Positive exchange bias model: Fe/FeF2 and Fe/MnF2 bilayers

Kiwi, Miguel; Mejı́a-López, J.; Portugal, R. D.; Ramírez, Raúl Madrid

doi:10.1016/s0038-1098(00)00333-1

Cited by 65 publications

(46 citation statements)

References 27 publications

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“…Few models were proposed to explain the positive EB in Fe/ FeF 2 and Fe/ MnF 2 bilayers. [18][19][20][21] The evolution of H E and H C with H CF was thought to originate from the competition between the Zeeman energy of the AF spins in an external magnetic field and antiferromagnetic coupling. In Gd-Fe/ Tb-Fe bilayers with antiferromagnetic coupling, however, the positive H E was explained in terms of the hybrid domain wall near interface.…”

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confidence: 99%

Positive exchange biasing inGdFe∕NiCoObilayers with antiferromagnetic coupling

Yang

Sun

et al. 2005

Phys. Rev. B

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Positive exchange biasing ͑EB͒ has first been observed in a variety of antiferromagnet ͑AF͒/ferromagnet ͑FM͒ bilayers with AF materials fluorides, in which the FM and AF layers were argued to have antiferromagnetic coupling at the interface.1 It has been detected recently in ferrimagnet/ ferrimagnet, FM/ferrimagnet bilayers with antiferromagnetic coupling and other systems. [2][3][4][5][6][7] These bilayers have two additional distinguished features. First, the exchange field H E has a crossover from negative values to positive values at a critical value of the cooling field H CF 0 . Second, the coercivity H C has a maximum at H CF 0 , in addition to the normal enhancement due to the EB. 8 Apparently, the EB strongly depends on the magnitude of the cooling field H CF . It is quite different from conventional FM/AF bilayers with ferromagnetic coupling, in which H E and H C are almost independent of H CF if it is larger than the saturation field of the FM layer. 9,10 In the strict sense, the positive EB has been found only in a few FM/AF systems.2-7 Therefore, extensive studies on the mechanism of the positive EB have been hindered and more experiments are required.In this paper, we will study the EB phenomena in FM/AF bilayers by using GdFe͑=Gd 45 Fe 55 ͒ / NiCoO͑=Ni 46 Co 54 O͒ bilayers, where NiCoO and GdFe are typical AF material and ferrimagnetic alloys, respectively.2,11 The atomic magnetic moment of Gd comes from spin and orbital angular momentums and both of them are parallel to the atomic magnetic moment. The atomic magnetic moment of Fe is contributed only from the spin angular momentum because the orbital angular momentum is almost quenched. Due to antiferromagnetic coupling between the spins of Gd and Fe, the atomic magnetic moment of Gd is aligned antiparallel to that of Fe and the macroscopic magnetization of Gd 45 Fe 55 alloys is parallel to that of Gd atoms since the latter is dominant. More remarkably, the magnetizations of NiCoO and GdFe layers can have antiferromagnetic coupling at the interface when the contribution of Gd atoms is larger than that of Fe atoms. This is because the atomic magnetic moment of Gd should also be coupled to Co and Ni atoms in AF bilayers antiferromagnetically at the interface. The compositions of the NiCoO and GdFe layers are selected so that the Néel temperature of the AF layer is lower than the Curie temperature of the GdFe layer and FM and AF layers are coupled antiferromagnetically, where the Néel temperature of the NiCoO layer is 400 K and the Curie temperature of the GdFe layer is 430 K. [11][12][13] A large specimen of GdFe/ NiCoO ͑20 nm͒ bilayer was deposited on Si͑100͒ at ambient temperature by magnetron sputtering system. The base pressure was 2 ϫ 10 −5 Pa and the Ar pressure 0.33 Pa during deposition. GdFe and NiCoO layers were made from GdFe and NiCoO composite targets by dc and rf sputtering, respectively. In experiments, small Gd pieces were put on Fe target and small pieces of CoO on NiO target to form GdFe and NiCoO composite targets. The growth rates ...

