Copper Doping of BaNi$_{2}$As$_{2}$: Giant Phonon Softening and Superconductivity Enhancement

Kazutaka Kudo; Masaya Takasuga; Minoru Nohara

paper

Copper Doping of BaNi $_{2}$ As $_{2}$ : Giant Phonon Softening and Superconductivity Enhancement

arXiv:1704.04854

Abstract

The effects of copper doping on the structural and superconducting phase transitions of Ba(Ni $_{1 - x}$ Cu $_{x}$ ) $_{2}$ As $_{2}$ were studied by examining the resistivity, magnetic susceptibility, and specific heat. We found an abrupt increase in the superconducting transition temperature $T_{c}$ from 0.6 K in the triclinic phase with less copper ( $x$ $\leq$ 0.16) to 2.5-3.2 K in the tetragonal phase with more copper ( $x$ $>$ 0.16). The specific-heat data suggested that doping-induced phonon softening was responsible for the enhanced superconductivity in the tetragonal phase. All of these observations exhibited striking similarities to those observed in the phosphorus doping of BaNi $_{2}$ (As $_{1 - x}$ P $_{x}$ ) $_{2}$ [K. Kudo et al., Phys. Rev. Lett. 109, 097002 (2012).], which markedly contrast the behavior of phosphorus and copper doping of the iron-based superconductor BaFe $_{2}$ As $_{2}$ .

arXiv comment5 pages, 4 figures

Copper Doping of BaNi2​As2​: Giant Phonon Softening and Superconductivity Enhancement

Abstract

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Copper Doping of BaNi $_{2}$ As $_{2}$ : Giant Phonon Softening and Superconductivity Enhancement