Study on requirements for shielded current perpendicular to the plane spin valve heads based on dynamic read tests

Abstract

Shielded current perpendicular to the plane (CPP) spin valve heads with about 20 Gbit/in.2 dimensions were fabricated and tested both quasistatically and dynamically. Dual synthetic spin valves with 2.3 mΩ μm2 of resistivity change and area product (dRA) was used. Quasistatic tests were conducted to determine the current efficiency loss caused by the specific CPP head structure. Dynamic tests were performed to examine the flux efficiency of the readback process in the spin valve element, in order to confirm the calculation results which take into account the increase of effective anisotropy field caused by the circular sense current field. Output voltage of about 260 μV (peak to peak) was successfully obtained from the dynamic tests. Finite element modeling analysis of current distribution and temperature rise, together with degradation experiments with excessive sense current, was conducted to predict the maximum allowable current density in the 200 Gbit/in.2 dimension, where read track width and stripe height are assumed to be 100 nm. With these results, requirements of spin valve material properties (dRA, RA) and the CPP structure was predicted. Essential issues to satisfy the requirements and possible solutions are also discussed.

Current-perpendicular spin valves with high-resistivity ferromagnetic metals for ultrahigh-density magnetic recording

“…For the read sensor application of CPP spin valves [1][2][3][4], it is necessary to obtain larger DRA as mentioned above by engineering new film stacking structures and materials [7][8][9][10]. Several new spin valve structures that show larger DRA have been reported to date.…”

“…Spin valves in the current-perpendicular-to-plane (CPP) mode have been investigated extensively for read-sensor application in ultrahigh-density magnetic recording systems [1][2][3][4]. Recently, read heads utilizing a tunneling magnetoresistance (TMR) sensor that shows large output signals have been replacing those utilizing a current-inplane spin valve sensor in wide practical use.…”

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].…”

CPP-GMR technology for magnetic read heads of future high-density recording systems

“…Moreover, the CPP structure has advantages such as a short read gap and good thermal contact with the electrodes. Therefore, the CPP-GMR head is expected to replace the TMR head and enables densities exceeding 300 Gbit/in 2 [1][2][3][4].…”