High temperature magnetoresistance in (Co, CoFe and NiFe)/Cu/CoFe/IrMn spin-valves

The MR characteristics of temperature variations ranging from room temperat ure to 570 K for IrMn spin-valves which consist of free layer Co, CoFe and NiFe were studied. Co-SV had the highest MR value in all temperature ranges among them and even at 510 K the MR ratio held more than half of room temp erature value. Whereas CoFe-SV had a slightly higher MR than NiFe-SV below 450K. above 450K CoFe-SV showed a lower MR ratio than NiFe-SV. MR loops of large coercivity such as CoFe free magnetic layer collapsed in the lower el evated temperature compared to NiFe and Co. Small coercivity of the free ma gnetic layer would be preferable to spin-valves. (C) 2001 Elsevier Science B.V. All rights reserved.