Optical study of Ba0.6K0.4BiO3 single crystals: Normal and superconducting properties
A. V. Puchkov, T. Timusk, W. D. Mosley, R. N. Shelton
DOI 10.1103/PhysRevB.50.4144 · Physical Review B
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Abstract
We report absolute reflectivity measurements on Ba0.6K0.4BiO3 in both normal and superconducting states. The superconducting-gap value was determined to be 2Δ=90±10 cm−1, which gives 2Δ/kBTc=4.2±0.5, consistent with previous experiments. However, finite absorption below 2Δ frequency was found. No Holstein shift of the phonon-related spectrum was observed. Optical conductivity below 2 eV consists of two contributions: a narrow (≤350 cm−1) Drude-like part (Drude component) and an overdamped midinfrared component. We suggest that while the carriers responsible for the Drude contribution form the superfluid at T<Tc, the carriers responsible for the midinfrared one remain normal and account for the finite absorption inside the superconducting gap. The value of the London penetration depth λL was determined to be (4550±300) Å. Anomalous temperature dependence of reflectivity at temperatures above ∼120–150 K was observed.
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. | 30.8 | Pressure not reported | onset |
| Ba0.6K0.4BiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 30.8 | Pressure not reported | onset |
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