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KITAOKA.LAB. M １　 MAKI SHOUTA

Charge Kondo Effect and Superconductivity in Tl -Doped PbTe Y. Matsushita,et.al . PRL 94 , 157002 (2005) T. A. Costi and V. Zlatic PRL 108, 036402 (2012 ) Hiroyasu MATSUURA and Kazumasa MIYAKE 81 (2012) 113705. KITAOKA.LAB. M １　 MAKI SHOUTA. Contents. History of Superconductivity

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KITAOKA.LAB. M １　 MAKI SHOUTA

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  1. Charge Kondo Effect andSuperconductivity in Tl-Doped PbTeY. Matsushita,et.al. PRL 94 , 157002 (2005)T. A. Costiand V. ZlaticPRL108, 036402 (2012)Hiroyasu MATSUURA and KazumasaMIYAKE 81 (2012) 113705 KITAOKA.LAB. M１　MAKISHOUTA

  2. Contents History of Superconductivity Properties of PbTe Kondo effect Valence Skipper (ex:Tl) Experimental report Summary

  3. 1900 1920 1940 1960 1980 2000 2020 Year History of Superconductivity Discovery of superconducting phenomenon 200 metal 1911 heavy fermion system high-Tc cuprate 163 Hg-Ba-Ca-Cu-O iron-based system under high pressure （ ） 150 Hg-Ba-Ca-Cu-O Heavy fermion superconductor Tl-Ba-Ca-Cu-O 1986 1979 Bi-Sr-Ca-Cu-O Transition temperature (K) 100 Y-Ba-Cu-O 77 High-Tc cuprate superconductor SmO F FeAs 50 0.9 0.11 MgB2 La-Ba-Cu-O LaO F FeAs 2006 PuCoGa5 Nb Ge Nb 0.11 0.89 Pb CeCu2Si2 NbN LaOFeP Hg NbC Iron-based high-Tc superconductor 0

  4. Properties of PbTe PbTe : Eg(4.2K)=0.119eV PbTe : Eg(300K)=0.31eV Si : Eg(300K)=1.11eV Ge : Eg(300K)=0.67eV 0.646nm NaCl structure, (space group Fm3m) Pb2+(6s26p2-2) ,Te2-(5s25p4+2) Tl-doping is hole doping to valence band

  5. SC in Tl-Doped PbTe Tc X=0

  6. X=1.3% Tl-Doped PbTe X=0.8% ρ0 X=0.4% ρ0ーρmin ρ0 X=0.3% ρmin ρ0∝X　→　impurity density X=0.2% Increase of resistivity(ρ0ーρmin) 《ｘ＞０．３》 X=0.1% X=0%

  7. Kondo effect • The Kondo effect is caused by dilute magnetic impurities in a nonmagnetic host Conduction electron Spin singlet Localized electron Fermi Sea

  8. Kondo effect • The Kondo effect is caused by dilute magnetic impurities in a nonmagnetic host Conduction electron Localized electron Fermi Sea

  9. Kondo effect • The Kondo effect is caused by dilute magnetic impurities in a nonmagnetic host Conduction electron Localized electron Fermi Sea

  10. Valence Skipper-Tl High Tl+1＜Tl+3＜＜Tl+2 Tl+2 Energy Tl+3 Tl+1 Tl1+ and Tl3+ have no magnetic moment 0e -2e Why did we expect for Kondo-like behavior? Low

  11. Ex)Kondo effect Experimental Report 1 Pb1-xTlxTe Pr1-xLaxPb3 It Isn’t based on ‘Spin-Kondo effect’ but ‘Chage Kondo effect’!!

  12. Valence Skipper -Tl En : total energy of n+ ionic state Un : effective intra-atomic Coulomb repulsion for n+ ionic state For valence skipper U(ns1) < U(ns0), U(ns2) Electron in ns1 state feels effectively intra-atomic attraction image Negative U (attractive force between electrons)

  13. X=1% 2-dimensions Negative U Attractive force between electrons Charge fluctuation causes SC? About 16Å 6.46Å

  14. Behavior of electron in Tl-Doped PbTe Negative U X>25% Attractive force between electrons -2e About 16Å 0e Charge fluctuation causes SC? 0e 6.46Å image

  15. Behavior of electron in Tl-Doped PbTe Negative U X>25% Attractive force between electrons Charge fluctuation causes SC? image

  16. Summary PbTe is semi-conductor (narrow gap ). But Pb1-xTlxTe(X>0.3%) became SC. low-temperature resistivity upturn is observed by onlyPb1-xTlxTe(X>0.3%).This behavior can be understood by ‘Charge Kondo effect’ So the theory predicts that ‘Charge Kondo effect’ relates to SC.

  17. END

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