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SUMMARY:Critical dopings and superconducting domes in doped SrTiO3 - Kamra
 n Behnia\, ESPCI\, Paris.
DTSTART:20131023T101500Z
DTEND:20131023T111500Z
UID:TALK47185@talks.cam.ac.uk
CONTACT:Michael Sutherland
DESCRIPTION:In doped SrTiO3\, superconductivity persists down to an except
 ionally low concentration of mobile electrons. In this concentration range
 \, the Fermi energy becomes more than one order of magnitude lower than th
 e Debye energy.This severely restricts the relevant energy window for pair
 ing and eliminates the conventional picture of superconductivity\, in whic
 h electrons at Fermi level exchange virtual phonons  of typical Debye ener
 gy. As  the sytem is doped\, theory expects multiple bands  to be successi
 vely filled in the normal state. On the other hand\,  experiment has detec
 ted distinct superconducting gaps near optimal doping.  We present a study
  of quantum oscillations and superconducting transition temperature\, whic
 h clarifies the link between these two features. As the carrier density is
  tuned over three orders of magnitude\,  two critical doping levels are id
 entified by our experiment. They correspond to the filling thresholds of t
 he two upper bands.Tc presents a pronounced hump in the vicinity of the fi
 rst critical doping\, separating a single-band and a two-band superconduct
 or. The one-band superconductor below this critical doping emerges as a st
 rong-coupling extremely dilute superconductor.
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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