In-plane magnetic anisotropies in Ni/FeMn and Ni90Fe10/FeMn exchange biased bilayers

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

“…A similar noncollinear configuration has already been used to model recent experimental observations in exchange-bias systems. [22][23][24][25] In our case, this is unambiguously deduced from the angular dependence of in-plane angle-resolved hysteresis loops, their asymmetry, and a fit to a modified Stoner-Wohlfarth ͑SW͒ model. Additional numerical simulations show that the new anisotropy naturally arises from the inevitable spin frustration at the atomically rough FM/AFM interface, which becomes important for vanishing FM anisotropy.…”

“…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. Moreover, the nature of the anisotropy can be unambiguously deduced from the angular dependence of the hysteresis loops.…”

“…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.…”

“…The asymmetric-shape behavior observed for Co/IrMn is well reproduced by considering collinear anisotropies. Surprisingly, although the field cooling was performed with the external field oriented parallel to the easy axis of the original FeNi uniaxial anisotropy, noncollinear anisotropies [22][23][24][25] with a significant misalignment ͑ = −20°͒ have to be considered to reproduce the hysteresis loops obtained for the FeNi/IrMn bilayers.…”

Highly asymmetric magnetic behavior in exchange biased systems induced by noncollinear field cooling

“…In general, the interfacial exchange coupling effects depend on the strength of the anisotropies 5 as well as their relative orientation, 6 exhibiting a complex phase diagram of different reversal modes. 5,6,[11][12][13][14][15] In fact, the relative orientation between the intrinsic FM anisotropy and the induced interfacial unidirectional anisotropy can be controlled by different FC procedures, varying both strength, 7,8 FC angle, 6,9,10 and/or interfacial magnetic frustration. 14,15 In this letter we present a detailed study on the magnetization reversal of FM/AFM systems with a noncollinear uniaxial, K U , and unidirectional, K E , anisotropy configuration.…”