Superconductivity: approaching the century jubilee

Transcription

1 SIMTECH KICK-OFF MEETING, March, 18, 2011 Superconductivity: approaching the century jubilee Andrey Varlamov Institute of Superconductivity & Innovative Materials (SPIN), Consiglio Nazionale delle Ricerche, Italy And Mediterrenian Instititute of Fundamental Physics

2 1911: discovery of superconductivity Discovered by Kamerlingh Onnes in 1911 during first low temperature measurements to liquefy helium Whilst measuring the resistivity of pure Hg he noticed that the electrical resistance dropped to zero at 4.2K In 1912 he found that the resistive state is restored in a magnetic field or at high transport currents 1913

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4 The superconducting elements L i B e N a M g B C N O F N e Transition temperatures (K) Critical magnetic fields at absolute zero (mt) K C a S c T i Fe A l S i P S C l A r V C r M n F e C o N i C u Z n G a G e A s S e B r K r (iron) T =1K R b S r Y Z r N bm o T c cr ur h P d A g C d In S n S b T e I X e GPa) (at (Niobium) C s B a L a H ftc=9k T a WR e O s Ir P t A u H g T l P b B i P o A t R n Hc=0.2T Nb Transition temperatures (K) and critical fields are generally low Metals with the highest conductivities are not superconductors The magnetic 3d elements are not superconducting...or so we thought until 2001

5 1933: Meissner-Ochsenfeld effect Ideal conductor! Ideal diamagnetic!

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7 1935: Brothers London theory H H=0

8 1937: Superfluidity of liquid He4 1978

9 Landau theory of 2nd order phase transitions Order parameter? Hint: wave function of Bose condensate (complex!) 1962

10 1950: Ginzburg-Landau Phenomenology Ψ-Theory of Superconductivity Order parameter? Hint: wave function of Bose condensate (complex!) Inserting and using the energy conservation law 2003 Thus the Gibbs free energy acquires the form

11 1950: Isotopic effect

12 1950:Electron phonon attraction

13 1957: BCS- Microscopic theory of superconductivity L 1972

14 1957: Discovery of the type II superconductivity 2003

15 U. Essmann and H. Trauble Max-Planck Institute, Stuttgart Physics Letters 24A, 526 (1967) Magneto-optical image of Vortex lattice, 2001 P.E. Goa et al. University of Oslo Supercond. Sci. Technol. 14, 729 (2001) Scanning SQUID Microscopy of half-integer vortex, 1996 J. R. Kirtley et al. IBM Thomas J. Watson Research Center Phys. Rev. Lett. 76, 1336 (1996)

16 1958: Lev Gorkov formulates elegant equations of the microscopic theory of superconductivity and demonstrates the equivalence between the microscopic BCS theory and GL phenomenology at temperatures close to the critical one.

17 1962: Josephson effect Amplitude S S 197

18 1986: Discovery of the High Temperature Superconductivity in Oxides 1987

19 1987: Nitrogen limit is overpassed YBa2Cu3O7-x: Tc=93 K

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21 MAGLEV: flying train The linear motor car experiment vehicles MLX01-01 of Central Japan Railway Company. The technology has the potential to exceed 4000 mph (6437 km/h) if deployed in an evacuated tunnel.

22 Superconducting RF cavities for colliders

23 Energy transmission

24 Transformers for railway power supply

25 Powerful superconducting magnets

26 Scientific and industrial NMR facilities 900 MHz superconductive NMR installation. It is used For pharmacological investigations of various bio-macromolecules. Yokohama City University

27 Medical NMR tomography equipment

28 Criogenic high frequency filters for wireless communications

29 Original contribution to SIMTECH Project. To be published in Europhysics Letters, full version in PRB, 2011 Quantum Fluctuations and Dynamic Clustering of Fluctuating Cooper Pairs Andrey Varlamov Institute of Superconductivity and Innovative Materials (SPIN), CNR, Italy

30 Smearing of the transition 0D superconductor

31 In-plane resistance of HTS

32 Transversal resistance of HTS

33 Nernst effect in cuprates

34 Superconducting fluctuations near Tc: qualitative picture τ GL h/ ΔE ΔE ~ k B (T Tc ) τ GL h/ ΔE h/ k BTcε T Tc 1 Tc Tc ε ln T ξgl ε Dτ GL ε ξ BCS ξgl ε ε

35 Superconducting fluctuations near Tc: paraconductivity v σ (D) AL n (D) c. p. (2e)2 τ GL ~ ε D/2 2 mc. p. 2 τ GL t 2 χ (D) AL (D) σ (2) AL e 16ε (2e) n c.p. 2 D/2 2 2 ξ GL ~ ε mc.p. c

36 Superconducting fluctuations near Tc: anomalous Maki-Thompson term t vfd t P t d 2 τ Dt d 1 g geff ωd 1 νg ln 2πT 1 ε δσ MT geff P(τ ϕ ) 2 Dτ φ e δσ MT ln 2 8ε ξ GL (ε)

37 Superconducting fluctuations near Tc: One-electron conductivity renormalization 2 2 σ νe D (ν 0 δν)e (D δd) δσ e σ DOS σ DCR 2 2 δνe D ν 0 e δd ΔE k B (T Tc ) neff n 2nc.p. 2 2nc. p.e τ imp σ DOS m 14ζ(3)e2 1 ln 4 π ε σ DCR const O ε

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39 Exact solution

40 Asymptotic regimes in the phase diagram

41 Fluctuation conductivity surface as the function of temperature and magnetic field

42 Contours of constant fluctuation conductivity.

43 Temperature dependence of the FC at different fields close to Bc2(0) and comparison to experimental data for thin films of LaSCO with Tc0 19K and Bc2(0) 15T (V.Moshchalkov et al)

44 Comparison to resistivity measurements in thin indium oxide films (A. Kapitulnik et al)

45 Comparison to resistivity measurements in thin TiN films (T. Baturina et al)

46 Comparison to resistivity measurements of the layered organic superconductor (BEDT-TTF)2Cu(NCS)2. The material has a transition temperature Tc0= 9.5 K, Bc2(0)=1.57 T (M. Kartsovnik et al)

47 Quantum fluctuations near Hc2(0): qualitative picture Close to Tc: ~ Close to Hc2(0):

48 Snapshot visible for times shorter than τqf

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