Electronic tuning in CeCoIn5:
a dirty job
Eric Bauer
Ryan Baumbach
Kris Gofryk
Xin Lu
M.N. Ou (Owen)
Tian Shang
Joe Thompson
Paul Tobash
Vladamir Sidorov
Jianxin Zhu
(LANL)
S. Stoyko
A. Mar (U. Alberta)
Hiroshi Yasuoka (JAEA)
Tuson Park (SKKU)
Zach Fisk (UC Irvine)
Filip Ronning
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Los Alamos National Lab
Outline

Motivation

“Dirt” in CeCoIn5

(K. Gofryk, et al. PRL 109, 186402 (2012))

Dopants locally modify hybridization

Transition metal layers are NOT charge reservoir layers. (Sn vs. Pt doping)

Weak pair breaking effects in CeCoIn5 and quantifying it.

Normal state transport
Conclusions
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Reducing Dimensionality
Ce2MIn8
CeM2In7
CeMIn5
Increasing Bandwidth
13 compounds in
this family are
superconductors
CeIn3
Tc = 0.2 K
Tc = 2.3 K
Tc = 2.1 K
NpPd5Al2
Tc = 5 K
PuMGa5
Tc = 18.5 K
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Tc = 2.1 K
Reducing dimensionality to maximize pairing
Enhance matching of G(q,w) to CQ(q,w) by reducing dimensionality
Monthoux &
Lonzarich, PRB ‘02
Monthoux , Pines, &
Lonzarich, Nature ‘07
CeCoIn5
3D
2D
3D
2D
“Active” layer
“Buffer” layer
CeIn3
“Active” layer
CeCoIn5
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• Prototypical strongly
correlated system
• Quantum Criticality
• Heavy Fermion
• dx2-y2 SC order parameter
Dirt as a microscope
Heavy Fermion formation
Quantum criticality
D(k)=?
I. Mazin Nature ‘10
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Anderson / Abrikosov-Gorkov theories + corollaries
•
For a SC order parameter which DOES NOT change sign
•
•
Non-magnetic impurities are weakly pair breaking
Anderson’s Theorem 1959
Magnetic impurities are strongly pair breaking
Abrikosov-Gorkov theory 1960
• For a SC order parameter which DOES change sign
• Non-magnetic impurities are strongly pair breaking
D2
D2
D1
D1
S=0
S=0
S≠0
D1=D2 ; S=0
 ; S≠0 X
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D1≠D2 ; S=0 X
Debate on Fe-based superconductors
Y. Nakajima, et al. PRB ‘10
S. Onarii and H. Kontani, PRL ‘08
• robustness to non-magnetic impurities may suggest that the
Fe-based superconductors are conventional (s++)
See counter point
P. Hirschfeld, et al. Rep. Prog. Phys. ‘11
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Doping on the active layer: In-site Doping
• There are 2 effects
• (1) Electronic tuning
• (2) Pair breaking
• EXAFS: Doping is
preferentially on In(1) site
M. Daniel, et al PRL ‘05
CeMIn5
R. Urbano, et al PRL ‘07
“Active” layer
Pt for
Co
“Buffer” layer
“Active” layer
Cd,Sn
Snfor
forInIn
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Holes
Electrons
What is the origin of the
different doping behavior?
• Sn (electrons)
• Cd, Hg (holes)
• actual concentrations
used from here on.
Cd, Hg, Sn for In
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The role of the dopant atoms
Ce2
In1
Co
X
• Cd has smaller bandwidth than In
• Sn has larger bandwidth than In
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Ce1
• 2 x 2 x 2 supercell
• doping = 0.025
K. Gofryk, et al PRL ‘12
The role of the dopant atoms
Ce2
In1
Co
X
Ce1
• Cd locally decrease hybridization to Ce J = V 2(1/e +1/(2e +U))
K
fc
f
f
• Sn locally increases hybridization to Ce
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Reversible electronic tuning
