title: Giant phonon softening and enhancement of superconductivity by phosphorus doping of BaNi2As2.
abstract: The effects of phosphorus doping on the structural and superconducting phase transitions of BaNi2(As(1-x)P(x))2 were studied. The specific heat, resistivity, and magnetic susceptibility were measured. The results revealed an abrupt increase in the superconducting transition temperature (T(c)) from 0.6 K in the triclinic phase (space group P1¯) with less phosphorus (x≤0.067) to 3.3 K in the tetragonal phase (space group I4/mmm) with more phosphorus (x≥0.067). Our data analysis suggests that a doping-induced softening related to an in-plane Ni and As(P) phonon mode is responsible for the enhanced superconductivity in the tetragonal phase.
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan. kudo@science.okayama-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Kudo
authors.forename: M
authors.initials: M
authors.lastname: Takasuga
authors.forename: Y
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Z
authors.initials: Z
authors.lastname: Hiroi
authors.forename: M
authors.initials: M
authors.lastname: Nohara