Abstract
Barlowite Cu4(OH)6FBr shows three-dimensional (3D) long-range antiferromagnetism, which is fully suppressed in Cu3Zn(OH)6FBr with a kagome quantum spin liquid ground state. Here we report systematic studies on the evolution of magnetism in the Cu4-xZnx(OH)6FBr system as a function of x to bridge the two limits of Cu4(OH)6FBr(x=0) and Cu3Zn(OH)6FBr(x=1). Neutron-diffraction measurements reveal a hexagonal-to-orthorhombic structural change with decreasing temperature in the x=0 sample. While confirming the 3D antiferromagnetic nature of low-temperature magnetism, the magnetic moments on some Cu2+ sites on the kagome planes are found to be vanishingly small, suggesting strong frustration already exists in barlowite. Substitution of interlayer Cu2+ with Zn2+ with gradually increasing x completely suppresses the bulk magnetic order at around x=0.4 but leaves a local secondary magnetic order up to x∼0.8 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 x>0.3 samples. Our results reveal that the Cu4-xZnx(OH)6FBr 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.
Original language | English |
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Article number | 155127 |
Journal | Physical Review B |
Volume | 98 |
Issue number | 15 |
DOIs | |
State | Published - Oct 16 2018 |
Funding
This work was supported by the National Key R&D Program of China (Grants No. 2016YFA0300502, No. 2017YFA0302900, and No. 2016YFA0300604), the National Natural Science Foundation of China (Grants No. 11874401, No. 11674406, No. 11374346, No. 11774399, No. 11474330, No. 11421092, No. 11574359, and No. 11674370), the Strategic Priority Research Program(B) of the Chinese Academy of Sciences (Grants No. XDB07020300, No. XDB07020000, and No. XDB28000000), the China Academy of Engineering Physics (Grant No. 2015AB03), and the National Thousand-Young Talents Program of China. Research conducted at ORNLs High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.