Investigation of a superconducting Mg1-xAlxB2 system by tunneling and microjunction (Andreev) spectroscopies

A detailed investigation of multiband superconductivity in the Mg1 - xAlxB2 system was carried out by the methods of tunneling and Andreev spectroscopy. Temperature dependences of the superconducting gaps and their variation upon an increase in the degree of disorder and the Al concentration were studied. It is shown that the experimentally observed dependences cannot be explained in detail within the framework of the presently available microscopic theories. (C) 2004 MAIK Nauka / Interperiodica.