High-temperature superconductivity in the BaPb1-xBixO3 systems

Electron-phonon coupling induced pseudogap and the superconducting transition inBa0.67K0.33BiOChainani1, Yokoya2, Shin3 et al. 2001Phys. Rev. B293190View full textAdd to dashboardCite

“…In contrast, the perovskite series Ba 1−x K x BiO 3 (BKBO) is three-dimensional, contains no transition metal ions, has no magnetic order but still exhibits the highest T c known for an oxide other than the cuprates [3]. The superconductivity in the BKBO series was preceded by the analogous BaBi 1−x Pb x O 3 (BPBO) series which shares the same parent BaBiO 3 (BBO) [4]. The role of electron-phonon coupling in the properties of the BKBO and BPBO series originates in the charge density wave (CDW) state of BBO.…”

“…The superconductivity in the BKBO series was preceded by the analogous BaBi 1−x Pb x O 3 (BPBO) series which shares the same parent BaBiO 3 (BBO) [4]. The role of electron-phonon coupling in the properties of the BKBO and BPBO series originates in the charge density wave (CDW) state of BBO.The parent BBO is expected to be a metal from band theory with a half-filled Bi 6s band, but the near perfect nesting possible in BBO causes a three-dimensional CDW gap to open up in the DOS [4,5]. The CDW in BBO is coupled to the breathing mode phonon which is due to the contraction and expansion of oxygen octahedra surrounding neighbouring Bi ions.…”

Analysis of superconductivity in Ba1−xKxBiO3 on the basis of indirect-exchange mediated pairing

“…(2) The transition temperature as a function of doping, Tc(x), in Bal xKxBiO3 shows a highest value for x close to 0.37 [7], while Tc in BaPbx_xBixO3 has its maximum at x = 0.25 [2], well inside the experimental range. Although with (Ba, K) BiO3 experiments do not conclusively demonstrate a maximum of T c in the physical range of x, the expected similarity between the two bismuthates renders a different interpretation of the Tc(x ) curve near x = 0.37 very unlikely.…”

“…15CuO4, and not much lower than Tc = 39 K of its Sr substitute) invalidated the up-to-then prevalent belief that (quasi-) two-dimensional oxide layers containing Cu are a necessary condition for Tc values beyond 30 K. In addition, this high Tc was attained in spite of a very low density-of-states N(Ev) on the order of 10 1 states/(eV, spin.cell), considerably lower than that of A15 alloys such as Nb3Sn with a lower critical temperature (23 K). Interest in the bismuthates had been aroused by the earlier (1975) finding that the related perovskite BaPba-xBixO3 exhibits superconductivity with a maximum Tc of 13 K, at x ~0.25 [2], high among superconductors containing no transition element. Many efforts have since these discoveries been undertaken towards elucidating the pairing mechanism responsible for such unexpected behavior.…”

Magnetization measurements on single crystals of superconducting Ba 0.6 K 0.4 BiO 3

“…(Sleight, Gilson, and Bierstedt, 1975) Subsequent cuprate superconductors command the attention of a great many researchers because of their high T c s (on the order of 100 K). The discovery of high T c superconductivity (HTSc) in the bismuthate system Ba 1−x K x BiO 3 (BKBO) more than ten years ago (Cava, Batlogg, Krajewski, Farrow, Jr, White, Short, Peck, and Kometani, 1988;Mattheiss, Gyorgy, and Johnson Jr., 1988;Hinks, Dabrowski, Jorgensen, Mitchell, Richards, Pei, and Shi, 1988) with a T c of 30 K began an equally significant, complementary course of research into the nature of HTSc for the following reasons: (1) it contains no copper, (2) it is an isotropic conductor, (3) it has no evident magnetic ordering off stoichiometry, (4) its superconductivity occurs at the boundary of a metal-insulator transition (a commonality with the cuprates) (Hinks, Dabrowski, Jorgensen, Mitchell, Richards, Pei, and Shi, 1988;Dabrowski, Hinks, Jorgensen, Kalia, Vashishta, Richards, a.…”