Shingo YONEZAWA | Unusual superconduction

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About this person

About this interview

I am now studying the unusual superconducting state of the organic superconductor (TMTSF)2ClO4, where TMTSF refers to “tetramethyl tetraselena fulvalene”, a organic molecule. This organic material is an electric conductor and becomes superconducting below 1.45 Kelvin (K). In this material, electric current easily flows to the “a” direction of the crystal structure and less conductive along the “c*” direction. Therefore, (TMTSF)2ClO4 is classified as a quasi-one-dimensional (which means nearly one dimensional) conductor. The superconducting state is unusual, in a sense that the superconductivity is stable in strong magnetic fields, over 50 kilo Oersted (kOe), when the field is applied parallel to certain crystal directions. In addition, when you plot the phase boundary curves between the superconducting state and the normal state as the temperature-field phase diagram, the shape of the curves strongly depends on the magnetic field direction. In order to clarify the origin of these unusual phenomena, I carefully studied the anisotropy of the superconducting state (i.e. field-direction dependence of the phase boundary), by precisely (Δθ ~ 0.01-0.001 degrees) controlling the field direction. This precise control has been achieved with special equipment with two orthogonal solenoids on a rotating stage. My results revealed a change in the anisotropy of the superconducting state in high field above 30 kOe. The results are plausibly explained by the scenario that a wavy (spatially modulated) superconducting state is realized in the high field regime. My next goal is to study the inside of the superconducting state and to examine whether the wavy superconducting state is really realized or not. In distant future, I'd like to discover more unusual superconducting phenomena and reveal their origins, since I believe that superconductivity is one of the most unbelievable phenomena in the nature and it itself contains a lot of interesting physics.

Interview topics

  • Unusual superconducting state in (TMTSF)2ClO4
  • Revealing hidden superconducting phenomena
  • Knowing more about the phenomenon of (TMTSF)2ClO4
  • Applying to other systems and similar materials

Figures

Fig.1. Superconducting phase boundary of (TMTSF)2ClO4(left) and Crystal structure of (TMTSF)2ClO4(right).
Fig.2. Experimental appatus of superconduction.
Fig.3. Field-angle dependance of Tc of (TMTSF)2ClO4.

Keywords

  • Superconductor
  • Ag5Pb2O6
  • (TMTSF)2ClO4

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