Hydrostatic Pressure Dependence of the Superconducting and Structural Properties of MgB2

Source: arXiv


In this paper we report parallel in situ neutron powder diffraction and Tc(P) measurements versus pressure on the same MgB2 sample in a He-gas apparatus to 0.6 GPa; in addition, we present Tc(P) measurements in a helium-loaded diamond-anvil-cell to 20 GPa on the same sample. Our results are compared with those of other groups. The high precision achieved in these measurements allows a quantitative evaluation of the change in Tc as a function of the changes in structure. Our results are consistent with electron-phonon pairing in MgB2.

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Available from: D. G. Hinks, Sep 04, 2013
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    ABSTRACT: 1. Periodic structure; 2. Lattice waves; 3. Electron states; 4. Static properties of solids; 5. Electron-electron interaction; 6. Dynamics of electrons; 7. Transport properties; 8. Optical properties; 9. The fermi surface; 10. Magnetism; 11. Superconductivity; Bibliography; Index.
    American Journal of Physics 01/1979; 33(4). DOI:10.1119/1.1971507 · 0.96 Impact Factor
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    ABSTRACT: Considerable excitement has been caused recently by the discovery that the binary-boride system with stoichiometry MgB2 is superconducting at the remarkably high temperature of 39 K [J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, and J. Akimitsu, Nature 410, 63 (2001)]. This potentially opens the way to even higher-Tc values in a new family of superconductors with unexpectedly simple composition and structure. The simplicity in the electronic and crystal structures could allow the understanding of the physics of high-Tc superconductivity without the presence of the multitude of complicated features, associated with the cuprates. Synchrotron x-ray diffraction was used to measure the isothermal compressibility of MgB2, revealing a stiff tightly packed incompressible solid with only moderate bonding anisotropy between intralayer and interlayer directions. These results, combined with the pressure evolution of the superconducting transition temperature, Tc, establish its relation to the B and Mg bonding distances over a broad range of values.
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    ABSTRACT: The hydrostatic pressure effect on the newly discovered superconductor MgBâ has been determined. The transition temperature T{sub c} was found to decrease linearly at a large rate of -1.6 K/GPa, in good quantitative agreement with the ensuing calculated value of -1.4 K/GPa within the BCS framework by Loa and Syassen, using the full-potential linearized augmented plane-wave method. The relative pressure coefficient d ln T{sub c}/dp for MgBâ also falls between the known values for conventional sp and d superconductors. The observation, therefore, suggests that electron-phonon interactions play a significant role in the superconductivity of the compound.
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