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Hall effect of Iodine in High Pressure

Hall effect of Iodine in High Pressure. Shimizu Lab M1 Yuma Hayashi. Contents. Introduction Motivation Experiments Hall Effect Results Summary Next plan. Introduction. room –temperature superconductor?. http://www.cqst.osaka-u.ac.jp. S tructural phase transition of iodine.

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Hall effect of Iodine in High Pressure

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  1. Hall effect of Iodine in High Pressure Shimizu Lab M1Yuma Hayashi

  2. Contents • Introduction • Motivation • Experiments Hall Effect • Results • Summary • Next plan

  3. Introduction room –temperature superconductor? http://www.cqst.osaka-u.ac.jp

  4. Structural phase transition of iodine Highpressure Ambient pressure I phase • molecular • insulator ・atomic • ・metal Molecular dissociation @21GPa Y. Fujii, K. Hase, N. Hamaya, Y. Ohishi, A. Onodera, O. Shimomura, and K. Takemura, Phys. Rev. Lett. 58, 796 (1987). B. Albert, K. Schmit, Z. Anorg. Allg. Chem. 627, 809 (2001).

  5. N. Sakai, K. Takemura and K. Tsuji, J. Phys.Soc. Jpn. 51, 1811 (1982). Electrical property of Iodine in high pressure The temperature dependence of electrical resistance of iodine becomes positive at 14-16 GPa, indicating insulator to metal transition

  6. Superconductivity of iodine Iodine becomes superconductor in phase Ⅱ at about 1.2 K. K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853 (1992).

  7. Phase diagram of iodine Monatomic phase Moleculardissociation Molecular phase (Ⅰ) Crystal structure R.T. (Ⅱ) (Ⅲ) (Ⅳ) Electrical characteristic metal Insulator Superconductor 43 55 0 16 21 Pressure [GPa]

  8. Motivation • Identify the carrier of iodine under pressure. • Explain the pressure dependence of Tc by observation of Hall effect.

  9. Hall effect z Ex: carrier is ‘hole’ Ⅰ x B y VH F + + + + + F: Lorentz force VH： Hall voltage

  10. ω z eE Ⅰ F d x B y VH L RH＝ VH＝RH + （ RH ：Hall coefficient） + + + + + （ n：carrier density）

  11. V- V+ I- I+ B V0 [top view] Diamond anvil cell (DAC)

  12. Results V+ V- I- I+ B V0 [top view] ・The carrier of iodine is ‘hole’.

  13. RH＝ T. Yamauchi et al., J. Phys. Soc. Jpn., 63, 3207-3209 (1994). Tc∝θDexp[-1/N(0)V] （ n：carrier density）

  14. Summary ・The carrier of metallic iodine is hole. ・In phase Ⅱ, the pressure dependence of Tc is not related to the carrier density. ・Tc in phase Ⅰis not observed because the density of carriers is too small to induce the superconducting transition .

  15. Ⅴ phase between Ⅰ and Ⅱ phaseat 24-25 GPa Monoatomicphase Molecular phase (Ⅰ) Crystal structure (Ⅴ) R.T. (Ⅱ) (Ⅲ) (Ⅳ) ・incommensuratestructure ・metal K. Takemura et al., Nature 423, 971 (2003).

  16. Next plan We may have not observed the Hall effect of iodine in phase Ⅴ. I will try to perform careful observation of the Hall effect of iodine in phase Ⅴ.

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