Operated by Los Alamos National Security, LLC for NNSA Electronic tuning in CeCoIn 5 : a dirty job Filip Ronning Eric Bauer Ryan Baumbach Kris Gofryk Xin.

Operated by Los Alamos National Security, LLC for NNSA

Electronic tuning in CeCoIn5:a dirty job

Filip RonningFilip Ronning

Eric BauerEric BauerRyan BaumbachRyan BaumbachKris GofrykKris GofrykXin LuXin LuM.N. Ou (Owen)M.N. Ou (Owen)Tian ShangTian ShangJoe ThompsonJoe ThompsonPaul TobashPaul TobashVladamir SidorovVladamir SidorovJianxin ZhuJianxin Zhu ((LANLLANL))

S. StoykoS. StoykoA. Mar (A. Mar (U. AlbertaU. Alberta))

Hiroshi Yasuoka (Hiroshi Yasuoka (JAEAJAEA))Tuson Park (Tuson Park (SKKUSKKU))Zach Fisk (Zach Fisk (UC IrvineUC Irvine))

Los Alamos National Lab


Outline

Motivation

“Dirt” in CeCoIn5

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

(K. Gofryk, et al. PRL 109, 186402 (2012))


Reducing Dimensionality

Increasing Bandw

idth

Incre

asing

T c10

0 x

CeIn3

CeMIn5

PuMGa5

Ce2MIn8

Tc = 0.2 K

Tc = 2.1 K

Tc = 18.5 K

Tc = 2.3 K

13 compounds in this family are

superconductors

NpPd5Al2Tc = 5 K

CeM2In7

Tc = 2.1 K


2D

3D 2D

3D

Reducing dimensionality to maximize pairing

Monthoux , Pines, & Lonzarich, Nature ‘07

Enhance matching of (q,) to Q(q,) by reducing dimensionality

CeIn3 CeCoIn5

“Active” layer

“Buffer” layer

“Active” layer

• Prototypical strongly correlated system• Quantum Criticality• Heavy Fermion• dx2-y2 SC order parameter

Monthoux & Lonzarich, PRB ‘02

CeCoIn5


Dirt as a microscope

(k)=?I. Mazin Nature ‘10

Heavy Fermion formationQuantum criticality


Anderson / Abrikosov-Gorkov theories + corollaries

Anderson’s Theorem 1959

Abrikosov-Gorkov theory 1960

• For a SC order parameter which DOES NOT change sign

• Non-magnetic impurities are weakly pair breaking

• Magnetic impurities are strongly pair breaking

• For a SC order parameter which DOES change sign• Non-magnetic impurities are strongly pair breaking

1

2

S=0

1=2 ; S=0

S≠0

; S≠0 X

1

2

S=0

1≠2 ; S=0 X


Debate on Fe-based superconductors

S. Onarii and H. Kontani, PRL ‘08Y. Nakajima, et al. PRB ‘10

• 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


Doping on the active layer: In-site Doping

R. Urbano, et al PRL ‘07

ElectronsHoles

• 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

“Active” layer

“Buffer” layer

“Active” layer

Cd, Sn for In

Pt for Co

Sn for In


What is the origin of the different doping behavior?

Cd, Hg, Sn for In

• Sn (electrons)• Cd, Hg (holes)• actual concentrations used from here on.


Ce1

Co

Ce2

X

In1

• 2 x 2 x 2 supercell• doping = 0.025

0.4

0.2

0.0

PD

OS

-5 -4 -3 -2 -1 0 1 2 3 4 5 Energy (eV)

Sn 5p In 5p

0.6

0.4

0.2

0.0

PD

OS

-5 -4 -3 -2 -1 0 1 2 3 4 5

Energy (eV)

Cd 5p In 5p

• Cd has smaller bandwidth than In• Sn has larger bandwidth than In

The role of the dopant atoms

K. Gofryk, et al PRL ‘12


Ce1

Co

Ce2

X

In1

JK = Vfc2(1/f+1/(2f+U))

30

20

10

0

PD

OS

-1.0 -0.5 0.0 0.5 1.0

Energy (eV)

Sn - doped Ce1 4f Ce2 4f

40

30

20

10

0

PD

OS

-1.0 -0.5 0.0 0.5 1.0

Energy (eV)

Cd - doped Ce1 4f Ce2 4f

• Cd locally decrease hybridization to Ce• Sn locally increases hybridization to Ce

The role of the dopant atoms


Reversible electronic tuning

• JK decreases with hole doping (Cd and Hg)

• JK increases with electron doping (Sn and Pt)

• Doping creates an inhomogeneous internal field

JK

ElectronsHoles

R. Urbano, et al PRL ‘07


Similarities in Cd and Hg tuningDFTPhase Diagrams

C. Booth, et al PRB ‘09

0.6

0.4

0.2

0.0

PD

OS

-5 -4 -3 -2 -1 0 1 2 3 4 5

Energy (eV)

Cd 5p Hg 6p In 5p

• Cd and Hg doped 115’s have nearly identical phase diagrams• DFT calculations with Cd and Hg impurity atoms give identical results


CeIn3

CeMIn5

“Active” layer

“Buffer” layer

“Active” layer

Sn for In

Pt for Co

Electron dopants to distinguish buffer layers


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 @ 0 ~ 10 cm: Can we separate pair breaking and electronic tuning effects?



