Elisa M. Wheeler

Spin and orbital order in the vanadium spinel MgV2O4

octahedra and a low temperature space group (I4m2) that maintains the mirrorplane symmetry. The magnetic structure that develops below 42K consists of antiferromagneticchains with a strongly reduced moment while inelastic neutron scattering reveals one-dimensionalbehavior and a single band of excitations. The implications of these results are discussed in terms ofvarious orbital ordering scenarios. We conclude that although spin-orbit coupling must be signi cantto maintain the mirror plane symmetry, the trigonal distortion is large enough to mix the 3d levelsleading to a wave function of mixed real and complex orbitals.

Physical realization of a quantum spin liquid based on a complex frustration mechanism

A detailed and systematic study of Ca10Cr7O28 reveals all the hallmarks of spin-liquid behaviour, in spite of the compound’s unusually complex structure.

Multiple lattice instabilities resolved by magnetic-field and disorder sensitivities inMgV2O4

Tadataka Watanabe, Takashi Ishikawa, Shigeo Hara, A. T. M. Nazmul Islam, Elisa M. Wheeler, and Bella Lake Department of Physics, College of Science and Technology (CST), Nihon University, Chiyoda, Tokyo 101-8308, Japan Department of Physics, Chuo University, Bunkyo, Tokyo 101-8324, Japan and Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany (Dated: May 13, 2014)

Ultrasound velocity measurements in orbital-degenerate frustrated spinel MgV2O4

Ultrasound velocity measurements of the orbital-degenerate frustrated spinel MgV2O4 are performed in the disorder-free high-purity single crystal which exhibits successive structural and antiferromagnetic phase transitions, and in the disorder-introduced single crystal which exhibits spin-glass-like behavior. The measurements reveal coexisting two types of anomalous temperature dependence of the elastic moduli in the cubic paramagnetic phase: Curie-type softening with decreasing temperature, and softening with a characteristic minimum with decreasing temperature. These elastic anomalies should respectively originate from the coexisting orbital fluctuations and spin-cluster excitations.