JKr
Holes
Electrons
• JKr decreases with hole doping (Cd and Hg)
• JKr increases with electron doping (Sn and Pt)
• Doping creates an inhomogeneous internal field
R. Urbano, et al PRL ‘07
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Similarities in Cd and Hg tuning
Phase Diagrams
DFT
• Cd and Hg doped 115’s have
nearly identical phase diagrams
• DFT calculations with Cd and
Hg impurity atoms give identical
results
C. Booth, et al PRB ‘09
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Electron dopants to distinguish buffer layers
CeMIn5
CeIn3
“Active” layer
“Buffer” layer
Pt for Co
“Active” layer
Sn for In
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Sn vs Pt Tc suppression
• Impurity potential nearly identical for Sn and Pt dopants.
• Implies screening length ≈ unit cell.
• No such thing as “buffer” layers in the 115s.
• Tc → 0 @ r0 ~ 10 mWcm: Can we separate pair breaking and
electronic tuning effects?
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K. Gofryk, et al PRL ‘12
Isolate pair breaking of holes using pressure
L.D. Pham, et al. PRL ‘06
dTcmax/dCd = -5 K/Cd
L.D. Pham, et al. PRL ‘06
• Cd doping reversible with pressure
• Assume that dTc/Hg = dTc/dCd
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Isolate pair breaking of electrons using co-doping
• Tc initially increases
with Hg co-doping
• SC suppressed, but AFM
QC reversible with codoping.
dTc/dSn = -13.3 K/Sn
dTc/dPt = -11.2 K/Pt
• Pt and Sn doping reversible with
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Hg doping
K. Gofryk, et al PRL ‘12
Comparison of pair breaking rates
Holes
dTc/dCd = -5 K/Cd
• Hole doping (AF droplets) is
a significantly weaker pair
breaker for superconductivity
• These are very weak
Electrons
dTc/dSn = -13.3 K/Sn
dTc/dPt = -11.2 K/Pt
suppressions, but how
weak/strong is the impurity
potential? Need 1/t
Cuprates:
dTc/dZn ≈ 2 dTc/dNi
Rare Earths
dTc/dR = -10 K/R
C. Petrovic, et al. PRB ’02
J. Paglione, et al, Nat. Phys. ‘07
Hudson, et al. Nature ‘01
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Extracting 1/t from resistivity
l = 190 – 550 um
R.J. Ormeno, et al. PRL ’02
S. Ozcan, et al, Eur. Lett. ‘03
Sn 0.09; Hg 0.025
Pt 0.09; Hg 0.025
pure
W. Higemoto, et al. JPSJ ‘02
d(1/t)/dCd = 830 K/Cd
d(1/t)/dSn = 330 K/Sn
d(1/t)/dPt = 120 K/Pt
T [K]
1/t =
2
ne Dr/m*
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= Dr/m0
2
l
Comparison of pair breaking rates II
Impurity scattering for non-magnetic defects is remarkably
weak compared with Abrikosov-Gorkov theory
K. Gofryk, et al PRL ‘12
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Could CeCoIn5 be conventional?
Thermal conductivity
Line Nodes!
Upper Critical Field
R. Movshovich, M. Jaime, J. D. Thompson, C. Petrovic, Z. Fisk, P. G. Pagliuso, and J. L. Sarrao, Phys. Rev. Lett. 86,
5152 (2001).
[6] Y. Kohori, Y. Yamato, Y. Iwamoto, T. Kohara, E. D. Bauer, M. B. Maple, and J. L. Sarrao, Phys. Rev. B 64, 134526
Neutron Resonance
(2001).
[7] R. J. Ormeno, A. Sibley, C. E. Gough, S. Sebastian, and I. R. Fisher, Phys. Rev. Lett. 88, 047005 (2002).
[8] K. Izawa, H. Yamaguchi, Y. Matsuda, H. Shishido, R. Settai, and Y. Onuki, Phys. Rev. Lett. 87, 057002 (2001).
[9] H. Aoki, T. Sakakibara, H. Shishido, R. Settai, Y. nuki, P. Miranovi, and K. Machida, Journal of Physics: Condensed
