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Pressure effect on the superconductivity of HgBa 2 Ca 2 Cu 3 O 8+ d

Pressure effect on the superconductivity of HgBa 2 Ca 2 Cu 3 O 8+ d. 2010.11.17 Shimizu Lab. M1 KAMADA Yukihiro. Contents. Introduction The world record of the T c Pressure effect on HgBa 2 Ca 2 Cu 3 O 8+ d (previous work) T c depends on… Motivation Experiment

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Pressure effect on the superconductivity of HgBa 2 Ca 2 Cu 3 O 8+ d

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  1. Pressure effect on the superconductivity of HgBa2Ca2Cu3O8+d 2010.11.17 Shimizu Lab. M1 KAMADA Yukihiro

  2. Contents • Introduction • The world record of the Tc • Pressure effect on HgBa2Ca2Cu3O8+d (previous work) • Tc depends on… • Motivation • Experiment • About diamond-anvil cell (DAC) • High purity of the samples • The amount of the doping carriers • Method of measuring electrical resistance under high pressure with DAC • Method of cooling & determination of the pressure • Experimental result • Discussion • Summary

  3. Introduction The world record of the Tc World record of high-Tc! Tc = 164 K @ 31 GPa Its superconductivity can’t be explained with BCS theory. The mechanism of superconductivity still has many mysteries. ※ Superconductivity ・ Electrical resistance is Zero ・ Meissner effect (perfect diamagnetism)

  4. Introduction Pressure effect on HgBa2Ca2Cu3O8+d (previous work) The electrical resistivity of Hg-1223 under high pressure Pressure dependence of the Tc of Hg-series cuprate L. Gao et al., Phys. Rev. B50, 4260 (1994)

  5. Introduction Temperature optimal dope optimal dope under dope over dope quasi-gap AFM AFM SC SC 0.15 0.15～0.20 0 electron hole Tc depends on… HgBa2Cam-1CumO2m+2+d The carrier concentration m = 3 is thebest for high-Tc @ ambient pressure. d>0, supplying holes into the CuO2 layers c Pressure effect is not only changing lattice constant but also changing hole distribution between CuO2 layers etc… a a

  6. Introduction Tc depends on… La2-xSrxCuO4 Bi2Sr2Ca2Cu3O10+d Xiao-Jia Chen, Viktor V. Struzhkin, Yong Yu, Alexander F. Goncharov, Cheng-Tian Lin, Ho-kwang Mao & Russell J. Hemley, Nature 466, (2010) 950–953 F.Nakamura, J.Hori, T.Goko, Y.Uno, N.Kikugawa and T.Fujita,Journal of Low Temperature Physics, Vol. 117. Nos. 5/6, 1999

  7. Introduction Motivation • Try to make a new world record! • High purity of the sample • The amount of the doping carriers • To control the pressure condition • Higher pressure • And so on…

  8. Experiment About diamond-anvil cell (DAC) 3 cm diamond gasket pressure medium sample 6 cm diamond ※ To explain easily, this picture is the DAC which keeps the pressure by screw. In this experiment, I used the DAC which apply the pressure by gas-pressure system. Diamond Anvil Cell (DAC)

  9. Experiment High purity of the samples • Sample 1 (S1) &Sample 2 (S2) • Purity (Hg-1223 : 90%~) • Sample 1 (S1) : Tc = 134 K @ ambient pressure • To control a little under doped (annealing in a vacuum) • Sample 2 (S2) : Tc = 130 K @ ambient pressure • Not to control doping carriers The amount of the doping carriers Temperature optimal dope optimal dope under dope over dope quasi-gap AFM SC SC 0.15 0 0.15～0.20 electron hole

  10. Experiment To control the pressure condition • Sample 2 (S2) • Hydrostatic • With pressure medium (NaCl) • Non-hydrostatic • Without pressure medium

  11. Experiment Method of measuring electrical resistance under high pressure with DAC Hydrostatic (with NaCl) (Sample 1, Sample 2) AC four probe method ※ S1:pserud four probe method ※ with microscope. Insulator (c-BN powder + epoxy) Pressure marker (Ruby chip) Electrical probe (Pt foil) Electrical probe (Au wire) 1.8 GPa sample Gasket(SUS310S) Pressure Medium(NaCl) 100 mm Sample 2 300 mm

  12. Experiment Method of measuring electrical resistance under high pressure with DAC Non-hydrostatic (without pressure medium) (Sample 2) AC four probe method ※ with microscope. Electrical probe (Pt foil) Pressure marker (Ruby chip) sample 0.85 GPa Insulator (c-BN powder + epoxy) Gasket(SUS310S) 100 mm Sample 2 300 mm

  13. Experiment Method of cooling & determination of the pressure Low temperature generator : Pulse Tube refrigerator (low vibration) Camera • Pressure determination: • Ruby fluorescence method • Raman shift of diamond Measured with PC Gas type DAC Gas type DAC can change the pressure at low temperature. (DAC in the refrigerator) different type

  14. Experiment Experimental result Hydrostatic (with NaCl) (Sample 1, Sample 2) Hg-1223 (S1) with NaCl Hg-1223 (S2) with NaCl

  15. Experiment Experimental result Non-hydrostatic (without pressure medium) (Sample 2) Definition of the Tc Hg-1223 (S2) with no pressure medium Hg-1223 (S1) at 0.7 GPa Tc Tco The Tc was defined by same method of the world record

  16. Experiment Experimental result Pressure dependence of Tcabout Sample 1 (carrier controlled) and Sample 2 (non-controlled) Hg-1223 (S1 and S2) with NaCl The pressure effect of the Tc depends on the sample

  17. Experiment Experimental result Pressure dependence of Tcwith pressure medium and without pressure medium about Sample 2 ? Hg-1223 (S2) The pressure effect of the Tc depends on the way how to apply the pressure

  18. Discussion Comparing the previous work to my work Hg-1223 (S1 and S2) with NaCl Carrier density? But, can’t find any clear reasons. L. Gao et al., Phys. Rev. B50, 4260 (1994)

  19. Discussion The other discussion… Hg-1223 (S1 and S2) with NaCl The change of the Tc by applying the pressure is not continuous Phase transition?

  20. Summary • From this experiment • Can’t make the new world record… • Phase transition? • Future • 1. Higher pressure • 2. X-ray diffraction measurement • 3. Uniaxial pressure • 4. Best condition of the pressure The new world record of the Tc!?

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