Domain structure and magnetization reversal of antiferromagnetically coupled perpendicular anisotropy films

Hellwig, Olav; Berger, Andreas; Kortright, Jeffrey B.; Fullerton, Eric E.

doi:10.1016/j.jmmm.2007.04.035

Cited by 262 publications

(238 citation statements)

References 116 publications

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“…The first step corresponds to the reversal of the center Co/Pt stack, as resolved by depth sensitive Kerr measurements. 32 Due to the small number of repeats (X=5), dipolar fields are not strong enough to trigger vertically synchronized stripe domain formation throughout all three stacks of the film. At the second reversal step, the entire magnetic configuration inverts, i.e., the two outer Co/Pt stacks switch to negative saturation while the center stack switches back to positive saturation due to the strong AF interlayer exchange coupling.…”

Section: Laterally Correlated Reversalmentioning

confidence: 99%

Temperature-dependent magnetization reversal in(Co∕Pt)∕Rumultilayers

et al. 2008

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TitleTemperature-dependent magnetization reversal in (Co/Pt)/Ru multilayers AbstractAntiferromagnetically coupled (Co/Pt)/Ru multilayers with perpendicular anisotropy have been shown to exhibit both vertically and laterally correlated magnetization reversal modes.In this work the magnetization reversal of a multilayer film whose layer thicknesses have been tuned to be at the phase boundary between the two reversal modes has been investigated as a function of temperature using the first-order reversal curve (FORC) method. At high temperatures reversal via vertically correlated stripe domains throughout the film thickness is observed, similar to that in Co/Pt films without the Ru spacers. At low temperatures antiferromagnetic (AF) interlayer exchange coupling dominates, and laterally correlated reversal is observed with an AF coupled remanent state. Under magnetic field cycling, dipolar fields can transform the sample back into a vertically correlated domain state, thus leading to an exotic behavior with FORC's existing outside the major hysteresis loop. Calculations show that the laterally correlated reversal mode is indeed slightly more stable, and the crossover to vertically correlated reversal can be induced by temperature as well as magnetic field.

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Section: Laterally Correlated Reversalmentioning

confidence: 99%

Temperature-dependent magnetization reversal in(Co∕Pt)∕Rumultilayers

et al. 2008

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“…EB was also studied in all coupled FM films with in-plane magnetized ferromagnets acting as pinning layers 21,22 . However, for applications, perpendicular uniaxial and unidirectional anisotropies are more desirable owing to a larger thermal stability of encoded information 23 . For instance, antiferromagnets in contact to ferromagnets with perpendicular anisotropy like Co/Pt multilayers and CoPt 3 layers have been shown to exhibit EB and all other macroscopic behaviour of EB systems, like training effect, enhanced coercivity and blocking temperature for the onset of the EB [23][24][25][26] .…”

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confidence: 99%

“…However, for applications, perpendicular uniaxial and unidirectional anisotropies are more desirable owing to a larger thermal stability of encoded information 23 . For instance, antiferromagnets in contact to ferromagnets with perpendicular anisotropy like Co/Pt multilayers and CoPt 3 layers have been shown to exhibit EB and all other macroscopic behaviour of EB systems, like training effect, enhanced coercivity and blocking temperature for the onset of the EB [23][24][25][26] . More recently, the perpendicular EB (PEB) was demonstrated in a novel exchange-coupled system Sm 1 − 0.028 Gd 0.028 Al 2 /SmAl 2 based on the zero magnetization ferromagnet Sm 1 − 0.028 Gd 0.028 Al 2 as the pinning layer 27 .…”

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confidence: 99%

Perpendicular exchange bias in ferrimagnetic spin valves

et al. 2012

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The exchange bias effect refers to the shift of the hysteresis loop of a ferromagnet in direct contact to an antiferromagnet. For applications in spintronics a robust and tunable exchange bias is required. Here we show experimental evidence for a perpendicular exchange bias in a prototypical ferrimagnetic spin valve consisting of DyCo 5 /Ta/Fe 76 Gd 24 , where the DyCo 5 alloy has the role of a hard ferrimagnet and Fe 76 Gd 24 is a soft ferrimagnet. Taking advantage of the tunability of the exchange coupling between the ferrimagnetic layers by means of thickness variation of an interlayer spacer, we demonstrate that perpendicular unidirectional anisotropy can be induced with desirable absolute values at room temperature, without making use of a field-cooling procedure. moreover, the shift of the hysteresis loop can be reversed with relatively low magnetic fields of several hundred oersteds. This flexibility in controlling a robust perpendicular exchange bias at room temperature may be of crucial importance for applications.

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“…Magnetic fringe fields induced by a ferromagnet are mainly determined by the magnetic domain structure. For a film with magnetic anisotropy, the domain structure is highly anisotropic and hysteretic and it can be controlled by engineering the magnetic media [29,30]. The strength and the spatial-correlation length of fringe fields from a ferromagnet also depend sensitively on the distance from the ferromanget.…”

Section: Fringe-field-induced Magnetoresistance and Magnetoelectrolummentioning

confidence: 99%