Polaronic behavior in a weak-coupling superconductor
Abstract
We report the nature of superconductivity in the dilute semiconductor SrTiO3 has remained an open question for more than 50 y. The extremely low carrier densities (1018–1020 cm-3) at which superconductivity occurs suggest an unconventional origin of superconductivity outside of the adiabatic limit on which the Bardeen–Cooper–Schrieffer (BCS) and Migdal–Eliashberg (ME) theories are based. We take advantage of a newly developed method for engineering band alignments at oxide interfaces and access the electronic structure of Nb-doped SrTiO3, using high-resolution tunneling spectroscopy. We observe strong coupling to the highest-energy longitudinal optic (LO) phonon branch and estimate the doping evolution of the dimensionless electron–phonon interaction strength (λ). Upon cooling below the superconducting transition temperature (Tc), we observe a single superconducting gap corresponding to the weak-coupling limit of BCS theory, indicating an order of magnitude smaller coupling (λBCS≈0.1). These results suggest that despite the strong normal state interaction with electrons, the highest LO phonon does not provide a dominant contribution to pairing. Finally, they further demonstrate that SrTiO3 is an ideal system to probe superconductivity over a wide range of carrier density, adiabatic parameter, and electron–phonon coupling strength.
- Authors:
-
[5];
- Stanford Univ., CA (United States). Department of Applied Physics and Geballe Laboratory for Advanced Materials; SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Sciences
- Stanford Univ., CA (United States). Department of Applied Physics and Geballe Laboratory for Advanced Materials
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Sciences
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Sciences; Stanford Univ., CA (United States). Dept. of Physics
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Sciences; Stanford Univ., CA (United States). Geballe Laboratory for Advanced Materials
- Univ. of Tennessee, Knoxville, TN (United States). Department of Physics and Astronomy
- Publication Date:
- Research Org.:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
- OSTI Identifier:
- 1426490
- Grant/Contract Number:
- AC02-76SF00515
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Proceedings of the National Academy of Sciences of the United States of America
- Additional Journal Information:
- Journal Volume: 115; Journal Issue: 7; Journal ID: ISSN 0027-8424
- Publisher:
- National Academy of Sciences, Washington, DC (United States)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; superconductivity; electronic structure; polaron; oxide interface
Citation Formats
Swartz, Adrian G., Inoue, Hisashi, Merz, Tyler A., Hikita, Yasuyuki, Raghu, Srinivas, Devereaux, Thomas P., Johnston, Steven, and Hwang, Harold Y. Polaronic behavior in a weak-coupling superconductor. United States: N. p., 2018.
Web. doi:10.1073/pnas.1713916115.
Swartz, Adrian G., Inoue, Hisashi, Merz, Tyler A., Hikita, Yasuyuki, Raghu, Srinivas, Devereaux, Thomas P., Johnston, Steven, & Hwang, Harold Y. Polaronic behavior in a weak-coupling superconductor. United States. https://doi.org/10.1073/pnas.1713916115
Swartz, Adrian G., Inoue, Hisashi, Merz, Tyler A., Hikita, Yasuyuki, Raghu, Srinivas, Devereaux, Thomas P., Johnston, Steven, and Hwang, Harold Y. Tue .
"Polaronic behavior in a weak-coupling superconductor". United States. https://doi.org/10.1073/pnas.1713916115. https://www.osti.gov/servlets/purl/1426490.