Isolate pair breaking of holes using pressure

• Assume that dTc/Hg = dTc/dCd

L.D. Pham, et al. PRL ‘06

dTcmax/dCd = -5 K/Cd

• Cd doping reversible with pressure

L.D. Pham, et al. PRL ‘06


Isolate pair breaking of electrons using co-doping

dTc/dSn = -13.3 K/Sn

• Tc initially increases with Hg co-doping

• SC suppressed, but AFM QC reversible with co-doping.

dTc/dPt = -11.2 K/Pt

• Pt and Sn doping reversible with Hg doping



Comparison of pair breaking rates

dTc/dSn = -13.3 K/Sn

dTc/dPt = -11.2 K/Pt

dTc/dCd = -5 K/Cd

Rare Earths

Holes

Electrons

dTc/dR = -10 K/R

• Hole doping (AF droplets) is a significantly weaker pair breaker for superconductivity

• These are very weak suppressions, but how weak/strong is the impurity potential? Need 1/

C. Petrovic, et al. PRB ’02

J. Paglione, et al, Nat. Phys. ‘07

Hudson, et al. Nature ‘01

dTc/dZn ≈ 2 dTc/dNiCuprates:


Extracting 1/ from resistivity

1/ = ne2/m* = /

= 190 – 550 um

T [K]

pure

Pt 0.09; Hg 0.025

Sn 0.09; Hg 0.025

R.J. Ormeno, et al. PRL ’02

S. Ozcan, et al, Eur. Lett. ‘03

W. Higemoto, et al. JPSJ ‘02

d(1/)/dSn = 330 K/Sn

d(1/)/dPt = 120 K/Pt

d(1/)/dCd = 830 K/Cd


Comparison of pair breaking rates II

Impurity scattering for non-magnetic defects is remarkably weak compared with Abrikosov-Gorkov theory



R. Movshovich, M. Jaime, J. D. Thompson, C. Petrovic, Z. Fisk, P. G. Pagliuso, and J. L. Sarrao, Phys. Rev. Lett. 86,

5152 (2001).

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(2001).

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Matter 16, L13 (2004).

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Could CeCoIn5 be conventional?

NoVortex Lattice

Upper Critical Field

Specific Heat

Thermal conductivity

Neutron Resonance

Point Contact Andreev Reflection

NQR

Line Nodes!

dx2-y2!


Spectrum of weak non-magnetic pair breakingexperiment theory• Conventional SC’s• Cuprate SC’s• Fe-based 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

P. Monthoux and D. Pines, PRB ‘94• Coherence length = 5 nmR. Movshovich, et al. PRL ’01

• Multiband SC

• Cp/Tc = 4.5

• Induced moments with Cd doping

NMR: R. Urbano, et al. PRL ’07

• Spatial Inhomogeneity

E.D. Bauer, et al. PNAS ’11

C. Petrovic, et al. JPCM ’01

Thermal Conductivity

M. A. Tanatar, et al. PRL ‘05; G. Seyfarth, et al. PRL ‘08

Point Contact Spectroscopy P. Rourke, et al. PRL ‘05

• CeCoIn5


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


Electronic tuning of CeIrIn5: Cp

• Bulk Tc suppressed with doping. • QCP at slight hole doping.• Pt and Sn doping nearly identical

ElectronsHoles

T. Shang, et al unpublished


CeIrIn5: low T transport summary

• Pt and Sn doping nearly identical

• “expected” behavior for a 2D AFM QCP.

T. Shang, et al unpublished


Revisiting dimensionality in the 115 family

Monthoux , Pines, & Lonzarich, Nature ‘07

CePt2In7


Possible future direction CeIn3

LDA Wannierization Tight Binding

Impurity potentials

SC instability

Model Hamiltonians (+U)

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)

Operated by Los Alamos National Security, LLC for NNSA Electronic tuning in CeCoIn 5 : a dirty job Filip Ronning Eric Bauer Ryan Baumbach Kris Gofryk Xin.

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