Nature of magnetization reversal in exchange-coupled polycrystalline NiO-Co bilayers

Magnetic reversal of perpendicularly-biased Co/Pt multilayers

“…We find that there are clear differences in the nucleation properties of the reverse domains of the ascending and descending 9 branches of the loops in agreement with Refs. 8 and 9.…”

“…Research has recently focused on the role of exchange bias on the reversal behavior of F/AF bilayers. [5][6][7][8][9] In particular, it has been observed that in addition to shifting the hysteresis loop and enhancing the coercivity, exchange bias can also lead to asymmetrical loop shapes. This behavior has recently been related to differences in the magnetic reversal mode during the ascending and descending branches of the hysteresis loop.…”

“…This behavior has recently been related to differences in the magnetic reversal mode during the ascending and descending branches of the hysteresis loop. [5][6][7][8][9] Asymmetric reversal appears to be a rather general property and may prove crucial to understanding many of the physical phenomena observed in exchange-biased systems.…”

“…The specific local domain structure, however, could differ with field cycling and would require magnetic imaging 9,17 or coherent scattering 18 to determine the specific microscopic reversal pathway. These results are in contrast to those observed in Ref.…”

“…Local variations in the exchange bias have been postulated by random field theory 19 and have also been experimentally observed in magnetic imaging of exchange-bias bilayers. 9,17 If present, the stronger biased regions would only effect the nucleation on the ascending branch of the hysteresis loop. For the present samples, these initially nucleated domains in the ascending branch are not sufficient to initiate a complete reversal and remain pinned.…”