Enhancement of perpendicular exchange bias in [Pd/Co]/FeMn thin films by tailoring the magnetoelastically induced perpendicular anisotropy

Lin, Lin; Thiyagarajah, Naganivetha; Joo, Ho Wan; Heo, Jang; Lee, Ky Am; Bae, Seongtae

doi:10.1063/1.3526735

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…6 In most PEB systems, multilayers of repeating Co/Pt, Co/Ni, and Co/Pd bilayers with perpendicular magnetic anisotropy (PMA) are used as FM layers. [7][8][9][10] However, the thickness of the interleaving layers in these multilayers must be precisely controlled down to the subnanometer level to maintain PMA, posing difficulties in the manufacture of devices. 11 In this context, singlelayered alloy film as the FM layer of PEB systems have recently been given considerable attention.…”

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confidence: 99%

Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study

Tsai

Hsu

Lin

2015

Journal of Applied Physics

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In this study, FeMn was introduced as an antiferromagnetic (AFM) layer to couple with a single-layered Co49Pt51 alloy thin film, and it was compared with a Co49Pt51/IrMn bilayer system in exchange bias (EB) effect, to explore the mechanism of spontaneous perpendicular exchange bias (PEB), which has been recently observed in CoPt/IrMn bilayers. Bilayers of CoPt/IrMn and CoPt/FeMn were prepared under the same conditions by sputtering at room temperature without any inducing field. Although PEB was observed in as-grown CoPt/FeMn bilayers, the loop shape and PEB behavior were found to exhibit different characteristics from those of CoPt/IrMn bilayers. The CoPt (5 nm)/FeMn (10 nm) bilayer has a sheared loop that is similar to a double-shifted loop and a much lower squareness ratio (SQR = 0.52) and exchange bias field (He = 180 Oe) than the CoPt (5 nm)/IrMn (10 nm) system, which has a rectangular loop shape and a high SQR of 0.97 and large He of 290 Oe. The two systems present entirely different dependences of PEB on the thickness of the AFM layer. CoPt/IrMn exhibits behavior that is typical of most EB systems, but for CoPt/FeMn, this dependence is more complicated with an unusual peak at an AFM layer thickness of 10 nm. Based on the dissimilar loop shapes and dependences of PEB on AFM thickness, the mechanisms of the spontaneously established PEB in these two systems are considered to differ. Investigations of cross-sectional transmission electron microscopy revealed no apparent difference between the interfacial microstructures of the two systems. X-ray diffraction studies demonstrated the ⟨111⟩ texture of both systems. Therefore, different interfacial spin configurations may be responsible for the dissimilar PEB behaviors in these two FM/AFM bilayer systems.

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confidence: 99%

Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study

Tsai

Hsu

Lin

2015

Journal of Applied Physics

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“…Perpendicular exchange bias (PEB) has been observed in Co(CoFe)/Pt (Pd) multilayers coupled with an AFM material such as CoO, NiO, FeMn, or IrMn. [8][9][10][11][12][13][14] However, most of the reported values for the PEB field are at best comparable to the coercive field and may be too weak for practical applications. Many researchers have tried to improve the PEB using different methods.…”

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confidence: 99%

Perpendicular exchange bias effect in sputter-deposited CoFe/IrMn bilayers

Chen

Thiyagarajah

et al. 2014

Applied Physics Letters

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CoFe/IrMn bilayers with perpendicular magnetization for various IrMn layer thicknesses exhibit unusual two-step hysteresis loops with both positive and negative loop shifts. Observed at room temperature in the as-grown state, they provide direct evidence of large antiferromagnetic domain formation at the IrMn interface. The exchange bias field reaches 100 mT with an IrMn layer thickness of 4 nm after field annealing at 200 C-300 C in 800 mT, which is at least three times as large as the coercivity, and may be useful for reference layers of spin-valves or magnetic tunnel junctions with perpendicular magnetic anisotropy. V

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“…We focused on the correlation between m and f , due to their direct ferromagnetic exchange‐coupling at the interface. [ 45–47 ] These results indicate that the β‐dependent ADMR generally fit the cosine square correlation except at angles between 150 ° to 270 ° . This deviation can be explained by the evolution of the relationship between f and af accompanying CoFeB reversal.…”

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confidence: 79%

A Spin‐Orbit Torque Ratchet at Ferromagnet/Antiferromagnet Interface via Exchange Spring

Yu-Han

Yang

Cheng

et al. 2022

Adv Funct Materials

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The antiferromagnet (AFM) and ferromagnet (FM) interface is a unique branch of magnetics of broad scientific interest. AFMs play an important role in spin-orbit torque devices based on their ability to generate spin-polarized current and exchange bias when combined with FMs. In this study, an interesting spin-orbit torque (SOT) ratchet involving the exchange spring effect in an IrMn/CoFeB bilayer device with perpendicular anisotropy and exchange bias is developed. The combined use of electrical and spectroscopic analysis reveals that the exchange spring in IrMn/CoFeB bilayer yields unidirectional anisotropy, resulting in a collinear/orthogonal AFM/FM spin configuration at the interface upon switching CoFeB magnetization upward/downward. The ratcheting characteristics resulting from unidirectional anisotropy manifest in SOT switching. In this process, magnetization against the exchange spring features digital-like switching with a sharp transition, whereas the reverse function is characteristic of analog switching with a gradual transition tail. The dual digital-analog characteristics of the IrMn/CoFeB bilayer may be of benefit in neuromorphic and memory applications.

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Enhancement of perpendicular exchange bias in [Pd/Co]/FeMn thin films by tailoring the magnetoelastically induced perpendicular anisotropy

Cited by 13 publications

References 10 publications

Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study

Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study

Perpendicular exchange bias effect in sputter-deposited CoFe/IrMn bilayers

A Spin‐Orbit Torque Ratchet at Ferromagnet/Antiferromagnet Interface via Exchange Spring

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