Pinning-assisted out-of-plane anisotropy in reverse stack FeCo/FePt intermetallic bilayers for controlled switching in spintronics

Vashisht, Garima; Shashank, Utkarsh; Gupta, Surbhi; Medwal, Rohit; Dong, Chung‐Li; Chen, C.L.; Fukuma, Yasuhiro; Annapoorni, S.

doi:10.1016/j.jallcom.2021.160249

Cited by 9 publications

(5 citation statements)

References 60 publications

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“…The increased coercivity in OOP hysteresis is attributed to interfacial diffusion which give rise to pinning centres. After heat treatment, the interface is more susceptible to diffusion, resulting in higher OOP coercivity in annealed sample [33,53]. These bulk magnetic properties further support the deposition of permalloy without any impurities or oxides which are also confirmed by the synchrotron XRD data.…”

Section: Magnetic Measurementssupporting

confidence: 70%

Magnetization dynamics and domain reversal in electrodeposited permalloy thin films: impact of thickness and annealing treatment

Dev,

Reddy,

Medwal

et al. 2024

Phys. Scr.

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The domain reversal and magnetization dynamics of electrodeposited permalloy (Fe20Ni80) thin films on conducting ITO/glass substrate was investigated using Magneto-optic Kerr effect microscopy and ferromagnetic resonance. Permalloy thin films were electrodeposited with thickness ranging from 66 nm to 330 nm. Synchrotron XRD confirmed the deposited permalloy in FCC phase without any impurity. The squared hysteresis with very low coercivity (Hc ~ 5 Oe) established soft magnetic nature of the films. Further, angular MOKE hysteresis measurements with simultaneous domain imaging revealed four-fold surface anisotropy in as-deposited film ensuing magnetization reversal via branched and ripple domains. The annealing treatment in Ar+H2 atmosphere removed surface anisotropy and renovated the magnetization reversal through 180˚ branched domains with rapid magnetization switching. Ferromagnetic resonance spectroscopy discloses reduction in the gyromagnetic ratio (γ) as well as in Gilbert damping parameter (α) as the film thickness increases. The lowest Gilbert damping for 330 nm film measured at 0.022, which further reduced to 0.018 after annealing. The combination of rapid magnetization switching and low Gilbert damping in the electrodeposited permalloy thin films render them promising for implementation in high-frequency microwave devices devices and magnetic sensors.

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Section: Magnetic Measurementssupporting

confidence: 70%

Magnetization dynamics and domain reversal in electrodeposited permalloy thin films: impact of thickness and annealing treatment

Dev,

Reddy,

Medwal

et al. 2024

Phys. Scr.

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“…K eff was estimated to be 1.0 × 10 5 J m −3 and 1.6 × 10 5 J m −3 for S1 and S2 respectively. It is well-demonstrated that the change in lattice parameters accompanied by electronic structure modulations of FePt at the interface of FePt/FeCo bilayers changes the anisotropy of the system [38]. Therefore, this increase in effective anisotropy constant on decreasing the diffusion between FeCo and FePt could be strongly correlated with the structural variations in FePt and charge transfer process with diffusion as explained in the XRD and XAS section.…”

Section: Resultsmentioning

confidence: 86%

Domain state modulation by interfacial diffusion in FePt/FeCo thin films: experimental approach with micromagnetic modelling

Vashisht

Hussain

Sulania

et al. 2021

J. Phys.: Condens. Matter

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We report the complex implications of inter-diffusion between polycrystalline FePt/FeCo layers as an impact of the FeCo underlayer on the structural and magnetic properties of the system. The crystalline growth of FePt strongly reduces in an entirely diffused system compared to the one with lesser diffusion, while the crystalline structure of FeCo is apparently less affected. Charge redistribution occurs between Fe, Co and Pt ensuring increased Co-Pt and Fe-Pt interactions with higher diffusion. Thereafter, we combine hysteresis and magnetic force microscopy measurements to show that the interfacial deformations result in the distinct out-plane magnetic behaviour of the system. FeCo@FePt nano-composite like structure, originating due to interfacial diffusion, shows interactions between two magnetic phases with in-plane low anisotropy exhibiting wasp-shaped out-plane hysteresis loop. Whereas the layered structure of FePt/FeCo films shows random anisotropy with a significant out-plane contribution even in the polycrystalline films. Micromagnetic modelling demonstrates coercivity deterioration and reduction of switching field due to the formation of a slightly diffused interface. Contrarily, the experimental observations for complete diffusion between the two layers are explained by simulating the inhomogeneous distribution of anisotropies along the film plane. These studies provide deep perceptions of the magnetic properties of FePt/FeCo system governed by diffusion kinetics which are valuable to achieve desired magnetic characteristics using this system.

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“…However, out-of-plane hysteresis of S1 reveals a slight enhancement in coercivity. A possible reason for this could be the pinning of magnetization due to interfacial deformations in the multilayer structure [41]. The hysteresis curve for S2 and S3 measured in out-of-plane and in-plane geometry suggests that saturation magnetization and coercivity are maximum for S2, indicating the highest degree of ordering in S2 after annealing for 120 s at 400 °C.…”

Section: Resultsmentioning

confidence: 99%

Atomic level mechanism of disorder-order transformation kinetics at nanoscale in FePt based systems

Kumar,

Tiwari,

Gupta

et al. 2024

Phys. Scr.

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L10 ordered FePt is one of the most promising materials for spintronic and recording media applications. In the present work, the mechanism of L10 phase transformation in FePt based films with varying initial structures is examined at the nanoscale to understand the ordering process using synchrotron based GIXRD, MOKE, VSM, and techniques with sub nanometer depth selectivity like XRR and SIMS. Precisely controlled compositions of the films are deposited using magnetron sputtering. Rapid thermal annealing is used for post-deposition processing. It is evaluated experimentally that for a shorter annealing time of 70 s at 400oC, besides volume diffusion, short circuit diffusion paths along the intercrystallite region owing to the presence of nanostructured grains play a dominant role in alloying behavior. A study of the L10 ordering process reveals the crucial role of film structure in controlling the transformation kinetics, texturing of nanograins, and magnetic coercivity. Diffusion studies disclose that type B diffusion kinetics is activated for the annealing time during which L10 transformation occurs in the films.

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Pinning-assisted out-of-plane anisotropy in reverse stack FeCo/FePt intermetallic bilayers for controlled switching in spintronics

Cited by 9 publications

References 60 publications

Magnetization dynamics and domain reversal in electrodeposited permalloy thin films: impact of thickness and annealing treatment

Magnetization dynamics and domain reversal in electrodeposited permalloy thin films: impact of thickness and annealing treatment

Domain state modulation by interfacial diffusion in FePt/FeCo thin films: experimental approach with micromagnetic modelling

Atomic level mechanism of disorder-order transformation kinetics at nanoscale in FePt based systems

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