Voltage-induced barrier-layer damage in spin-dependent tunneling junctions

The effect of a dc stress voltage on the junction resistance and magnetores istance (MR) of spin-dependent tunneling (SDT) junctions with naturally oxi dized barriers was investigated. There is a threshold voltage at which irre versible resistance change begins. Beyond this threshold, device resistance decreases gradually over a transition period prior to breakdown of the tun neling barrier. The onset voltage of irreversible resistance change is much higher than the optimum operating voltage of SDT heads having the precurso r aluminum thicknesses here investigated (5-11 Angstrom). The MR ratio decr eased with increasing stress voltage in a pattern similar to that of the ju nction resistance. (C) 2001 American Institute of Physics.