Magnetic properties of spin valves having extremely thin underlayers

Abstract

Magnetic properties of spin valve elements having Mo(N) and Ta(N) underlayers were studied by varying their thickness. Spin valve structure was Si/SiO2/Underlayer(tÅ)/NiFe(21 or 42Å)/CoFe(28Å)/ Cu(22Å;)/CoFe(18Å)/IrMn(65Å)/Ta(25Å). Spin valve elements having exteremely thin Mo(N) and Ta(N) underlayers showed high MR ratio of about 7 - 8 %. Annealing of such spin valve elements having underlayer thickness of 7 to 8 A showed comparable behavior with the spin valve elements with thicker (35Å) underlayer, which can be utilized to reduce overall device thickness. Also, it was found that Mo(N) underlayers for spin valve elements may be used as diffusion barriers between Si substrate and ensuing active spin valve layers, simultaneously. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.