Dependence of the superconducting transition temperature of single and polycrystalline MgB2 on hydrostatic pressure
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چکیده
The dependence of Tc for MgB2 on purely hydrostatic or nearly hydrostatic pressure has been determined to 29 GPa for single-crystalline and to 32 GPa for polycrystalline samples, and found to be in good agreement. Tc decreases from 39 K at ambient pressure to 15 K at 32 GPa with an initial slope dTc=dP ’ 1:11ð2Þ K/GPa. Evidence is presented that the differing values of dTc=dP reported in the literature may result primarily from shear-stress effects in nonhydrostatic pressure media rather than from differences in the samples. Although comparison of these results with theory supports phonon-mediated superconductivity, a critical test of theory must await calculations based on the solution of the anisotropic Eliashberg equations as a function of the lattice parameters. 2002 Elsevier Science B.V. All rights reserved. PACS: 74.62.Fj; 74.70.Ad; 74.62.Dh
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تاریخ انتشار 2003