Theory of a higher-order phase transition: The superconducting transition in Ba0.6K0.4BiO3

Pradeep Kumar

doi:10.1103/PhysRevB.68.064505

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Theory of a higher-order phase transition: The superconducting transition in Ba0.6K0.4BiO3

Pradeep Kumar

DOI 10.1103/PhysRevB.68.064505 · Physical Review B

T1

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Abstract

We describe here the properties expected of a higher-order (with emphasis on the order fourth) phase transition. The order is identified in the sense first noted by Ehrenfest, namely, in terms of the temperature dependence of the ordered-state free energy near the phase boundary. We have derived an equation for the phase boundary in terms of the discontinuities in thermodynamic observables, developed a Ginzburg-Landau free energy and studied the thermodynamic and magnetic properties. We also discuss the current status of experiments on Ba0.6K0.4BiO3 and other BiO3-based superconductors and the expectations for parameters and examine alternative explanations of the experimental results.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Ba0.6K0.4BiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32	Pressure not reported	unknown
BaPbxBi1-xO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	11	Pressure not reported	unknown
Ba1-xRbxBiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	Pressure not reported	unknown
SrBiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	12.5	Pressure not reported	unknown
K1-xBi1-xO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10	Pressure not reported	unknown
Ba(Pb,Sb)O3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.5	Pressure not reported	unknown