Absence of a structural transition up to 40 GPa in MgB2 and the relevance of magnesium nonstoichiometry

Absence of a structural transition up to 40 GPa in MgB2 and the relevance of magnesium nonstoichiometry

We report measurements on MgB2 up to ∼40 GPa. Increasing pressure yields a monotonous decrease of the lattice parameters and of the c/a ratio, but no structural transition down to parameters smaller than those of AlB2. The transition superconducting temperature also decreases with temperature in a s...

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Podrobná bibliografie
Hlavní autoři: Bordet, P, Mezouar, M, Nunez-Regueiro, M, Monteverde, M, Nunez-Regueiro, MD, Rogado, N, Regan, K, Hayward, M, He, T, Loureiro, S, Cava, R
Médium: Journal article
Jazyk:English
Vydáno: 2001
Popis
Shrnutí:We report measurements on MgB2 up to ∼40 GPa. Increasing pressure yields a monotonous decrease of the lattice parameters and of the c/a ratio, but no structural transition down to parameters smaller than those of AlB2. The transition superconducting temperature also decreases with temperature in a sample-dependent way. The results are explained by an increase of the filling of the two-dimensional pxy bands with pressure, the Mg stoichiometry determining the starting position of the Fermi level. Our measurements indicate that these hole bands are the relevant ones for superconductivity.

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