Matter 16, L13 (2004).
NQR
[10] A. Vorontsov and I. Vekhter, Phys. Rev. Lett. 96, 237001 (2006).
[11] K. An, T. Sakakibara, R. Settai, Y. Onuki, M. Hiragi, M. Ichioka, and K. Machida, Phys. Rev. Lett. 104, 037002 (2010).
[12] F. Weickert, P. Gegenwart, H. Won, D. Parker, and K. Maki, Phys. Rev. B 74, 134511 (2006).
[13] W. K. Park, J. L. Sarrao, J. D. Thompson, and L. H. Greene, Phys. Rev. Lett. 100, 177001 (2008).
Specific Heat
[14] A. D. Bianchi, M. Kenzelmann, L. DeBeer-Schmitt, J. S. White, E. M. Forgan, J. Mesot, M. Zolliker, J. Kohlbrecher,
R. Movshovich, E. D. Bauer, J. L. Sarrao, Z. Fisk, C. Petrovi, and M. R. Eskildsen, Science 319, 177 (2008).
[15] N. Hiasa and R. Ikeda, Phys. Rev. Lett. 101, 027001 (2008).
dx2-y2!
[16] C. Stock, C. Broholm, J. Hudis, H. J. Kang, and C. Petrovic, Phys. Rev. Lett. 100, 087001 (2008).
Vortex Lattice
Point Contact Andreev Reflection
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Spectrum of weak non-magnetic pair breaking
experiment
• Conventional
• Cuprate SC’s
• Fe-based SC’s
• CeCoIn5
theory
SC’s
 • Short coherence length
 • Anisotropic scattering
 • Strong coupling
 • Induced magnetic moments
M. Franz, et al. PRB ’02
G. Haran and H. Nagi, PRB ‘98
M.L. Kulic and O.V. Dolgov, PRB ’99
• Coherence length = 5 nm
R. Movshovich, et al. PRL ’01
• Spatial Inhomogeneity
P. Monthoux and D. Pines, PRB ‘94
• DCp/gTc = 4.5
C. Petrovic, et al.
JPCM ’01
E.D. Bauer, et al.
PNAS ’11
• Induced moments with Cd
• Multiband SC
doping
Thermal Conductivity
M. A. Tanatar, et al. PRL ‘05; G. Seyfarth, et al. PRL ‘08
Point
Contact
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Security, LLC for NNSAP.
Rourke, et al. PRL ‘05
NMR: R. Urbano, et al. PRL ’07
Electronic tuning of CeCoIn5: transport
• Sublinear transport
• unusual QCP
• Mirrored by Cp data
• (Fisher-Langer)
• The influence of disorder on
the normal state is still poorly
understood.
• CeIrIn5 has a more
“expected” response to
disorder
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Electronic tuning of CeIrIn5: Cp
Holes
Electrons
• Bulk Tc suppressed with
doping.
• QCP at slight hole doping.
• Pt and Sn doping nearly
identical
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T. Shang, et al unpublished
CeIrIn5: low T transport summary
• Pt and Sn doping nearly
identical
• “expected” behavior for a
2D AFM QCP.
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T. Shang, et al unpublished
Revisiting dimensionality in the 115 family
Monthoux , Pines, &
Lonzarich, Nature ‘07
CePt2In7
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CeIn3
Possible future direction
LDA
Wannierization
Impurity potentials
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Tight Binding
Model Hamiltonians (+U)
SC instability
Doniach Diagram
Conclusions
Doping CeMIn5 has both a pair breaking effect and an electronic
tuning effect both of which influence Tc.
Similarity of Pt and Sn doping implies no “buffer” layer in CeMIn5.
Electron and hole doping locally modifies the hybridization and is
reversible w.r.t. magnetism
Pair breaking is remarkably weak compared to Abrikosov-Gorkov
theory
hole dopants are weaker than rare earth or electron dopants.
K. Gofryk, et al. PRL 109, 186402 (2012)
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