Magnetic relaxation of exchange biasedPt∕Comultilayers studied by time-resolved Kerr microscopy

Abstract

Magnetization relaxation of exchange biased (Pt/Co)5/Pt/IrMn multilayers with perpendicular anisotropy was investigated by time-resolved Kerr microscopy. Magnetization reversal occurs by nucleation and domain wall propagation for both descending and ascending applied fields, but a much larger nucleation density is observed for the descending branch, where the field is applied antiparallel to the exchange bias field direction. These results can be explained by taking into account the presence of local inhomogeneities of the exchange bias field.

Emergence of noncollinear anisotropies from interfacial magnetic frustration in exchange-bias systems

“…In general, rotation processes are more relevant in one branch of the hysteresis loop, in which a larger density of domains during irreversible domain nucleation processes is also observed. 25,28,29,35,36 For some systems, rounded transitions in M ʈ and larger M Ќ values are found in the descending branch, 20,21,[25][26][27][28][34][35][36] where the field is applied parallel to the exchange-bias direction, while other systems display the opposite behavior. [21][22][23][24][25][29][30][31][32][33] Our results indicate that this discrepancy is related to the difference between a collinear and a noncollinear anisotropy case.…”

“…Asymmetries in the magnetization reversal have been observed for many FM/AFM systems with both in-plane [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and perpendicular 35,36 anisotropy for the FM layer. In general, rotation processes are more relevant in one branch of the hysteresis loop, in which a larger density of domains during irreversible domain nucleation processes is also observed.…”

Magnetization reversal, asymmetry, and role of uncompensated spins in perpendicular exchange coupled systems

“…16 This asymmetric behavior has also been shown by Kerr microscopy measurements in perpendicular exchange-biased ͓Pt/ Co͔ n / IrMn films. 10 In summary, we have investigated the microscopic magnetization reversal behavior of room temperature perpendicular exchange coupled ͓Pt/ Co͔ n / FeMn films by means of SXRMS. The element selectivity reveals a parallel alignment between the F and the uncompensated AF moments, as well as the influence of the pinned ͑unpinned͒ uncompensated AF spins on H E ͑⌬H C ͒.…”

“…2,4 Future advances are promoted by the recent observation of perpendicular exchange-coupling effects in several F/AF systems below [5][6][7] and above room temperature. [8][9][10] Most of the studies on F/AF systems have focused on in-plane magnetization systems. Recently, it has been found that the pinned and unpinned uncompensated AF spins at the interface are correlated with H E ͑Ref.…”

Asymmetric magnetization reversal and its dual origin in Co/FeMn out-of-plane induced exchanged bias systems

“…It has been revealed that the forward and backward branches of the magnetization reversal are performed in different modes, such as the separated ways of magnetic moment rotation [5][6][7][8], the distinct nucleation sites and abilities of the inverse domain [9][10][11][12][13][14][15][16][17][18], and the unsymmetrical training and recovering effect of the pinning of the UCAS [3,[19][20][21][22]. Most AMRBs, except for the loop shift, have their particular features in the specific EB systems, which strongly depends on the structure [1,4,23,24] and measuring methods [4,[9][10][11][25][26][27][28].…”