ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The temperature and annealing effects on junctions with high (10–13 MΩ μm2) and low (25–30 kΩ μm2) resistance-area products were studied. Junction tunneling magnetoresistance (TMR) is almost unchanged and above 20% up to 200 °C. A sharp and reversible TMR decrease is observed between 200 and 220 °C and is due to the exchange loss in the pinning layer. Junction TMR increases from 22% to 26% in high resistance-area product samples (resistance decreases a factor of 2), and from 22% to 37% (resistance increases 30%) in low resistance-area product samples, upon anneal up to 200–230 °C. Rutherford backscattering (RBS) analysis of the oxygen distribution in as-deposited samples indicates oxygen asymmetry in the barrier. This asymmetry and asymmetry in barrier parameters, found in as-deposited samples, disappear after anneal at 200 °C. Two regimes for the TMR dependence on anneal are proposed. The first up to 200 °C, where TMR increases, as barrier is homogenized and polarization near the top electrode increases. The second, above 200 °C in low-resistance junctions, where TMR increase is related with barrier height increase. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.369959
