with a kagome quantum spin liquid ground state. Here we report systematic studies on the evolution of magnetism in the CuZn(OH)FBr system as a function of to bridge the two limits of Cu(OH)FBr (=0) and CuZn(OH)FBr (=1). Neutron-diffraction measurements reveal a hexagonal-to-orthorhombic structural change with decreasing temperature in the = 0 sample. While confirming the 3D antiferromagnetic nature of low-temperature magnetism, the magnetic moments on some Cu sites on the kagome planes are found to be vanishingly small, suggesting strong frustration already exists in barlowite. Substitution of interlayer Cu with Zn with gradually increasing completely suppresses the bulk magnetic order at around = 0.4, but leaves a local secondary magnetic order up to with a slight decrease in its transition temperature. The high-temperature magnetic susceptibility and specific heat measurements further suggest that the intrinsic magnetic properties of kagome spin liquid planes may already appear from samples. Our results reveal that the CuZn(OH)FBr may be the long-thought experimental playground for the systematic investigations of the quantum phase transition from a long-range antiferromagnet to a topologically ordered quantum spin liquid.

9 pages, 6 figures

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