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confidence: 99%

Positive exchange biasing inGdFe∕NiCoObilayers with antiferromagnetic coupling

Yang

Sun

et al. 2005

Phys. Rev. B

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“…Moreover, Koon also showed that the magnetic moments in the AF interface layer exhibit canting; in fact, the minimum energy is achieved with the AF spins adopting a relatively small canting angle (0 < 10') relative to the AF bulk easy axis, with a component opposite to the cooling field Hld direction. However this canting, which is the manifestation of the MPE, has a significant magnitude only in the AF layer closest to the interface [21][22][23].…”

Section: Metal-insulator Fm/af Interfacesmentioning

confidence: 98%

Origin of the Magnetic Proximity Effect

Kiwi

2002

MRS Proc.

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The magnetic proximity effect (MPE) has attracted the attention of theorists and experimentalists for at least three decades. Lately, the relevance of the effect for the development of nanodevices has revived interest on the subject. Here we review how the field has evolved, centering our attention on metal-metal and metal-insulator systems. We describe, and critically compare, the different theoretical approaches that have been put forward, as well as their limitations. An evaluation of the relationship between existing theories and available experimental results is also attempted.BEST AVAILABLE COPY

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“…It is notable that values are different for the Ferromagnetic (FM), Antiferromagnetic (AF) layers and the interface. At the interface, the model proposed by Kiwi et al (1999;2000) was used. This model alternates two different interactions at the interface.…”

Section: Model Descriptionmentioning

confidence: 99%

Graphic User Interface for Monte Carlo Simulation of Ferromagnetic/Antiferromagnetic Manganite Bilayers

Barco-Ríos

Rojas-Calderón

2011

TecnoL.

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The manganites have been widely studied because of their important properties as colossal magnetoresistance and exchange bias that are important phenomena used in many technological applications. For this reason, in this work, a study of the exchange bias effect present in La2/3Ca1/3MnO3/La1/3Ca2/3MnO3. This study was carried out by using the Monte Carlo method and the Metropolis Algorithm. In order to make easy this study, a graphic user interface was built alloying a friendly interaction. The interface permits to control the thickness of Ferromagnetic and Antiferromagnetic layer, temperatures the magnetic field, the number of Monte Carlo steps and the exchange parameters. Results obtained reflected the influence of all of these parameters on the exchange bias and coercive fields. KeywordsBilayers, exchange bias, graphic interface, manganites. ResumenLas manganitas han sido ampliamente estudiadas debido a sus propiedades importantes tales como magnetorresistencia colosal y polarización de intercambio, que son fenómenos importantes empleados en diversas aplicaciones tecnológicas. Por esta razón, en este trabajo se presenta el estudio del efecto de la polarización de intercambio (exchange bias) para el caso de bicapas de La2/3Ca1/3MnO3/La1/3Ca2/3MnO3. Este estudio se llevó a cabo empleando el método de Monte Carlo junto con el algoritmo de Metropolis. Con el fin de que este estudio sea más fácil, se construyó una interface gráfica para hacer más amigable la interacción con el usuario. La interface permite el control de parámetros como el espesor de la película, la temperatura, el campo magnético el número de pasos de Monte Carlo y los parámetros de intercambio. Los resultados obtenidos reflejaron la influencia de todos estos paráme-tros sobre el Exchange bias y el campo coercitivo. Palabras claveBicapas, polarización de Intercambio, interfaz gráfica, manganitas.Revista Tecno Lógicas No. 26, Junio de 2011 [135]

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Positive exchange bias model: Fe/FeF2 and Fe/MnF2 bilayers

Cited by 65 publications

References 27 publications

Positive exchange biasing inGdFe∕NiCoObilayers with antiferromagnetic coupling

Positive exchange biasing inGdFe∕NiCoObilayers with antiferromagnetic coupling

Origin of the Magnetic Proximity Effect

Graphic User Interface for Monte Carlo Simulation of Ferromagnetic/Antiferromagnetic Manganite Bilayers

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