Magnetization switching diagram of a perpendicular synthetic ferrimagnet CoFeB/Ta/CoFeB bilayer

Коплак, О. В.; Таланцев, А. Д.; Lü, Yuan; Hamadeh, A.; Pirro, Philipp; Hauet, Thomas; Моргунов, Р. Б.; Mangin, Stéphane

doi:10.1016/j.jmmm.2017.02.047

Cited by 34 publications

(31 citation statements)

References 46 publications

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“…Therefore, the aforementioned mechanisms could explain the spin reversal and exchange bias sign change of AFM with or with less M para . Moreover, it could be popularized to all other AFM/FM, FM/FM, ferrimagnet/FM, and ferrimagnet/ferrimagnet exchange coupling systems, and their future device applications.…”

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confidence: 99%

Spin Reversal Mechanism of a Perpendicular Exchange Bias System with an Antiferromagnet Incorporating a Parasitic Ferromagnetism

Shiokawa

Pati

et al. 2019

Physica Rapid Research Ltrs

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Aluminum doping produced the parasitic magnetization (M para ) with high coercivity in 20 nm thin antiferromagnetic Cr 2 O 3 films. By using the large coercive force of M para , whose direction is the same as the antiferromagnetic Cr 2 O 3 surface spin, antiferromagnetic spin reversal can be detected through the vertical shift of the hysteresis loop of an antiferromagnetic-Cr 2 O 3 / ferromagnet perpendicular exchange bias (PEB) coupling system. By analyzing both antiferromagnetic and ferromagnetic spin reversals in response to external magnetic field and temperature, each spin reversal mechanism in a PEB system is clarified. It is found that the competition among Zeeman energy due to M para , exchange coupling energy, and antiferromagnetic anisotropy energy decides the antiferromagnetic spin direction and, accordingly, PEB sign under different cooling fields, different temperatures, and different swept magnetic fields for PEB systems. This work might contribute to a deep understanding of spin reversal mechanism in a perpendicular exchange bias system.Antiferromagnetic spin is difficult to detect and control, which enables its hardness for an external magnetic field. Moreover, an antiferromagnet (AFM) also has ultrafast spin dynamics to terahertz, which makes its switching much faster than that of a ferromagnet (FM). Therefore, AFMs are widely studied in many fields. [1][2][3][4] In particular, nonvolatile magnetic random-access memory (MRAM) is expected to replace volatile DRAM and SRAM in computing systems. [5] The exchange bias at the interface between AFM and FM is an important physical phenomenon, of which the hysteresis loop shift left (negative) or right (positive) of field axis could be obtained because of exchange bias coupling. [6] The in-plane exchange bias has already been used in hard-disk drive heads. Perpendicular exchange bias (PEB) devices attract more attention because of their higher integrated density compared with that of in-plane exchange bias. PEB devices have been used for spin pinning in magnetoresistance tunneling junction devices. Also owing to the difficult detection of the AFM spin, the spin reversal during PEB has been rarely reported. X-ray magnetic circular dichroism was widely used to detect the surface spin direction of AFM at certain temperature and external magnetic field. [7] However, as discussed later, the antiferromagnetic spin direction at certain temperature and external magnetic field differs for various cooling fields and scanning fields. In addition, there are few reports on the detection of antiferromagnetic spin direction during PEB under continuous changes of temperature and magnetic field.Cr 2 O 3 , an AFM with a Neel temperature (T N ) of 307 K, has two kinds of spin directions þÀþÀ and ÀþÀþ along the c-axis direction of its corundum structure, which can store information of 0 and 1. It has a magnetoelectric effect that can switch its spin directions and work as information writing for a MRAM. Reading can be realized through PEB-coupled ferromagnetic materials (Co...

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confidence: 99%

Spin Reversal Mechanism of a Perpendicular Exchange Bias System with an Antiferromagnet Incorporating a Parasitic Ferromagnetism

Shiokawa

Pati

et al. 2019

Physica Rapid Research Ltrs

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“…The accurate map of the temperature and field dependent states of the studied spin valve and description of the transitions between stable magnetization states were presented in Ref. 12.…”

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confidence: 99%

Remote microwave monitoring of magnetization switching in CoFeB/Ta/CoFeB spin logic device

Моргунов

L’vova

Таланцев

et al. 2017

Applied Physics Letters

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Stable magnetic states of the MgO/CoFeB/Ta/CoFeB/MgO/Ta spin valve as well as transitions between the states were detected by microwave magnetoresistance (MMR) measured in the cavity of an electron spin resonance spectrometer. Advantages of this experimental technique are the possibility to study the orientation dependence of the MMR, the absence of the additional contact/sample interfaces, the wireless control of the spin valves, and the compatibility of the MMR measurements with ferromagnetic resonance experiments. The magnetic field dependence of the first derivation of the microwave absorption allows one to judge about the negative magnetoresistance of the layers and positive interlayer giant magnetoresistance. The obtained experimental results could be used for engineering of the microwave high sensitive sensors available for remote identification of the stable magnetic and logic states of the spin valves needful in medical spintronics to detect biological objects labeled with nanoparticles.

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“…The outer loops with H C2 ∼ 5 Oe coercivity are formed by P + ↔ AP + and AP -↔ P -transitions. The centers of these loops are shifted to ±H B = ±200 Oe due to negative exchange coupling between the two layers as discussed in our previous work [6].…”

Section: A Magnetic Hysteresis and Microstructure Of The Bilayermentioning

confidence: 56%

“…The multilayer stack was grown directly on a GaAs substrate. Quasistatic magnetization versus field hysteresis loops were measured for different temperatures ranging from 5 to 300 K. It allowed a field-temperature (H -T ) magnetization switching diagram to be constructed [6]. Now we would like to focus on the magnetization dynamics during the transition from one magnetic state to the other.…”

Section: Introductionmentioning

confidence: 99%

Magnetic aftereffects in CoFeB/Ta/CoFeB spin valves of large area

et al. 2017

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Magnetic aftereffect measurements on a synthetic antiferromagnet with strong perpendicular anisotropy are presented. Two types of magnetic transitions are observed in the CoFeB/Ta/CoFeB bilayer where the two ferromagnetic CoFeB layers are antiferromagnetically coupled: the transition from a parallel to an antiparallel CoFeB layers magnetization alignment and the transition between two possible antiparallel magnetization states. Magnetic relaxation measurements show a complete reversal in the case of the transition between the two antiferromagnetic configurations. The experimental data can be well fitted in the frame of extended exponential relaxation using the Fatuzzo-Labrune model. Consequently, the domain nucleation and domain-wall propagation can be studied as a function of temperature and applied field.

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Magnetization switching diagram of a perpendicular synthetic ferrimagnet CoFeB/Ta/CoFeB bilayer

Cited by 34 publications

References 46 publications

Spin Reversal Mechanism of a Perpendicular Exchange Bias System with an Antiferromagnet Incorporating a Parasitic Ferromagnetism

Spin Reversal Mechanism of a Perpendicular Exchange Bias System with an Antiferromagnet Incorporating a Parasitic Ferromagnetism

Remote microwave monitoring of magnetization switching in CoFeB/Ta/CoFeB spin logic device

Magnetic aftereffects in CoFeB/Ta/CoFeB spin valves of large area

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