Superconductivity in magnesium diboride thin films

摘要

Mg-B thin films were grown in situ on (100) SrTiO_3 substrates by pulsed laser deposition. Targets pressed from a commercial MgB_2 powder had a superconducting transition temperature of 37 K. Films were characterized by atomic force microscopy and susceptibility measurements. First samples showed superconducting onset at 30 K and became superconducting at about 20 K. Films were patterned into microbridges 4-100 μm wide by Ar ion beam milling. Films had large contact resistances, of the order of 500 Ωcm~2 in the temperature range 4.2-300 K.