1302.5369 (H. B. Cao et al.)

Origin of structural transition in IrTe_2 studied by single crystal
neutron and X-ray diffraction    [PDF]

H. B. Cao, B. C. Chakoumakos, J. -Q. Yan, H. D. Zhou, R. Custelcean, D. Mandrus

We combined single crystal neutron and X-ray diffraction to study the ground state (GS) structure of IrTe_2. A structural modulation was observed by both neutrons and X-rays with a wave vector of k =(1/5, 0, 1/5) below T_s=285 K accompanied by a trigonal to monoclinic lattice distortion. The GS structure lattice was determined to be am=6.642(4)A, bm=3.965(3)A, cm=5.434(3)A, alpha_m=90.0(2), beta_m=90.0(2), and gamma_m=90.1(2) at 5 K. Shortening two of the three nearest Ir-Ir bonds below T_s drives the distortion of the IrTe_6 octahedra. The complete GS structure was optimized by matching with the observed X-ray and neutron patterns. Ir 5d orbital order is likely the origin of the structural transition.

View original: http://arxiv.org/abs/1302.5369