High-sensitive hysteresisless spin valve with a composite free layer

• Published in: Physics of metals and metallography Vol. 113; no. 4; pp. 341 - 348
• Main Authors: Ustinov, V. V., Milyaev, M. A., Naumova, L. I., Proglyado, V. V., Bannikova, N. S., Krinitsina, T. P.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-04-2012; Springer; Springer Nature B.V
• Subjects: Alloys; Antiferromagnetism; Chemistry and Materials Science; Electrical and Magnetic Properties; Hysteresis; Magnetic fields; Magnetization; Magnetoresistance; Magnetoresistivity; Manganese base alloys; Materials Science; Metallic Materials; Nanostructure; Spin valves; Tantalum; Valves; Mn; magnetron deposition; small hysteresis of the free layer; Ir; spin valve; multilayer nanostructures; giant magnetoresistance; Fe
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X12040151

Method of dc magnetron deposition has been used to prepare metallic nanostructures of the (Si, Al
2
O
3
, glass)/Ta/[NiFe/CoFe]/Cu/CoFe/(FeMn, MnIr)/Ta spin-valve type with a composite “free layer” Ni
80
Fe
20
/Co
90
Fe
10
. A three-stage method of decreasing hysteresis of the free layer has been suggested. The dependence of the magnitude of the giant magnetoresistance and hysteresis has been investigated depending on the angle between the direction of the easy magnetization axis of the free layer and the direction of the applied magnetic field in the plane of layers. It is shown that in the spin valves studied the hysteresis can be reduced to a few tenths of an oersted at the magnitude of the magnetoresistance more than 8%. In the case of a spin valve with an antiferromagnet Fe
50
Mn
50
the magnetoresistive sensitivity in the range of the hysteresisless variation of the magnetoresistance was equal to 1%/Oe, whereas the maximum sensitivity in the presence of a hysteresis exceeded 6%/Oe. A greater sensitivity (2.5%/Oe) at the magnitude of the free-layer hysteresis of 0.6 Oe was obtained for spin valves on the basis of the antiferromagnetic Mn
75
Ir
25
alloy. For them, the maximum magnetoresistance was equal to 11.6%.