High-field magnetic ground state in S = 1/2 kagome lattice antiferromagnet ZnCu[subscript 3](OH)[subscript 6]Cl[subscript 2<]

Abstract

Herbertsmithite ZnCu[subscript 3](OH)[subscript 6]Cl[subscript 2] is a kagome lattice antiferromagnet with spin-1/2 and has been demonstrated to be a likely candidate of spin liquid by a number of recent experiments. The high-field magnetization of the kagome lattice is complicated due to the presence of a few percent of extra Cu impurities sitting on the interlayer metallic sites. To determine the magnetic ground state of the kagome lattice, we measured the magnetization of a single crystalline ZnCu[subscript 3](OH)[subscript 6]Cl[subscript 2] using torque magnetometry down to the base temperatures 20 mK in intense magnetic field as high as 31 T. The high-field intrinsic magnetization from the kagome lattice turns out to be linear with magnetic field, and the magnetic susceptibility is independent of temperature at 20 mK ≤ T ≤ 5 K. Moreover, below 2 K, several field-induced anomalies are observed in between 7 T and 15 T.