1 / 23

Superconductivity in Diamond

Superconductivity in Diamond. Kitaoka Lab. Toshiyuki Tsuchida Ref.) Ekimov, et al., Nature 428, 542 (2004) Y.Takano Appl .Phys.Lett., 85,4 2004 Umezawa et al ． condmat-05503303. Contents. Introduction Physical Properties of Diamond Superconductivity in diamond

imani-key
Télécharger la présentation

Superconductivity in Diamond

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Superconductivity in Diamond Kitaoka Lab. Toshiyuki Tsuchida Ref.) Ekimov, et al., Nature 428, 542 (2004) Y.TakanoAppl .Phys.Lett., 85,4 2004 Umezawa et al．condmat-05503303

  2. Contents • Introduction • Physical Properties of Diamond • Superconductivity in diamond • Experiments • Summary

  3. Physical Properties of Diamond Covalent bonding crystal (sp3 hybrid orbital) ⇒ strong　bonding　energy hardest material chemically stable material high thermal conductivity

  4. Band structure of Diamond Band gap 5.47eV 　～ 6.3×104K good insulator Semiconducting behavior by doping carrier

  5. Carrier doping to diamond E Conduction band Eg Acceptor level Valence Band Carrier doping B3+-doping N5+-doping p-type(hole) n-type(electron) making a shallow acceptor level close to top of the valence band hole dope(acceptor) low carrier doping level →semiconducting conductivity high carrier doping level →metallic-like conductivity Electron dope(donor)

  6. Discovery of superconductivity in Diamond onset 4K offset 2.3K Ekimov, et al., Nature 428, 542 (2004)

  7. Application hardest material chemically stable material high thermal conductivity Electronic property Diamond insulator semiconductor superconductor metal B-doping hybrid electronic device

  8. onset 4K offset 2.3K Superconductivity takes place in the diamond at the interface between graphite and B4C Ekimov, et al., Nature 428, 542 (2004) Synthesis under high pressure (8～9GPa) and high temperature(2,800K)

  9. onset 4K offset 2.3K superconductor At 2.3K,the sample shows Meissner effect (perfect diamagnetism) the onset of perfect diamagnetism corresponds to zero resistance. perfect diamagnetism :完全反磁性

  10. Another approach (CVD method) Synthesis of Diamond 1. under high pressure and high temperature 2. MP-CVD method (film) CVD conditions: GAS: H2 + CH4 + TMB CH４Cont:3% TMB(B/C):2000~12000ppm Substrate: ・Si(100)* ・Single crystalline type Ib Diamond (111) and (100) Pressure: 60 Torr Microwave power:600W Depositing time:8hrs

  11. Meissnereffect Boron-doped diamond film MPCVD method onset 7K Polycrystalline offset 4K Si substrate Polycrystalline thin film (3.5 μm) on Si substrate Boron doped level ～0.53% (Carrier Density~9.4×1020cm-3)

  12. normal S.C Property of diamond film Type II superconductor Hc2(T=0K)~5.12T →ξ~100Å (ξ: coherence length) >>9Å(average length between of boron atoms) Takano et.al.Appl .Phys.Lett., 85, 4 2004

  13. (100) Homoepitaxial film bus Bustarret.et al. PRL,93,237005(2004) Tc(onset)=2.5K ΔTc is very narrow

  14. Tc(offset) vs. Boron concentration (111) epitaxial film has the higher Tc than (100) Umezawa et al．condmat-05503303

  15. superconductivity appears in the vicinity of metal-insulator transition resistivity at room temperature J.-P. Lagrange et al. D.R.M 7 (1998) 1390–1393

  16. Summary • Discovery of the superconductivity in the Boron-doped diamond by high pressure method and MPCVD method • (111) epitaxial film has the higher Tc than (100) • The superconductivity in diamond takes place in vicinity of metal-insulator transition

  17. Θ:Debye Temperature　ωD：Debye frequency κ：Thermal conductivity　C：specific heat v ：velocity l： mean free path

  18. ξ

  19. Averaged distance of B-B Boron atom is surrounded by about 6carbon atoms ⇒averaged distance of B-B ～9Å　＜＜ξ Electron can have many partners of the cooper-pair

  20. Typical character ・Zero resistivity ・Meissner effect the property of superconductivity

  21. Type-I Type-II H Hc1 Hc Hc2 Type-I and Type-II superconductor

  22. Comparing sample by different methods Yoshihiko Takano et.al.. Appl .Phys.Lett.,Vol 85,No.14,4 October 2004 Ekimov, et al., Nature 428, 542 (2004) (111)-oriented thin film ΔTc=1.7K ΔTc=3K ΔTc=Tc(onset)-Tc(offset)

  23. http://www.lcv.ne.jp/~lab72

More Related