APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session S48: Invited Session: Multi-orbital Effects and Pairing Symmetry in Iron-Based Superconductors
8:00 AM–11:00 AM,
Thursday, March 6, 2014
Room: Mile High Ballroom 1A-1B
Sponsoring
Unit:
DCMP
Chair: Andrey Chubukov, University of Wisconsin-Madison
Abstract ID: BAPS.2014.MAR.S48.4
Abstract: S48.00004 : Pairing symmetry in strongly hole-doped iron-based superconductors
9:48 AM–10:24 AM
Preview Abstract
Abstract
Author:
Fazel Fallah Tafti
(Univ of Sherbrooke)
The fabric of superconductivity in the multiband iron-based superconductors
is woven out of inter-band and intra-band interactions. By tuning the
relative strength of different pairing interactions via external parameters
such as pressure we can tune the pairing symmetry of these multiband
superconductors.
I will present experimental evidence for a pressure induced change of
pairing state in the fully hole-doped iron-based superconductor KFe2As2. Our
main experimental finding is a sharp reversal in the pressure dependence of
Tc at a critical pressure Pc $=$ 18 kbar [1]. Compared to previous reports
on two separate superconducting domes in fully electron-doped chalcogenides,
our discovery points to several novel aspects:
(a) Pc is very low, meaning structural changes are negligible;
(b) Tc remains finite through the transition, suggesting the phase
transition is confined within the superconducting state;
(c) No anomalies are observed in the normal state properties, ruling out the
possibility of a Lifshitz transition;
(d) The two superconducting states manifest a different sensitivity to
disorder.
These observations lead us to conclude that the sharp reversal of Tc at the
critical pressure signals a phase transition between two different pairing
symmetries in KFe2As2: a transition which leaves no traces in the normal
state properties. Theoretical calculations formulate such a phase transition
between different pairing states favored by different inelastic scattering
processes [2]. We explore this hypothesis by tracing Tc versus inelastic
scattering and demonstrate that below the critical pressure, Tc correlates
with inelastic scattering but above the critical pressure, Tc anticorrelates
with inelastic scattering. This is consistent with different channels of
interactions giving rise to different pairing symmetries and pressure simply
tunes the relative strength of these interactions.
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[1] F. F. Tafti \textit{et al}., Nature Physics \textbf{9}, 349 (2013).\\[0pt]
[2] R. M. Fernandes and A. J. Millis, Physical Review Letters \textbf{110},
117004 (2013).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.S48.4