1 / 15

Unconventional superconductivity in Noncentrosymmetric Heavy-Fermion superconductors

Unconventional superconductivity in Noncentrosymmetric Heavy-Fermion superconductors. E. Bauer et al, Phys. Rev. Lett . 92 . 027003 (2004) M. Yogi et al. Phys. Rev. Lett . 93 , 027003 (2004) Kitaoka Laboratory Takuya Fujii. Content. Introduction Heavy Fermion & Fermi Liquid

jalen
Download Presentation

Unconventional superconductivity in Noncentrosymmetric Heavy-Fermion superconductors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Unconventional superconductivity in Noncentrosymmetric Heavy-Fermionsuperconductors E. Bauer et al, Phys. Rev. Lett. 92. 027003 (2004) M. Yogi et al. Phys. Rev. Lett. 93, 027003 (2004) KitaokaLaboratory Takuya Fujii

  2. Content • Introduction • Heavy Fermion & Fermi Liquid • Symmetry of SC state • Inversion symmetry Experimental Data in CePt3Si Summary

  3. Introduction Heavy Fermion & Fermi Liquid RKKY interaction Kondo effect conduction electron conduction electron rare earth ion 4f-electrons are itinerant. 4f-electrons localize at atom. Magnetic order Fermi liquid state by heavy electrons

  4. Introduction Phase diagram of heavy fermion systems Non Fermi liquid Temperature (K) Magnetic order QCP Fermi Liquid 0 Pressure Unconventional SC aroundQCP mediated by magnetic fluctuations.

  5. UPt3,Sr2RuO4 BCS-SC High-TC cuprate Ce based HF-SC Introduction Pair function spin orbital

  6. CeCu2Si2 CeRhSi3 Introduction Centrosymmetric vs Noncentrosymmetric H-F SC ± Ce Cu Pt(2) Si Pt(1) CePt3Si

  7. key experimental features Noncentrosymmetric CePt3Si the first heavy fermion SC without a center of symmetry Pt(2) Pt(1) • SC ; cooper pairs formed by heavy quasiparticles (TC=0.75K) • AFM ; coexistence with SC on a microscopic scale (TN=2.2K) • High Hc2(0) • Anomalous behavior in 1/T1 of NMR Novel SC state caused by lack of inversion symmetry ?

  8. Resistivity & susceptibility TN=2.2K TC=0.75K Coexistence of SC & AFM T.Yasuda et al., J.Phys Soc.Jpn.73, 1657 (2004)

  9. Specific heat Cp C/T =γ+AT2 λ-likeanomaly at 2.2 K : onset of long range magnetic order TN=2.2K jump around 0.75K: the transition into a SC phase TC=0.75K Coexistence of SC & AFM Cp/T=γ=390 [mJ/molK2]∝m*

  10. Microscopic evidence of AFM & SC Ce Pt(2) Coexistence of SC & AFM on a microscopic scale N.Metoki ,J.Phys.: Cond. Mat16 L207 (2004)

  11. High Hc2(0) H(T)-T(K) phase diagram Hc2(0)  5T > > Hp 1T Hp =1.84＊TC HP: Pauli-Clogston limiting field H=0 H≠0 SC P-C Limit H=HP Spin-Singlet

  12. 195Pt nuclear spin-relaxation rate 1/T1 LaPt3Si ; BCS s-wave model is applicable. CePt3Si ; Small jump at Tc. However, overall T dependence is different from p-wave & BCS s-wave. LaPt3Si (La-NQR) s-wave CePt3Si (~1T) BW (full gap) p-wave Unusual T dependence of 1/T1T ⇒s+p-wave pairing SC ?

  13. Noncentrosymmetric heavy fermion Ce-compounds CeRhSi3 CePt3Si T (K) CeRhSi3: Pressured-induced SC AFM SC 0 Pt(2) Pressure Pt(1) CePt3Si

  14. High Hc2(0) Noncentrosymmetric heavy fermion Ce-compounds Novel SC states caused by lack of inversion symmetry & high HC2(0) !?

  15. Summary • The SC exists even in the AFM state in CePt3Si. • Novel cooper pairing state with the two-component order • parameter composed of spin-singlet and spin-triplet pairing • components may be realized in CePt3Si. • Noncentrosymmetric heavy fermion Ce-compounds may be • thought of as unconventional SC from the aspect of high • HC2(0).

More Related