Noise in NiFeCo/Cu spin valve sensors

Noise properties of FeMn/NiFeCo/Cu/NiFeCo spin valve sensors have been inve stigated for various sensor widths. The spin valve thin films were patterne d into stripes of varying widths from 2 mu m to 20 mu m. The width-to-lengt h ratio was kept constant giving a fixed resistance of about 840 Omega. The spin valve sensors have been configured to allow signal and noise measurem ents to be performed using a bridge system. Noise measurement in spin valve s with parallel anisotropy axes and cross anisotropy axes show field depend ent noise near the high sensitivity region around zero bias field. In spin valves with parallel anisotropy axes, the noise increases with decreasing s ensor width but for the cross anisotropy configuration, the noise decreases with decreasing sensor width. As the applied alternating field is increase d, the noise peaks splits into two centred at zero bias. This can be explai ned in terms of a degenerate energy state. (C) 2000 Elsevier Science S.A. A ll rights reserved.