@article{osti_1426490,
title = {Polaronic behavior in a weak-coupling superconductor},
author = {Swartz, Adrian G. and Inoue, Hisashi and Merz, Tyler A. and Hikita, Yasuyuki and Raghu, Srinivas and Devereaux, Thomas P. and Johnston, Steven and Hwang, Harold Y.},
abstractNote = {We report the nature of superconductivity in the dilute semiconductor SrTiO3 has remained an open question for more than 50 y. The extremely low carrier densities (1018–1020 cm-3) at which superconductivity occurs suggest an unconventional origin of superconductivity outside of the adiabatic limit on which the Bardeen–Cooper–Schrieffer (BCS) and Migdal–Eliashberg (ME) theories are based. We take advantage of a newly developed method for engineering band alignments at oxide interfaces and access the electronic structure of Nb-doped SrTiO3, using high-resolution tunneling spectroscopy. We observe strong coupling to the highest-energy longitudinal optic (LO) phonon branch and estimate the doping evolution of the dimensionless electron–phonon interaction strength (λ). Upon cooling below the superconducting transition temperature (Tc), we observe a single superconducting gap corresponding to the weak-coupling limit of BCS theory, indicating an order of magnitude smaller coupling (λBCS≈0.1). These results suggest that despite the strong normal state interaction with electrons, the highest LO phonon does not provide a dominant contribution to pairing. Finally, they further demonstrate that SrTiO3 is an ideal system to probe superconductivity over a wide range of carrier density, adiabatic parameter, and electron–phonon coupling strength.},
doi = {10.1073/pnas.1713916115},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 7,
volume = 115,
place = {United States},
year = {2018},
month = {1}
}
Free Publicly Available Full Text
Publisher's Version of Record
Other availability
Search WorldCat to find libraries that may hold this journal
Cited by: 48 works
Citation information provided by
Web of Science
Web of Science
Figures / Tables:
FIG. 1: Dipole controlled interfaces for high resolution tunneling spectroscopy of Nb:SrTiO3. Schematic diagrams of the tunneling junction depicting: A, the atomic layer stacking with an interfacial LaAlO3 dipole layer which serves as the tunneling barrier; B, device measurement geometry; C-D, resulting band diagrams without and with the insertion ofmore »
All figures and tables
(5 total)
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.
Works referenced in this record:
Tailoring the nature and strength of electron–phonon interactions in the SrTiO3(001) 2D electron liquid
journal, April 2016
- Wang, Z.; McKeown Walker, S.; Tamai, A.
- Nature Materials, Vol. 15, Issue 8
Critical Doping for the Onset of a Two-Band Superconducting Ground State in
journal, May 2014
- Lin, Xiao; Bridoux, German; Gourgout, Adrien
- Physical Review Letters, Vol. 112, Issue 20
Observation of a two-dimensional liquid of Fröhlich polarons at the bare SrTiO3 surface
journal, October 2015
- Chen, Chaoyu; Avila, José; Frantzeskakis, Emmanouil
- Nature Communications, Vol. 6, Issue 1
Dielectric, infrared, and Raman response of undoped ceramics: Evidence of polar grain boundaries
journal, October 2001
- Petzelt, J.; Ostapchuk, T.; Gregora, I.
- Physical Review B, Vol. 64, Issue 18
Properties of boson-exchange superconductors
journal, October 1990
- Carbotte, J. P.
- Reviews of Modern Physics, Vol. 62, Issue 4
Theory of Superconductivity in Polar Semiconductors and Its Application to N-Type Semiconducting SrTiO 3
journal, October 1980
- Takada, Yasutami
- Journal of the Physical Society of Japan, Vol. 49, Issue 4
Lead Phonon Spectrum Calculated from Superconducting Density of States
journal, January 1965
- McMillan, W. L.; Rowell, J. M.
- Physical Review Letters, Vol. 14, Issue 4
Enhanced Electrical Transparency by Ultrathin LaAlO 3 Insertion at Oxide Metal/Semiconductor Heterointerfaces
journal, February 2015
- Yajima, Takeaki; Minohara, Makoto; Bell, Christopher
- Nano Letters, Vol. 15, Issue 3
Electron tunneling in indium-SrTiO3: Nb Schottky barriers
journal, November 1969
- Sroubek, Z.
- Solid State Communications, Vol. 7, Issue 21
Strong energy–momentum dispersion of phonon-dressed carriers in the lightly doped band insulator SrTiO 3
journal, February 2010
- Meevasana, W.; Zhou, X. J.; Moritz, B.
- New Journal of Physics, Vol. 12, Issue 2
Empirical electron-phonon values from resistivity of cubic metallic elements
journal, August 1987
- Allen, Philip B.
