Charge Order without Spin Order in the Layered Frustrated Magnet κ-(BEDT-TTF)2Hg(SCN)2Cl

ORAL

Abstract

There are several quasi two-dimensional materials which do not order magnetically, including a number of geometrically frustrated organic charge transfer salts. To investigate the interplay between charge order (which may affect the frustration) and magnetic order, we use 1H NMR spectroscopy to examine the magnetic properties of κ-(BEDT-TTF)2Hg(SCN)2Cl, which exhibits a first-order metal-insulator transition to a charge ordered state at TCO = 30K. The high-temperature metallic phase exhibits Fermi-liquid behavior with constant (T1T)−1, while the spin-lattice relaxation rate is subject to an abrupt enhancement at TCO and shows a standard paramagnetic response down to 2 K, below which the relaxation rates decrease as 1/T1 ~ T2. The smooth temperature dependence of T1 and the absence of changes in the NMR spectra rule out magnetic order down to 25 mK suggesting decoupling of the spin and charge degrees of freedom, while the CO is expecetd to reduce the frustration. These observations are discussed in the context of the ground state without magnetic order. Ongoing field-dependent measurements may elucidate whether the magnetic interactions are subject to 1D physics.

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Presenters

  • Teresa Le

    University of California, Los Angeles

Authors

  • Teresa Le

    University of California, Los Angeles

  • Andrej Pustogow

    Department of Physics and Astronomy, University of California, Los Angeles, University of California, Los Angeles, 1. Physikalisches Institut, Universität Stuttgart

  • Hsin-Hua Wang

    University of California, Los Angeles

  • Yongkang Luo

    Department of Physics and Astronomy, University of California, Los Angeles, University of California, Los Angeles

  • Elena Gati

    Ames Laboratory/Iowa State University, Institute of Physics, Goethe-University Frankfurt

  • Michael Lang

    Institute of Physics, Goethe-University Frankfurt

  • Stuart E Brown

    Univ of California - Los Angeles, Department of Physics and Astronomy, University of California, Los Angeles, University of California, Los Angeles