Spin valve sensor

Equation (1) gives the unshielded spin valve sensor output voltage. 

Here, AR/R is the maximum MR signal of the spin valve sensor (reaching today 15 to 20% in specular spin valves), Rsq is the sensor square resistance (15 to 20 Q/sq), W the track width of the read element (distance between leads), h is the sensor height, / the sense current, f is the angle between the... 

Figure 6. Spin-valve sensors (a) Unshielded spin valve sensor schematics, (b) linearized transfer curve for the underbiased, and properly biased sensor, (c) experimental transfer curve for an unshielded spin valve sensor (H.Ferreira, INESC MN), and (d) shielded spin valve sensor used as a read head.

The signal to noise ratios (SNR) of spin valve sensors and MTJ sensors can be estimated from ... 

Figure 28. Photographs of spintronic biochip architectures from INESC for use in magnetic field assisted hybridization detection experiments, (a) biochip using linear spin-valve sensors (2 6 pm2) and tapered current lines, and (b) biochip using u-shaped spin-valve sensors (2.5 x 80 pm2) and u-shaped current lines...

P.P. Freitas, F. Silva, N.J. Oliveira, L.V. Melo, L. Costa, and N. Almeida Spin valve sensors. Sensors and Actuators a-Physical 81, 2-8 (2000). 

Fig. 5.3-23 Schematic illustration of an IBM GMR spin valve sensor used in read heads. M and M2 are magnetizations,and 0i and 62 are angles from the longitudinal direction. The read head moves perpendicular to the xy plane. (After [3.102])...

Semiconductor nanoparticles and QDs are widely used in various fields such as luminescent biolabels [150-152] and have been demonstrated as components in regenerative solar cells [153-155], optical gain devices [24] and electroluminescent devices [23, 156, 157]. DMS have applications in spin-based electronics technologies, or spintronics [158-161]. Spintronic devices such as magnetic-optic switches, magnetic sensors, spin valve transistors and spin LEDs can be activated by implanting ferromagnetic Mn, Ni, Co and Cr in semiconductors [162-165]. Some of the applications of semiconductor nanoparticles or QDs have been explained in this section. 

Fig. 5. 3-32 Schematic illustration of an MR read head. A spin valve ( aU-metal or MTJ) is used as an ultrasensitive sensor for the very low magnetic field strength generated by the small magnetic domains (bits). When a weak magnetic field, such as from a bit on a hard disk, passes beneath the read head, the magnetic orientation of the free layer changes its direction relative to the pinned layer, generating a change in electrical resistance due to the GMR effect. (After [3.106])...

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