Direct submillimeter absorptivity measurements on epitaxial Ba1-xKxBiO3 films at 2K

D. Miller; P. L. Richards; E. J. Nicol; E. S. Hellman; E. H. Hartford; C. E. Platt; R. A. Schweinfurth; D. J. VanHarlingen; J. Amano

doi:10.1016/0022-3697(93)90186-U

Direct submillimeter absorptivity measurements on epitaxial Ba_1-xK_xBiO₃ films at 2K

D. Miller, P. L. Richards, E. J. Nicol, E. S. Hellman, E. H. Hartford, C. E. Platt, R. A. Schweinfurth, D. J. VanHarlingen, J. Amano

Physics

Research output: Contribution to journal › Article › peer-review

Abstract

We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba_0.6K_0.4BiO₃ from 30 cm^-1 to 700 cm^-1. These films were grown on MgO and SrTiO₃ substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5k_BT_c. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Our results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strong coupling Eliashberg theory using α²F(ω) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.

Original language	English (US)
Pages (from-to)	1323-1326
Number of pages	4
Journal	Journal of Physics and Chemistry of Solids
Volume	54
Issue number	10
DOIs	https://doi.org/10.1016/0022-3697(93)90186-U
State	Published - Oct 1993

Keywords

BKBO
high temperature superconductivity
infrared spectroscopy
thin films

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

Online availability

10.1016/0022-3697(93)90186-U

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Cite this

@article{bcba9329a2824224b9855816380ca154,

title = "Direct submillimeter absorptivity measurements on epitaxial Ba1-xKxBiO3 films at 2K",

abstract = "We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba0.6K0.4BiO3 from 30 cm-1 to 700 cm-1. These films were grown on MgO and SrTiO3 substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5kBTc. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Our results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strong coupling Eliashberg theory using α2F(ω) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.",

keywords = "BKBO, high temperature superconductivity, infrared spectroscopy, thin films",

author = "D. Miller and Richards, {P. L.} and Nicol, {E. J.} and Hellman, {E. S.} and Hartford, {E. H.} and Platt, {C. E.} and Schweinfurth, {R. A.} and VanHarlingen, {D. J.} and J. Amano",

note = "Funding Information: ACKNOWLEDGMENTS This work was supportedin part by the Director,O ffice of Energy ResearchO, ffice of Basic Energy SciencesM, aterialsS ciencesD ivision of theU .S. Departmenotf Energyu nderc ontractN o. DE-AC03-76SF00098 (D.M. and P.L.R.) and by the NSF Science and Technology Center for Superconductivituyn der Grant No. STC-90-09854(C .E.P., R.A.S. and D.J.V.).",

year = "1993",

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doi = "10.1016/0022-3697(93)90186-U",

language = "English (US)",

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pages = "1323--1326",

journal = "Journal of Physics and Chemistry of Solids",

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TY - JOUR

T1 - Direct submillimeter absorptivity measurements on epitaxial Ba1-xKxBiO3 films at 2K

AU - Miller, D.

AU - Richards, P. L.

AU - Nicol, E. J.

AU - Hellman, E. S.

AU - Hartford, E. H.

AU - Platt, C. E.

AU - Schweinfurth, R. A.

AU - VanHarlingen, D. J.

AU - Amano, J.

N1 - Funding Information: ACKNOWLEDGMENTS This work was supportedin part by the Director,O ffice of Energy ResearchO, ffice of Basic Energy SciencesM, aterialsS ciencesD ivision of theU .S. Departmenotf Energyu nderc ontractN o. DE-AC03-76SF00098 (D.M. and P.L.R.) and by the NSF Science and Technology Center for Superconductivituyn der Grant No. STC-90-09854(C .E.P., R.A.S. and D.J.V.).

PY - 1993/10

Y1 - 1993/10

N2 - We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba0.6K0.4BiO3 from 30 cm-1 to 700 cm-1. These films were grown on MgO and SrTiO3 substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5kBTc. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Our results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strong coupling Eliashberg theory using α2F(ω) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.

AB - We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba0.6K0.4BiO3 from 30 cm-1 to 700 cm-1. These films were grown on MgO and SrTiO3 substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5kBTc. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Our results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strong coupling Eliashberg theory using α2F(ω) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.

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KW - infrared spectroscopy

KW - thin films

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