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Transport properties of single-crystalline Cu x Ti Se 2 ( 0.015 ⩽ x</…

2007; American Physical Society; Volume: 76; Issue: 2 Linguagem: Inglês

10.1103/physrevb.76.024513

1550-235X

Gang Wu, Hui Yang, Li Zhao, X. G. Luo, Tao Wu, Guoyu Wang, X. H. Chen,

Iron-based superconductors research

Transport properties are systematically studied for single crystals of ${\mathrm{Cu}}_{x}\mathrm{Ti}{\mathrm{Se}}_{2}$ $(0.015\ensuremath{\leqslant}x\ensuremath{\leqslant}0.110)$. Both the in-plane and out-of-plane resistivity show a wide peak due to charge density waves (CDWs) for single crystals with $x\ensuremath{\leqslant}0.025$. After the CDW state is completely suppressed around $x=0.055$, the superconductivity is apparently enhanced by Cu doping. No superconducting transition is observed above $1.8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for ${\mathrm{Cu}}_{0.11}\mathrm{Ti}{\mathrm{Se}}_{2}$. The anisotropy in the resistivity increases with increasing Cu content, and is nearly $T$ independent. The CDW state has a strong effect on the Hall coefficient and thermopower. Large thermopower, comparable to that of the triangular lattice ${\mathrm{Na}}_{x}\mathrm{Co}{\mathrm{O}}_{2}$, is observed in ${\mathrm{Cu}}_{x}\mathrm{Ti}{\mathrm{Se}}_{2}$. Intercalation of Cu induces a negative magnetoresistance due to the interaction between conducting carriers and localized magnetic moments.