Searching for Quantum Spin Liquids in S = 1/2 Kagome Systems: synthetic challenges and recent advances

Ross Colman (UCL Chemistry, UK)

The search for the Resonating Valence Bond (RVB) state is a cornerstone of condensed matter physics. It was proposed by Anderson over two decades ago to explain the transition to unconventional superconductivity seen in the high Tc cuprates [1]. Geometric frustration of the magnetic lattice, coupled with a quantum nature of the S = 1 2 spin state is thought to be the key to the observation of the RVB state and a quantum kagome antiferromagnet is considered the most promising model system. Introduction of Herbertsmithite to the experimental research into the area. It was soon realised that all of the Herbertsmithite samples contained signibetween plane magnetic defects. An anti-symmetric component to the exchange in Herbertsmithite [3], known as a Dzyaloshinski-Moriya interaction, is predicted to stabilise a Néel ground state but despite these features a dynamic ground state is still observed down to the lowest temperatures. In this talk I will discuss three new S = 1 2 kagome materials: Kapellasite, ®-Cu3Zn(OH)6Cl2 [4]; Haydeeite, ®-Cu3Mg(OH)6Cl2; and Mg-Herbertsmithite, °-Cu3Zn(OH)6Cl2. Magnetisation measurements show Kapellasite to have no magnetic order down to the lowest temperatures whilst Haydeeite and Mg-Herbertsmithite undergo magnetic transitions. Considering the structural ditheir properties, and the ability to probe a range of materials is necessary for separating the inherent material properties from the intrinsic signature of a spin-liquid ground state. References [1] Anderson, P. W.; Baskaran, G.; Zou, Z.; Hsu, T. Phys. Rev. Lett. 1987, 58, 2790. [2] Shores, M. P. et. al. J. Am. Chem. Soc. 2005, 127, 13462 [3] Zorko, A. et. al. Phys. Rev. Lett. 2008, 101, 026405 [4] Colman, R.; Ritter, C.; Wills, A. S. Chem. Mater. 2008, 20, 6897

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