Magnetostatic effects in giant magnetoresistive spin-valve devices

Abstract

We report on magnetotransport measurements of spin valve films that have been fabricated into rectangular stripes with Au current leads. The spin valve films consisted of two magnetic NiFe layers separated by a nonmagnetic Cu layer. The top NiFe layer was magnetically pinned by a FeMn layer with an effective pinning field of 12 kA/m (150 Oe). After device fabrication, the transport properties changed dramatically as the stripe-height of the device was decreased below 1 μm. Internal demagnetizing fields and magnetostatic interactions between the magnetic layers dominated the magnetic response. These interactions change the biasing point and the linearity, and cause a decrease in sensitivity to field changes. We have developed a simple single-domain rotation model that includes magnetostatic, anisotropy, and exchange interactions to describe the magnetic behavior, from which we calculate the transport response.

Exchange bias effect in alloys and compounds

“…However, in most of the cases theories were limited to specific problems where intricate structures at the interfaces were simplified. Until now, EB effects have been exploited in several technological applications such as read head of recording devices [39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54], magnetoresistive random access memories (MRRAM) [55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76] and it has been proposed for the technological applications in stabilizing magnetization of superparamagnetic nanoparticles [77,78,79,80] or to improve coercivity and energy product of the permanent magnets [81,82,83,84].…”

The effect of cyclic annealing treatments on magnetoresistance in IrMn‐pinned top and bottom spin valves

“…For application in SV read head, the H ex should be greater than 300 Oe, and H ex and MR ratio should not be affected by temperatures of 200 °C during device production, or temperatures of 200 ℃ to 250 ℃ produced by electrostatic discharge or sensing current during device operation [10,11]. This points out on the importance of temperature dependence of the H ex .…”

Influence of nano-oxide layer on the giant magnetoresistance and exchange bias of NiMn/Co/Cu/Co spin valve sensors

“…1 In the case of spin valve read head sensors, the operating temperature can reach high values due to heating by the sensing current and electrostatic discharge. 2 Therefore, they require a high thermal stability and a sufficient exchange bias field ͑H ex ͒ even at elevated temperature. In recent years, several antiferromagnetic ͑AFM͒ materials have been used as pinning layers.…”