Muon Spin Rotation as a Probe of Superconductivity

Muon Spin Rotation as a
Probe of Superconductivity
Graeme M. Luke
McMaster University
Friday, November 15, 13
Conventional vs. Unconventional Superconductivity
Δ=Δ
Δ
• Δ(k) has symmetry of crystal
• Usually take Δ(k)=Δ (s-wave)
Friday, November 15, 13
Δ=0
• Δ(k) has lower symmetry
• Possible gap nodes
• Other possible broken symmetries
Superconductors at TRIUMF (incomplete)
• Conventional: Nb cavities for accelerator applications
• High Tc: La2-xBaxCuO4, YBa2Cu3O7,...
• Heavy Fermion: UPt3, UBe13, CeCu2Si2, URu2Si2
• Fullerenes: M3C60
• Organics (TMTSF)2ClO4, (BEDT-TTF)2Cu(NCS)2
• Bismuthates: (Ba,K)BiO3
• Borocarbides: YNi2B2C, HoNi2B2C,...
• Aldrich: MgB2
• Sr2RuO4: Topological state for quantum computing?
• Iron Pnictides: ReOFeAs, AeFe2As2, MFeAs, FeTe,...
• non-centrosymmetric
• CuxBi2Se3, In1-xSnxTe, (Ir,M)Te2...
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Capabilities
Low Background
DR: 20mK, 5T
HiTime: 7.5T, 1GHz, 2K
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High Pressure:
22kbar, 2.5K,
55% sample
Pnictide Superconductivity
Re(O,F)FeAs
1111
TC up to 55K
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AeFe2As2
122
TC up to 38K
MFeAs
111
TC up to 33K
Pnictide Superconductivity
Re(O,F)FeAs
1111
TC up to 55K
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AeFe2As2
122
TC up to 38K
MFeAs
111
TC up to 33K
Magnetic Order in Pnictides
Carlo et al., Phys. Rev. Lett. 102, 087001 (2009)
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BaFe2As2 - 122
Aczel et al., Phys. Rev. B 78, 214503 (2008)
Goko et al., PRB 80, 024508 (2009).
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Superconductivity and Magnetic Order Phase Coexistence
Arguello et al., submitted to Nature Physics (2013).
Friday, November 15, 13
Loss of Magnetic Order - Quantum Criticality?
Arguello et al., submitted to Nature Physics (2013).
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Ba(Fe1-xCox)2As2 Superfluid Properties
Williams et al., PRB 80, 094501 (2009).
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Ba(Fe1-xCox)2As2 Superfluid Properties
s±➞d gap
with Co doping ↑
Text
Recall “Uemura plot”
Williams et al., PRB 82, 094512 (2010).
Uemura et al., PRL 62, 2317 (1989)
832 citations
Uemura et al., PRL 66, 2665 (1991)
513 citations
Friday, November 15, 13
Cuprates: Pseudogap - Orbital Currents?
Bloc<0.2G
41G expected from
neutron scattering
MacDougall et al., PRL 101, 017001 (2008).
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Topological Superconductivity in CuxBi2Se3 & Sn1-xInxTe
Sasaki et al., PRL 107, 217001 (2011).
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Sr2RuO4 : kx±iky Topological Superconductor
Nature 394 558 (1998)
485 citations
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Search for Broken Time Reversal Symmetry
T. Goko et al., unpublished (2013).
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Superfluid Density
Long penetration depth: weak relaxation
Will benefit from M.O.D.
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Superfluid Density
Both axes * 10
Cu0.3Bi2Se3
Sn0.7In0.3Te
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Thanks to...
• J.P. Carlo
• PhD (Columbia)
• Postdoc (McMaster)
• Dept. of Physics, Villanova
• A. Aczel
• PhD (McMaster)
• Postdoc (ORNL)
• Instrument Scientist (ORNL)
• G. MacDougall
• PhD (McMaster)
• Postdoc (ORNL)
• Dept. of Physics, University of Illinois at Urbana-Champaign
• T.J. Williams
• PhD (McMaster)
• Wigner Fellow (ORNL)
• T. Goko
• postdoc (Columbia)
• postdoc (PSI)
• C. Arguello
• PhD candidate (Columbia)
• Y.J. Uemura (Columbia)
Friday, November 15, 13