We studied the effect of different cooling-field strengths on the exchange bias by measuring the angular-dependent sheet resistance and the giant magnetoresistance of exchange-biased spin valves using a PtMn antiferromagnetic and a synthetic antiferromagnetic layer. When we annealed the spin valve at a cooling-field of 100 Oe, the exchange bias was antiparallel to the cooling-field. As we increased the cooling-field to 4000 Oe, the exchange bias direction gradually rotated and it ended up parallel to the cooling-field direction. The giant magnetoresistance also changed with the cooling-field strength. In the cooling-field range between 100 and 4000 Oe, the magnetoresistance ratios measured along the cooling-field direction were significantly reduced. However, the magnetoresistance ratios measured along the exchange bias direction increased, although still remaining smaller than those of the spin valve annealed at 100 or 4000 Oe. On the other hand, the exchange bias strength did not change significantly with the cooling-field strength.
Bibliographical noteFunding Information:
This research was supported in part by Basic Science Research Program (2010-0015924), Pioneer Research Center Program (2009-008-1530), and Grant from the Center for Nanoscale Mechatronics & Manufacturing (2010K000189) funded by the Ministry of Education, Science and Technology, Korea and the IT R&D program of MKE/KEIT (KI002189, Technology Development of 30 nm Level High Density Perpendicular STT-MRAM).
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)