title: Emerging superconductivity hidden beneath charge-transfer insulators.
abstract: In many of today's most interesting materials, strong interactions prevail upon the magnetic moments, the electrons, and the crystal lattice, forming strong links between these different aspects of the system. Particularly, in two-dimensional cuprates, where copper is either five- or six-fold coordinated, superconductivity is commonly induced by chemical doping which is deemed to be mandatory by destruction of long-range antiferromagnetic order of 3d(9) Cu(2+) moments. Here we show that superconductivity can be induced in Pr2CuO4, where copper is four-fold coordinated. We induced this novel quantum state of Pr2CuO4 by realizing pristine square-planar coordinated copper in the copper-oxygen planes, thus, resulting in critical superconducting temperatures even higher than by chemical doping. Our results demonstrate new degrees of freedom, i.e., coordination of copper, for the manipulation of magnetic and superconducting order parameters in quantum materials.
authors.affiliation: NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan. yoshiharu.k@lab.ntt.co.jp
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Krockenberger
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Irie
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsumoto
authors.forename: Keitaro
authors.initials: K
authors.lastname: Yamagami
authors.forename: Masaya
authors.initials: M
authors.lastname: Mitsuhashi
authors.forename: Akio
authors.initials: A
authors.lastname: Tsukada
authors.forename: Michio
authors.initials: M
authors.lastname: Naito
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamamoto