Hybrid domain walls and antiferromagnetic domains in exchange-coupled ferromagnet/antiferromagnet bilayers

Chien, C. L.; Gornakov, V. S.; Никитенко, В. И.; Shapiro, Alexander J.; Shull, Robert D.

doi:10.1103/physrevb.68.014418

Cited by 68 publications

(42 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Such an uncompensated AF spin has both parallel and antiparallel AF neighbors, and, therefore, is in a frustrated state. Similar configurations may exist if other mechanisms are involved in the exchange anisotropy, such as spin-flop coupling [18,19], hybrid F-AF domain walls [20] or partial AF domains [21]. The frustrated state of the interfacial AF spins in combination with the reduced AF coordination number at the interface leads to the situation, when T N int is less than T N , and the interfacial AF spins can be reoriented by an external field above this temperature, and below T N [22].…”

Section: Figmentioning

confidence: 99%

Characteristic temperatures of exchange biased systems

Dobrynin

Prozorov

2007

Journal of Applied Physics

View full text Add to dashboard Cite

Characteristic temperatures in ferromagnetic -antiferromagnetic exchange biased systems are analyzed. In addition to usual blocking temperature of exchange bias TB, and the Néel temperature of an antiferromagnet TN , the inducing temperature T ind , i.e., the temperature, at which the direction of exchange anisotropy is established, has been recently proposed. We demonstrate that this temperature is in general case different from TB and TN . Physics and experimental approaches to measure the inducing temperature are discussed. Measurements of T ind , in addition to TB, and TN , provide important information about exchange interactions in ferromagnetic -antiferromagnetic heterostructures.PACS numbers: 75.30. Gw, 75.70.Cn, 75.30.Et, 75.50.Ee Exchange anisotropy appears in hybrid ferromagnetic (F) -antiferromagnetic (AF) systems due to exchange interactions at the F-AF interface [1]. The interfacial exchange creates an additional energy barrier, which F magnetic moments have to overcome during the magnetization reversal. The exchange anisotropy is unidirectional and shows up as a horizontal shift of the magnetic hysteresis loop after field cooling, and the exchange bias field is determined as the value to which the center of the hysteresis loop is shifted with respect to the zero field [2]. This assumes that the AF structure stays stable, which is valid unless the total AF magnetocrystalline anisotropy is too low, when AF spins rotate coherently with F spins, and the exchange bias vanishes [3,4,5]. The loop is normally shifted in the direction opposite to the cooling field, which indicates that the interfacial exchange coupling is ferromagnetic, i.e., it favors parallel orientation of the interfacial F and AF spins. The case of "positive" loop shifts, which may assume antiferromagnetic coupling at the F-AF interface (favoring antiparallel alignment of the interfacial F and AF spins), was described by Nogués et al. [6,7].It is a "common knowledge" that the exchange anisotropy is established when field cooling a F-AF system through the Néel temperature T N of the antiferromagnet [8,9]. The blocking temperature of exchange bias T B is the temperature, at which exchange bias disappears. It has been recently demonstrated that the direction of exchange anisotropy can be established at a temperature larger than T B , which is determined as exchange bias inducing temperature T ind [10].The procedure of measuring T ind is as follows. At first the sample is field cooled in a "negative" field −H F C from temperature T M (T M > T N ), to a certain temperature T switch , where the sign of the cooling field is changing. The further cooling to the temperature T m * Electronic address: dobrynin@ameslab. gov FIG. 1: Fig. 1. Exchange bias field H eb , measured at temperature Tm as a function of temperature T switch , at which the direction of the cooling field is changed from −HF C to +HF C . The temperature is scanning from TM down to Tm. In case of T ind < T switch < TM the exchange bias is negative (−Hm), since it's induced ...

show abstract

Section: Figmentioning

confidence: 99%

Characteristic temperatures of exchange biased systems

Dobrynin

Prozorov

2007

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…[16] Experimentally, it is not apparent to detect the influence of AFM spin orientation on training effect. For Co/CoO system, several techniques have been applied to study AFM domains [17], and applied in-plane magnetic field perpendicular to the cooling field largely restores the untrained state [3]. So, the reappearance of untrained state will promote us obtain the training effect mechanism.…”

Section: Introductionmentioning

confidence: 99%

Correlation of Exchange Bias and Angle on Applied Perturbation Field and Anti-Ferromagnetic Spins

Fu¹,

Cao²,

Gao³

et al. 2011

JMP

View full text Add to dashboard Cite

High-resolution anisotropic magneto-resistance measurement (AMR) was used to detailed study the training effect in exchange biased CoO/Co bi-layer. The sample was cooled to 10 K from room temperature in the magnetic cooling field of 4000 Oe. Then we used 1500 Oe declined perturbation field to pin the magnetization orientation of the FM layer. The perturbation field forms certain angle Θ with the cooling field direction in-plane to re-induce the untrained state. The dependence of the untrained state on the angle between the direction of perturbation field and cooling field has been investigated. The AMR results reveal that the re-induced degree of untrained state is strongly correlated to the angle Θ. The exchange bias field H E for different Θ has been determined from the AMR results, which is in apparent agreement with the Meiklejohn-Bean model. The recover degree of untrained state is the largest when the angle is 75˚, which is different from the traditional view point that untrained state should be the maximum when it is perpendicular. The training effect is related to the FM spin orientation, which can induce the change of the interfacial AFM spin reorientation with different angles.

show abstract

“…11 In practice, the situation may be more complex due to the presence of uncompensated spins at the AFM surface as manifested in the strong exchange coupling between AFM and FM, 2 and formation of domain walls in the AFM layer interacting with a FM. [22][23][24] Although it is not straightforward to probe its existence, domain walls may also form in the AFM layer of AFM/S bilayers due to magnetostatic interactions. In a recent work, we have found that magnetostatic interactions between Nb and IrMn/NiFe in a Nb/IrMn/NiFe trilayer induces instability in the exchange bias field at the IrMn/NiFe interfaces.…”

mentioning

confidence: 99%

“…24,27 The latter could be developed in the thin IrMn layer through interaction with Nb below T c . The random distribution of these net surface or volumetric spins 22,23 naturally leads to a non-uniform stray field across the sample plane. The proximity effect is less sensitive to the random distribution of magnetic domains as it is dominantly a surface effect.…”

mentioning

confidence: 99%

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

Yang

Guo

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

Effect of antiferromagnet on superconductivity has been investigated in IrMn/Nb bilayers. Significant suppression of both transition temperature (Tc) and lower critical field (Hc1) of Nb is found in IrMn/Nb bilayers as compared to a single layer Nb of same thickness; the suppression effect is even stronger than that of a ferromagnet in NiFe/Nb bilayers. The addition of an insulating MgO layer at the IrMn-Nb interface nearly restores Tc to that of the single layer Nb, but Hc1 still remains suppressed. These results suggest that, in addition to proximity effect and magnetic impurity scattering, magnetostatic interaction also plays a role in suppressing superconductivity of Nb in IrMn/Nb bilayers. In addition to reduced Tc and Hc1, the IrMn layer also induces broadening in the transition temperature of Nb, which can be accounted for by a finite distribution of stray field from IrMn.

show abstract

Hybrid domain walls and antiferromagnetic domains in exchange-coupled ferromagnet/antiferromagnet bilayers

Cited by 68 publications

References 17 publications

Characteristic temperatures of exchange biased systems

Characteristic temperatures of exchange biased systems

Correlation of Exchange Bias and Angle on Applied Perturbation Field and Anti-Ferromagnetic Spins

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

Contact Info

Product

Resources

About