C. de la Cruz

First-order magnetic and structural phase transitions in Fe1+ySexTe1-x

We use bulk magnetic susceptibility, electronic specific heat, and neutron scattering to study structural and magnetic phase transitions in Fe1+ySexTe1-x. Fe1.068Te exhibits a first-order phase transition near 67 K with a tetragonal-to-monoclinic structural transition and simultaneously develops a collinear antiferromagnetic (AF) order responsible for the entropy change across the transition. Systematic studies of the FeSe1-xTex system reveal that the AF structure and lattice distortion in these materials are different from those of FeAs-based pnictides. These results call into question the conclusions of present density-functional calculations, where FeSe1-xTex and FeAs-based pnictides are expected to have similar Fermi surfaces and therefore the same spin-density wave AF order.

Structure and magnetic properties of the pyrochlore iridate Y2Ir2O7

Neutron powder diffraction and inelastic measurements were performed examining the

Magnetic order in the pyrochlore iridates A(2)Ir(2)O(7) (A = Y, Yb)

5d

Magnetic order and the electronic ground state in the pyrochlore iridate Nd2Ir2O7

pyrochlore Y

Spin waves and magnetic exchange interactions in the spin-ladder compound RbFe 2 Se 3

{}_{2}

Spin-lattice coupling in iron-pnictide superconductors

Ir

Candidate Elastic Quantum Critical Point in LaCu6-xAux

{}_{2}

Coupling of structure to magnetic and superconducting orders in quasi-one-dimensional K2Cr3As3

O

Mott localization in a pure stripe antiferromagnet Rb1-δFe1.5-σS2

{}_{7}

LaCu6−xAgx: A promising host of an elastic quantum critical point

. Temperature-dependent measurements were performed between 3.4 K and 290 K, spanning the magnetic transition at 155 K. No sign of any structural or disorder-induced phase transition was observed over the entire temperature range. In addition, no sign of magnetic long-range order was observed to within the sensitivity of the instrumentation. These measurements do not rule out long-range magnetic order, but the neutron-powder-diffraction structural refinements do put an upper bound for the ordered iridium moment of