Critical current of MgB2 microbriges

Abstract

In the present work we study the peculiarities of the critical current of MgB2 extracted from current-voltage (I-V) characteristics. The (I-V) characteristics of two parallel connected MgB2 microbriges (of 3 µm width and a diameter of the quantization loop about 3 µm) have been measured at different temperatures in the constant current regime. This circuit was made by a laser scribing (nitrogen laser with 337 nm wavelength) from a textured a-axis oriented MgB2 film grown on MgO (100) substrates with a critical temperature Tc=37,7 K.