1. 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 Lu M.N. Ou (Owen) Tian Shang Joe Thompson Paul Tobash Vladamir Sidorov Jianxin Zhu (LANL) (LANL) S. Stoyko A. Mar (U. Alberta) Hiroshi Yasuoka (JAEA) Tuson Park (SKKU) Zach Fisk (UC Irvine) Los Alamos National Lab

2. Operated by Los Alamos National Security, LLC for NNSA Outline Motivation Dirt in CeCoIn 5 Dopants locally modify hybridization Transition metal layers are NOT charge reservoir layers. (Sn vs. Pt doping) Weak pair breaking effects in CeCoIn 5 and quantifying it. Normal state transport Conclusions (K. Gofryk, et al. PRL 109, 186402 (2012))

3. Operated by Los Alamos National Security, LLC for NNSA Reducing Dimensionality Increasing Bandwidth Increasing T c 100 x CeIn 3 CeMIn 5 PuMGa 5 Ce 2 MIn 8 T c = 0.2 K T c = 2.1 K T c = 18.5 K T c = 2.3 K 13 compounds in this family are superconductors NpPd 5 Al 2 T c = 5 K CeM 2 In 7 T c = 2.1 K

4. Operated by Los Alamos National Security, LLC for NNSA 2D 3D 2D 3D Reducing dimensionality to maximize pairing Monthoux, Pines, & Lonzarich, Nature 07 Enhance matching of (q, ) to Q (q, ) by reducing dimensionality CeIn 3 CeCoIn 5 Active layer Buffer layer Active layer Prototypical strongly correlated system Quantum Criticality Heavy Fermion d x2-y2 SC order parameter Monthoux & Lonzarich, PRB 02 CeCoIn 5

5. Operated by Los Alamos National Security, LLC for NNSA Dirt as a microscope (k)=? I. Mazin Nature 10 Heavy Fermion formation Quantum criticality

6. Operated by Los Alamos National Security, LLC for NNSA Anderson / Abrikosov-Gorkov theories + corollaries Andersons 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 S0 ; S0 X 1 2 S=0 1 2 ; S=0 X

7. Operated by Los Alamos National Security, LLC for NNSA Debate on Fe-based superconductors S. Onarii and H. Kontani, PRL 08 Y. 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

8. Operated by Los Alamos National Security, LLC for NNSA 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 CeMIn 5 Active layer Buffer layer Active layer Cd, Sn for In Pt for Co Sn for In

9. Operated by Los Alamos National Security, LLC for NNSA 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.

10. Operated by Los Alamos National Security, LLC for NNSA Ce1 Co Ce2 X In1 2 x 2 x 2 supercell doping = 0.025 Cd has smaller bandwidth than In Sn has larger bandwidth than In The role of the dopant atoms K. Gofryk, et al PRL 12

11. Operated by Los Alamos National Security, LLC for NNSA Ce1 Co Ce2 X In1 J K = V fc 2 ( 1 / f + 1 / (2 f + U) ) Cd locally decrease hybridization to Ce Sn locally increases hybridization to Ce The role of the dopant atoms

12. Operated by Los Alamos National Security, LLC for NNSA Reversible electronic tuning J K decreases with hole doping (Cd and Hg) J K increases with electron doping (Sn and Pt) Doping creates an inhomogeneous internal field J K ElectronsHoles R. Urbano, et al PRL 07

13. Operated by Los Alamos National Security, LLC for NNSA Similarities in Cd and Hg tuning DFTPhase Diagrams C. Booth, et al PRB 09 Cd and Hg doped 115s have nearly identical phase diagrams DFT calculations with Cd and Hg impurity atoms give identical results

14. Operated by Los Alamos National Security, LLC for NNSA CeIn 3 CeMIn 5 Active layer Buffer layer Active layer Sn for In Pt for Co Electron dopants to distinguish buffer layers

15. Operated by Los Alamos National Security, LLC for NNSA Sn vs Pt T c suppression Impurity potential nearly identical for Sn and Pt dopants. Implies screening length unit cell. No such thing as buffer layers in the 115s. T c 0 @ 0 ~ 10 cm: Can we separate pair breaking and electronic tuning effects? K. Gofryk, et al PRL 12

16. Operated by Los Alamos National Security, LLC for NNSA Isolate pair breaking of holes using pressure Assume that dT c /Hg = dT c /dCd L.D. Pham, et al. PRL 06 dT c max /dCd = -5 K/Cd Cd doping reversible with pressure L.D. Pham, et al. PRL 06

17. Operated by Los Alamos National Security, LLC for NNSA Isolate pair breaking of electrons using co-doping dT c /dSn = -13.3 K/Sn Tc initially increases with Hg co-doping SC suppressed, but AFM QC reversible with co- doping. dT c /dPt = -11.2 K/Pt Pt and Sn doping reversible with Hg doping K. Gofryk, et al PRL 12

18. Operated by Los Alamos National Security, LLC for NNSA Comparison of pair breaking rates dT c /dSn = -13.3 K/Sn dT c /dPt = -11.2 K/Pt dT c /dCd = -5 K/Cd Rare Earths Holes Electrons dT c /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 dT c /dZn 2 dT c /dNi Cuprates:

19. Operated by Los Alamos National Security, LLC for NNSA Extracting 1/ from resistivity 1/ = ne 2 /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

20. Operated by Los Alamos National Security, LLC for NNSA 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

21. Operated by Los Alamos National Security, LLC for NNSA 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 (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). [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). [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). [16] C. Stock, C. Broholm, J. Hudis, H. J. Kang, and C. Petrovic, Phys. Rev. Lett. 100, 087001 (2008). Could CeCoIn 5 be conventional? No Vortex Lattice Upper Critical Field Specific Heat Thermal conductivity Neutron Resonance Point Contact Andreev Reflection NQR Line Nodes! d x2-y2 !

22. Operated by Los Alamos National Security, LLC for NNSA Spectrum of weak non-magnetic pair breaking experimenttheory Conventional SCs Cuprate SCs Fe-based SCs 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 nm R. Movshovich, et al. PRL 01 Multiband SC C p / T c = 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 CeCoIn 5

23. Operated by Los Alamos National Security, LLC for NNSA Electronic tuning of CeCoIn 5 : transport Sublinear transport unusual QCP Mirrored by C p data (Fisher-Langer) The influence of disorder on the normal state is still poorly understood. CeIrIn 5 has a more expected response to disorder

24. Operated by Los Alamos National Security, LLC for NNSA Electronic tuning of CeIrIn 5 : C p Bulk T c suppressed with doping. QCP at slight hole doping. Pt and Sn doping nearly identical ElectronsHoles T. Shang, et al unpublished

25. Operated by Los Alamos National Security, LLC for NNSA CeIrIn 5 : low T transport summary Pt and Sn doping nearly identical expected behavior for a 2D AFM QCP. T. Shang, et al unpublished

26. Operated by Los Alamos National Security, LLC for NNSA Revisiting dimensionality in the 115 family Monthoux, Pines, & Lonzarich, Nature 07 CePt 2 In 7

27. Operated by Los Alamos National Security, LLC for NNSA Possible future direction CeIn 3 LDAWannierizationTight Binding Impurity potentials SC instability Model Hamiltonians (+U) Doniach Diagram

28. Operated by Los Alamos National Security, LLC for NNSA Conclusions Doping CeMIn 5 has both a pair breaking effect and an electronic tuning effect both of which influence T c. Similarity of Pt and Sn doping implies no buffer layer in CeMIn 5. 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)