Decisive role of hybridized electronic states on the appearance of superconductivity in Ba1−xKxMO3 (M=Bi,Sb),Physical Review B

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Decisive role of hybridized electronic states on the appearance of superconductivity in Ba1−xKxMO3 (M=Bi,Sb)
Physical Review B ( IF 3.2 ) Pub Date : 2024-09-10 , DOI: 10.1103/physrevb.110.125120
Julien Varignon _{1,

2,

3}

Affiliation

The observation of superconductivity (SC) in hole-doped antimonates

B a_{1 - x} K_{x} Sb O_{3}

(BKSO), isoelectronic compounds to bismuthate

B a_{1 - x} K_{x} Bi O_{3}

(BKBO) SCs, enables a pathway to clarify the role of hybridizations between electronic states of metals and ligands on the emergence of SC. Herein, using first-principles simulations, the localized electronic structure of antimonates is demonstrated to produce various charge and bond orderings (CBOs) up to

x = 0.6

, hence hindering the appearance of a SC state. This is in contrast with bismuthates where the formation of charge orderings is suppressed by doping effects and their native hybridized electronic structure. Although quenched by doping effects, the CBOs mediate the Cooper pair formation, and the resulting electron-phonon coupling reproduces the experimental facts such as a larger

T_{c}

in BKSO than in BKBO for

x > 0.65

and a maximal

T_{c}

\sim 30 K

observed at

x = 0.4 - 0.5

for BKBO. The latter point is ascribed to a soft phonon mode at

x = 0.5

, while the former observation is ascribed to an intrinsically stronger coupling between lattice distortions and electrons in

BaSb O_{3}

. Although materials with a localized electronic structure could warrant larger

{T^{'}}_{c} s

, the main drawback is the resilience of such compounds to form a metallic state, and hence SC emerges far away of soft phonons possessing a strong coupling with the electronic structure.

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