Large training effects in magnetic relaxation and anisotropic magnetoresistance in nanocrystalline exchange-biasedNi80Fe20/

Rotation of the Pinning Direction in the Exchange Bias Training Effect in PolycrystallineNiFe/FeMnBilayers

“…At small negative θ H−Loop , m y is nonzero and the asymmetry is prominent [6,10,11,[21][22][23], as shown in Fig. 1(b).…”

“…In the EB training effect, the exchange field H E and the coercivity H C decrease during consecutive measurements of hysteresis loops [3]. Since its first discovery, the training effect has been extensively studied, both experimentally and theoretically [3][4][5][6][7][8][9][10][11]. Very recently, the training effect and the hysteresis loop asymmetry have been found to be correlated to each other after the first magnetization reversal of the FM layer [9].…”

Training and recovery behaviors of exchange bias in FeNi/Cu/Co/FeMn spin valves at high field sweep rates

“…It is ascribed to that the spin structure of the AFM layer deviates from its equilibrium configuration and approaches another equilibrium triggered by subsequent reversals of the FM magnetization. Nowadays, studies of AFM spin dynamic behaviours with training effect in both experiments and theories have been widely reported [4][5][6][7][8][9][10][11][12][13]. Because most of studies are limited to long timescales (> 1s), by the usually quite long measurement time in magnetometry approaches, the relaxation time of AFM spin are usually reported in second timescale (∼ 10 2 − 10 4 s) [4][5][6].…”

Erase/restorable asymmetric magnetization reversal in polycrystalline ferromagnetic films

“…An important magnetization reversal property of magnetic thin films is the unusual reversal caused by complex anisotropy, such as asymmetric magnetization reversal, [1][2][3][4] multi-stepped switching, [5][6][7][8][9][10][11][12][13] etc. The asymmetric hysteresis loops are mainly observed in exchange-biased ferromagnetic-antiferromagnetic (FM/AFM) systems [14][15][16][17][18][19] and in other exchange system like exchange spring coupled bilayers. 20 The discussion and explanation has been evaded for 40 yr until the exchange bias has gained technological importance, as it pins and thus establishes a reference magnetization direction in spintronic devices.…”

“…For instance, it has been reported that while on one side of the loop the reversal takes place by magnetization rotation, on the other side it takes place by domain wall (DW) motion or incoherent rotation, and such phenomenon is often observed in certain field directions. 14,15 The asymmetric hysteresis behaviour has been investigated by using various techniques, such as domain imaging, 1,2 polarized neutron reflectometry, 16,17 magnetoresistance, 18 Kerr magnetometry, 19 etc. Different mechanisms have been proposed including higher order FM anisotropy, 4,17 dispersion of the FM or AFM anisotropy axes, 2,3 or training effect induced irreversibility, 22,23 however, a detailed understanding of this effect is still lacking.…”