Coercivity Enhancement in Exchange Biased Systems Driven by Interfacial Magnetic Frustration

Leighton, Chris; Nogués, J.; Jönsson-Åkerman, B. J.; Schuller, Iván K.

doi:10.1103/physrevlett.84.3466

Cited by 268 publications

(196 citation statements)

References 29 publications

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“…To our knowledge, the effect of disorder on the hysteresis loop loss has not yet been studied in such models. A similar effect, however, has been previously observed in a traditional exchange bias system, for which an HC increase was reported upon suppressing the net exchange bias [15]. The data in Fig.…”

Section: Hystersis Tuning Resultscontrasting

confidence: 37%

Reversible hysteresis loop tuning

Berger

Binek

Margulies

et al. 2006

Physica B: Condensed Matter

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Section: Hystersis Tuning Resultscontrasting

confidence: 37%

Reversible hysteresis loop tuning

Berger

Binek

Margulies

et al. 2006

Physica B: Condensed Matter

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“…2 Moreover, engineering fully adjustable magnetic hysteresis, 10 as well as the use of nanostructures 11 or multifunctional materials, 12 have been recently demonstrated in exchange-coupled FM/AFM systems. In addition, there are a plethora of other magnetic phenomena associated in exchange-coupled FM/AFM systems, such as coercivity enhancements, 13,14 magnetization reorientation, [15][16][17] modified antiferromagnetic spin structures, 16,18,19 and asymmetric magnetization reversal, 20,21 which are not fully understood, 2 and often manifest themselves very differently for various material combinations. Prospects for control, tailor, and enhancement of desirable effects depend upon a clear understanding of the mechanisms governing exchange bias.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2009

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Exchange bias, referred to the interaction between a ferromagnet ͑FM͒ and an antiferromagnet ͑AFM͒, is a fundamental interfacial magnetic phenomenon, which is key to current and future applications. The effect was discovered half a century ago, and it is well established that the spin structures at the FM/AFM interface play an essential role. However, currently, ad hoc phenomenological anisotropies are often postulated without microscopic justification or sufficient experimental evidence to address magnetization-reversal behavior in exchange-bias systems. We advance toward a detailed microscopic understanding of the magnetic anisotropies in exchange-bias FM/AFM systems by showing that symmetry-breaking anisotropies leave a distinct fingerprint in the asymmetry of the magnetization reversal and we demonstrate how these emerging anisotropies are correlated with the intrinsic anisotropy. Angular and vectorial resolved Kerr hysteresis loops from FM/AFM bilayers with varying degree of ferromagnetic anisotropy reveal a noncollinear anisotropy, which becomes important for ferromagnets with vanishing intrinsic anisotropy. Numerical simulations show that this anisotropy naturally arises from the inevitable spin frustration at an atomically rough FM/AFM interface. As a consequence, we show in detail how the differences observed for different materials during magnetization reversal can be understood in general terms as originating from the interplay between interfacial frustration and intrinsic anisotropies. This understanding will certainly open additional avenues to tailor future advanced magnetic materials.

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“…14 Domain wall pinning can lead to an intrinsic coercivity, altered by exchange bias. 15 These effects have been shown to modify aspects of the magnetization reversal process, but the broad correlation between antiferromagnetic coupling and positive exchange bias remains. 5 An interesting aspect is the origin of an antiferromagnetic coupling between spins at the interface when the materials themselves have ferromagnetic interactions.…”

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confidence: 99%

Positive exchange bias in ferromagnetic La0.67Sr0.33MnO3∕SrRuO3 bilayers

Rzchowski

Belenky

et al. 2004

Applied Physics Letters

132

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Epitaxial La 0.67 Sr 0.33 MnO 3 ͑LSMO͒ / SrRuO 3 ͑SRO͒ ferromagnetic bilayers have been grown on ͑001͒SrTiO 3 ͑STO͒ substrates by pulsed laser deposition with atomic layer control. We observe a shift in the magnetic hysteresis loop of the LSMO layer in the same direction as the applied biasing field (positive exchange bias). The effect is not present above the Curie temperature of the SRO layer ͑T c SRO ͒, and its magnitude increases rapidly as the temperature is lowered below T c SRO . The direction of the shift is consistent with an antiferromagnetic exchange coupling between the ferromagnetic LSMO layer and the ferromagnetic SRO layer. We propose that atomic layer charge transfer modifies the electronic state at the interface, resulting in the observed antiferromagnetic interfacial exchange coupling. © 2004 American Institute Of Physics. [DOI: 10.1063 Interactions at magnetic interfaces are central to the operation of virtually all magnetic heterostructures. When the interface is between two magnetic materials, the exchange interaction between spins at the interface is dominant, and can dramatically change the magnetic response of the overall heterostructure. Interfacial interactions in bilayers of two ferromagnets can couple the layers so strongly that both switch as a single unit. 1 In a bilayer of two ferromagnets with very different coercive fields, an "exchange spring" effect 2 can result, where the magnetization of the soft layer can reversibly "twist" with respect to the hard layer. The interfacial interaction can also shift the magnetic hysteresis loop so that it is no longer symmetric about zero applied field. This exchange bias effect, most commonly implemented by a ferromagnet/antiferromagnet interface, has been extensively used to pin the magnetization in one of the layers of a magnetic spin valve or tunnel junction.Magnetization loop shifts of a ferromagnetic film arising from interfacial exchange interactions with a "pinning layer" have been observed in many systems, including ones in which the pinning layer is ferromagnetic 3 or ferrimagnetic, 4 as well as antiferromagnetic. 5 Although the details of the interfacial spin arrangements are in some cases believed to be quite complicated, in all cases a preferred direction of the pinning layer is induced by the application of a "bias" magnetic field. In the case of an antiferromagnetic ͑AF͒ pinning layer, the dipole interaction with the applied field is usually small, and the preferred direction is determined by interaction of the AF layer with the ferromagnetic layer. An applied field can directly manipulate the magnetic orientation of ferro-and ferrimagnetic pinning layers through the dipole interaction.These interactions are characterized by the exchange field H E , the shift from zero of the magnetization loop center along the field axis. In almost all cases, this shift of the magnetization loop is opposite to the direction of applied bias field. This case is sometimes referred to as negative exchange bias. This amount of shift is the exchange ...

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Coercivity Enhancement in Exchange Biased Systems Driven by Interfacial Magnetic Frustration

Cited by 268 publications

References 29 publications

Reversible hysteresis loop tuning

Reversible hysteresis loop tuning

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

Positive exchange bias in ferromagnetic La0.67Sr0.33MnO3∕SrRuO3 bilayers

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