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Search for superconductivity in CrB 2 under pressure

Search for superconductivity in CrB 2 under pressure. 29A13025 Shimizu Lab Kaide Naohiro. Contents. Superconductivity CrB 2 Discussion Summary & Future work. What is “superconductivity” ?. zero electrical resistance Meissner effect Josephson effect. 1 . 2 . Ｔ c = 4.2 K.

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Search for superconductivity in CrB 2 under pressure

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  1. Search for superconductivity in CrB2under pressure 29A13025 Shimizu Lab KaideNaohiro

  2. Contents • Superconductivity • CrB2 • Discussion • Summary & Future work

  3. What is “superconductivity” ? • zero electrical resistance • Meissner effect • Josephson effect 1. 2. Ｔc = 4.2 K http://www.thephysicsmill.com/2013/02/09/superconductors-and-the-valence-band/

  4. The history of superconductors http://sakaki.issp.u-tokyo.ac.jp/user/kittaka/contents/others/tc-history.html

  5. Table of AlB2 structure http://www.nishina-mf.or.jp/nkz_series/NKZ_53.pdf

  6. CrB2 1. a hexagonal layer structure (AlB2 structure) C. Michiokaet al., J. Mag. Mat. ,310 (2007) 620.

  7. CrB2 2. Itinerant antiferromagnet遍歴反強磁性 SDW(spin density wave)スピン密度波 λ= n ・ a n : integer multiple　・・・　“commensurate（整合）” n : not integer multiple　・・・　“incommensurate（不整合）”

  8. CrB2 3. TN =88 K Neel temperature (TN) : The temperature at which “paramagnetic” changes to “antiferromagnetic” antiferromagnetic paramagnetic T < TN T > TN

  9. Temperature dependence of electrical resistivity (CrB2) ・The resistivity displays a kink at the TN Ambient pressure Takahotanaka et al, journal of the Less-Common metals, 50 (1976) 15-21

  10. Motivation Apply pressure and research for superconductivity

  11. DAC (Diamond anvil cell) 3 cm 6 cm • Why use Diamond? • Hard • Transparent Diamond Anvil Cell (DAC)

  12. Setting Pt ・sample: CrB2 ・diameter of diamond: 800μm ・gasket : SUS310S ・diameter of hole : 200 μm • ・pressure medium：Glycerin ruby pressure medium (Glycerin) 800 μm Ruby Au wire SUS310S sample diamond

  13. Quantum critical point (量子臨界点) T (K) disorder order Quantum critical point P, B, x 0 P, B, x : pressure, magnetic field, chemical substitution

  14. Researching for superconductivity in CrB2around the QCP T (K) paramagnet TN antiferromagnet Quantum critical point P (GPa) 0 PC pressure-temperature phase diagram of CrB2

  15. Summary & future work ・CrB2 : AlB2 structure (MgB2), antiferromagnet ・apply pressure andsearch for superconductivity around QCP

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