- Physical Review B, Vol. 36, Issue 5
Local Measurement of the Eliashberg Function of Pb Islands: Enhancement of Electron-Phonon Coupling by Quantum Well States
journal, January 2015
- Schackert, Michael; Märkl, Tobias; Jandke, Jasmin
- Physical Review Letters, Vol. 114, Issue 4
Band Edge Engineering of Oxide Photoanodes for Photoelectrochemical Water Splitting: Integration of Subsurface Dipoles with Atomic-Scale Control
journal, January 2016
- Hikita, Yasuyuki; Nishio, Kazunori; Seitz, Linsey C.
- Advanced Energy Materials, Vol. 6, Issue 7
Superconductivity at very low density: The case of strontium titanate
journal, December 2016
- Ruhman, Jonathan; Lee, Patrick A.
- Physical Review B, Vol. 94, Issue 22
Effective masses of electrons in n-type SrTiO3 determined from low-temperature specific heat capacities
journal, April 2007
- Ahrens, M.; Merkle, R.; Rahmati, B.
- Physica B: Condensed Matter, Vol. 393, Issue 1-2
Superconducting Transition Temperatures of Semiconducting SrTi
journal, November 1967
- Koonce, C. S.; Cohen, Marvin L.; Schooley, J. F.
- Physical Review, Vol. 163, Issue 2
Superconductivity in the two-dimensional electron gas induced by high-energy optical phonon mode and large polarization of the substrate
journal, July 2016
- Rosenstein, Baruch; Shapiro, B. Ya.; Shapiro, I.
- Physical Review B, Vol. 94, Issue 2
A ferroelectric quantum phase transition inside the superconducting dome of Sr1−xCaxTiO3−δ
journal, April 2017
- Rischau, Carl Willem; Lin, Xiao; Grams, Christoph P.
- Nature Physics, Vol. 13, Issue 7
Accurate determination of the far-infrared dispersion in SrTi by hyper-Raman spectroscopy
journal, September 1981
- Vogt, H.; Rossbroich, G.
- Physical Review B, Vol. 24, Issue 6
Electric field control of the LaAlO3/SrTiO3 interface ground state
journal, December 2008
- Caviglia, A. D.; Gariglio, S.; Reyren, N.
- Nature, Vol. 456, Issue 7222
Common Fermi-liquid origin of resistivity and superconductivity in -type SrTiO
journal, November 2011
- van der Marel, D.; van Mechelen, J. L. M.; Mazin, I. I.
- Physical Review B, Vol. 84, Issue 20
Two-band superconductivity in doped SrTiO films and interfaces
journal, January 2013
- Fernandes, R. M.; Haraldsen, J. T.; Wölfle, P.
- Physical Review B, Vol. 87, Issue 1
Structure and correlation effects in semiconducting
journal, June 2010
- Chang, Young Jun; Bostwick, Aaron; Kim, Yong Su
- Physical Review B, Vol. 81, Issue 23
Vanishing Hall Coefficient in the Extreme Quantum Limit in Photocarrier-Doped
journal, August 2008
- Kozuka, Y.; Susaki, T.; Hwang, H. Y.
- Physical Review Letters, Vol. 101, Issue 9
Electron-Phonon Interaction and Charge Carrier Mass Enhancement in
journal, June 2008
- van Mechelen, J. L. M.; van der Marel, D.; Grimaldi, C.
- Physical Review Letters, Vol. 100, Issue 22
Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
journal, November 2014
- Lee, J. J.; Schmitt, F. T.; Moore, R. G.
- Nature, Vol. 515, Issue 7526
Interface superconductor with gap behaviour like a high-temperature superconductor
journal, October 2013
- Richter, C.; Boschker, H.; Dietsche, W.
- Nature, Vol. 502, Issue 7472
Superconductivity in Semiconducting SrTi
journal, April 1964
- Schooley, J. F.; Hosler, W. R.; Cohen, Marvin L.
- Physical Review Letters, Vol. 12, Issue 17
Inelastic electron tunnelling spectroscopy
journal, March 1985
- Adkins, C. J.; Phillips, W. A.
