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SbTe
Shamoto, Shinichi; Yamada, Noboru*; Matsunaga, Toshiyuki*; Proffen, T.*; Richardson, J. W.*; Chung, J.-H.*; Egami, Takeshi*
Applied Physics Letters, 86(8), p.081904_1 - 081904_3, 2005/02
Times Cited Count：51 Percentile：82.63(Physics, Applied)Local structure of NaCl-type crystalline GeSbTe has been studied by the atomic pair distribution function analysis of pulsed neutron powder diffraction data. We have found the large displacement of germanium atoms in this crystalline phase. Usually, such a large lattice distortion has disadvantage for the electric conductivity. The electronic band structure, however, implies that this significant distortion in addition to the lattice defect at Na site reduces only thermal conductivity, while the highly ordered tellurium atoms at Cl site keep high electric conductivity.
studied by neutron diffractionChung, J.-H.*; Proffen, T.*; Shamoto, Shinichi; Ghorayeb, A. M.*; Croguennec, L.*; Tian, W.*; Sales, B. C.*; Jin, R.*; Mandrus, D.*; Egami, Takeshi*
Physical Review B, 71(6), p.064410_1 - 064410_11, 2005/02
Times Cited Count：88 Percentile：91.27(Materials Science, Multidisciplinary)LiNiO (S=1/2) forms a triangular lattice with the possible magnetic frustration, but the exact state of spin correlation has not yet been known. While there is no signature of long-range Jahn-Teller distortion, local JT distortion has been suspected. We have performed neutron diffraction and atomic pair-density function analyses up to unprecedented large distances to discover a number of unusual features, such as anomalous peak broadening, local JT distortion, sharp oxygen-oxygen distance correlations, and inverted temperature dependence of medium range correlation. These observations are best explained by local orbital ordering of Ni
ions into three sublattices. This orbital ordering, however, cannot develop into long-range order because of the strain field it generates, and domains of about 10 nm in size are formed. Domains are susceptible to random pinning by impurities ssite disorderd resulting in the loss of structural long-range order. We suggest that this local orbital ordering is the basis for the complex magnetic properties observed in this compound.
