paper

Superconductivity, charge- or spin-density wave, and metal-nonmetal transition in BaTi(SbBi)O

arXiv:1211.4548 · doi:10.1103/PhysRevB.87.100502

Abstract

We have performed an isovalent substitution study in a layered titanium oxypnictide system BaTi(SbBi)O (0 0.40) by the measurements of x-ray diffraction, electrical resistivity and magnetic susceptibility. The parent compound BaTiSbO is confirmed to exhibit superconductivity at 1.5 K as well as charge- or spin-density wave (CDW/SDW) ordering below 55 K. With the partial substitution of Sb by Bi, the lattice parameters , and all increase monotonically, indicating negative chemical pressure and lattice distortion on the (super)conducting TiSbO-layers. The Bi doping elevates the superconducting transition temperature to its maximum =3.7 K at 0.17, and then decreases gradually with additional Bi doping. A metal-to-nonmetal transition takes place around =0.3, and superconductivity at 1K exists at the nonmetal side. The CDW/SDW anomaly, in comparison, is rapidly suppressed by the Bi doping, and vanishes for 0.17. The results are discussed in terms of negative chemical pressure and disorder effect.

arXiv comment5 pages, 5 figures. Minor changes were made

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