- Journal of Physics C: Solid State Physics, Vol. 18, Issue 7
Two-Band Superconductivity in Nb-Doped SrTi
journal, October 1980
- Binnig, G.; Baratoff, A.; Hoenig, H. E.
- Physical Review Letters, Vol. 45, Issue 16
Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System
journal, September 2016
- Chen, Zhuoyu; Yuan, Hongtao; Xie, Yanwu
- Nano Letters, Vol. 16, Issue 10
Electron-phonon interactions from first principles
journal, February 2017
- Giustino, Feliciano
- Reviews of Modern Physics, Vol. 89, Issue 1
Molecular Vibration Spectra by Electron Tunneling
journal, November 1966
- Jaklevic, R. C.; Lambe, J.
- Physical Review Letters, Vol. 17, Issue 22
Direct Measurement of Quasiparticle-Lifetime Broadening in a Strong-Coupled Superconductor
journal, November 1978
- Dynes, R. C.; Narayanamurti, V.; Garno, J. P.
- Physical Review Letters, Vol. 41, Issue 21
Electronic Raman scattering in superconductors as a probe of anisotropic electron pairing
journal, June 1995
- Devereaux, T. P.; Einzel, D.
- Physical Review B, Vol. 51, Issue 22
Quantum Critical Origin of the Superconducting Dome in
journal, December 2015
- Edge, Jonathan M.; Kedem, Yaron; Aschauer, Ulrich
- Physical Review Letters, Vol. 115, Issue 24
Dominant Mobility Modulation by the Electric Field Effect at the Interface
journal, November 2009
- Bell, C.; Harashima, S.; Kozuka, Y.
- Physical Review Letters, Vol. 103, Issue 22
Multiband Superconductivity Due to the Electron–LO–Phonon Interaction in Strontium Titanate and on a SrTiO3/LaAlO3 Interface
journal, August 2016
- Klimin, S. N.; Tempere, J.; Devreese, J. T.
- Journal of Superconductivity and Novel Magnetism, Vol. 30, Issue 3
Tuning Band Alignment Using Interface Dipoles at the Pt/Anatase TiO 2 Interface
journal, October 2015
- Tachikawa, Takashi; Minohara, Makoto; Hikita, Yasuyuki
- Advanced Materials, Vol. 27, Issue 45
Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal–insulator transition
journal, March 2014
- Mundy, Julia A.; Hikita, Yasuyuki; Hidaka, Takeaki
- Nature Communications, Vol. 5, Issue 1
Dramatic mobility enhancements in doped SrTiO3 thin films by defect management
journal, July 2010
- Kozuka, Y.; Hikita, Y.; Bell, C.
- Applied Physics Letters, Vol. 97, Issue 1
Two-dimensional normal-state quantum oscillations in a superconducting heterostructure
journal, November 2009
- Kozuka, Y.; Kim, M.; Bell, C.
- Nature, Vol. 462, Issue 7272, p. 487-490
Superconductivity in doped semiconductors
journal, July 2015
- Bustarret, E.
- Physica C: Superconductivity and its Applications, Vol. 514
Evidence for ubiquitous strong electron–phonon coupling in high-temperature superconductors
journal, August 2001
- Lanzara, A.; Bogdanov, P. V.; Zhou, X. J.
- Nature, Vol. 412, Issue 6846
Superconducting Interfaces Between Insulating Oxides
journal, August 2007
- Reyren, N.; Thiel, S.; Caviglia, A. D.
- Science, Vol. 317, Issue 5842
Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface
journal, September 2011
- Bert, Julie A.; Kalisky, Beena; Bell, Christopher
- Nature Physics, Vol. 7, Issue 10, p. 767-771
Tunneling Spectroscopy in GaAs
journal, September 1967
- Conley, J. W.; Mahan, G. D.
- Physical Review, Vol. 161, Issue 3
Electron—phonon Coupling and the Superconducting Phase Diagram of the LaAlO3—SrTiO3 Interface
journal, July 2015
- Boschker, Hans; Richter, Christoph; Fillis-Tsirakis, Evangelos
- Scientific Reports, Vol. 5, Issue 1
Quantum Critical Origin of the Superconducting Dome in SrTiO₃
text, January 2015
- Aschauer, Ulrich Johannes; Balatsky, Alexander V.; Spaldin, Nicola A.
- American Physical Society
Inelastic electron tunnelling spectroscopy
journal, July 1983
- Payne, M. C.; Inkson, J. C.
- Journal of Physics C: Solid State Physics, Vol. 16, Issue 21
Vanishing Hall Coefficient in the Extreme Quantum Limit in Photocarrier-Doped SrTiO3
text, January 2008
- Kozuka, Y.; Susaki, T.; Hwang, H. Y.
- arXiv
Dramatic Mobility Enhancements in Doped SrTiO3 Thin Films by Defect Management
text, January 2010
- Kozuka, Y.; Hikita, Y.; Bell, C.
- arXiv
Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface
text, January 2011
- Bert, J. A.; Kalisky, B.; Bell, C.
- arXiv
Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
text, January 2013
- Lee, J. J.; Schmitt, F. T.; Moore, R. G.
- arXiv
Superconductivity at very low density: the case of strontium titanate
text, January 2016
- Ruhman, Jonathan; Lee, Patrick A.
- arXiv
Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System
text, January 2018
- Chen, Zhuoyu; Yuan, Hongtao; Xie, Yanwu
- arXiv
Electronic Raman scattering in superconductors as a probe of anisotropic electron pairing
text, January 1994
- Devereaux, T. P.; Einzel, D.
- arXiv
Works referencing / citing this record:
Superconductivity in SrTiO3: Dielectric Function Method for Non-Parabolic Bands
journal, January 2019
- Klimin, S. N.; Tempere, J.; Devreese, J. T.
- Journal of Superconductivity and Novel Magnetism, Vol. 32, Issue 9
Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO
journal, June 2018
- Riley, J. M.; Caruso, F.; Verdi, C.
- Nature Communications, Vol. 9, Issue 1
Gap suppression at a Lifshitz transition in a multi-condensate superconductor
journal, May 2019
- Singh, G.; Jouan, A.; Herranz, G.
- Nature Materials, Vol. 18, Issue 9
Inhomogeneous barrier heights at dipole-controlled SrRuO 3 /Nb:SrTiO 3 Schottky junctions
journal, November 2018
- Yajima, T.; Minohara, M.; Bell, C.
- Applied Physics Letters, Vol. 113, Issue 22
Multiorbital ferroelectric superconductivity in doped
journal, September 2019
- Kanasugi, Shota; Yanase, Youichi
- Physical Review B, Vol. 100, Issue 9
Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in
journal, October 2018
- Swartz, Adrian G.; Cheung, Alfred K. C.; Yoon, Hyeok
- Physical Review Letters, Vol. 121, Issue 16
Decoupling Carrier Concentration and Electron-Phonon Coupling in Oxide Heterostructures Observed with Resonant Inelastic X-Ray Scattering
journal, December 2018
- Meyers, D.; Nakatsukasa, Ken; Mu, Sai
- Physical Review Letters, Vol. 121, Issue 23
Quantum ferroelectric instabilities in superconducting
journal, October 2018
- Arce-Gamboa, J. R.; Guzmán-Verri, G. G.
- Physical Review Materials, Vol. 2, Issue 10
Chemical control of the electrical surface properties in donor-doped transition metal oxides
journal, April 2019
- Andrä, M.; Bluhm, H.; Dittmann, R.
- Physical Review Materials, Vol. 3, Issue 4
Enhancing superconductivity in SrTiO 3 films with strain
journal, April 2019
- Ahadi, Kaveh; Galletti, Luca; Li, Yuntian
- Science Advances, Vol. 5, Issue 4
Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO
text, January 2018
- Riley, J. M.; Caruso, F.; Verdi, C.
- Deutsches Elektronen-Synchrotron, DESY, Hamburg
Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO
journal, June 2018
- Riley, J. M.; Caruso, F.; Verdi, C.
- Nature Communications, Vol. 9, Issue 1
Figures / Tables found in this record:
Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.