Magnetoelastic dependence of switching field in TbFe–FeCo giant magnetostrictive spring-magnet multilayers

Chopra, Harsh Deep; Yang, David; Wilson, P.R.

doi:10.1063/1.372520

Cited by 14 publications

(7 citation statements)

References 9 publications

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“…Further results on structure and magnetic behavior are given elsewhere. [5][6][7][8][9] The results on the FePd system are preliminary in nature, and detailed studies will be reported in a later manuscript. The FePd and FePd/ Fe multilayers were deposited by dc magnetron sputtering in Ar pressure ranging from 3 mTorr to 10 mTorr and power from 30 to 120 W. The composition of the FePd films was varied either by sputtering Fe-30 at.…”

Section: Methodsmentioning

confidence: 91%

“…Kneller's exchange-spring mechanism 4 is a striking illustration of how the switching fields can be reduced and strain susceptibility enhanced. [5][6][7][8][9] While Kneller initially described the exchangespring mechanism to develop magnets, exchange coupling can also be used to decrease the switching field, which is proportional to the ratio of anisotropy K to saturation magnetization M s . 10 This is achieved by sandwiching high switching field actuator thin films between high magnetization, soft magnets such as Fe or Fe 50 Co 50 .…”

Section: Introductionmentioning

confidence: 99%

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Magnetoelastic and magnetostatic interactions in exchange-spring multilayers

et al. 2005

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The macroscopic or average aggregate behavior of Kneller's exchange-spring mechanism is well established and widely examined; less is known about its microscopic details. In the present study, the microscopic nature of exchange spring was investigated using TbFe/ FeCo multilayers and correlated with their aggregate behavior ͑magnetostriction, torque, and magnetization curves͒. Results show that, as predicted, the exchange-coupled geometry reduces the switching field by increasing the average magnetization and decreasing the average anisotropy of the multilayers. However, it is the magnetostatic interactions between domain walls in adjacent layers that lead to a reduction in coercivity. Stray fields emanating from domain walls in a given layer magnetostatically lock in with the stray fields from walls in adjacent layers, giving rise to low energy, low coercivity "twin" walls. Since in a multilayer a wall can magnetostatically lock in with walls in layers both above and below it for optimum flux closure, a sharp drop in coercivity is observed when the number of bilayers exceeds two. Preliminary results on Fe-Pd based shape memory alloy ͑SMA͒ thin films and multilayers are also given to further emphasize the efficacy of the exchange-spring mechanism as well as to highlight a key micromagnetic difference between magnetostrictive and magnetic SMA films. In particular, the number of martensite variants is greatly reduced because variants with easy axis normal to the plane of the film are prohibited due to magnetostatic considerations.

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Section: Methodsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Magnetoelastic and magnetostatic interactions in exchange-spring multilayers

et al. 2005

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“…6(a). The behavior can be explained using a theoretical expression postulated by Chopra on the basis of a magnetic collinear structure [15]. Applying this to the present case, the coercivity can be described as follows: Fig.…”

Section: Magnetization Loops Of Different Singe Filmsmentioning

confidence: 98%

Excellent magnetic softness in TbFe/FeCoV multilayers

Feng

Chen

2011

Rare Metals

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Tb 40 Fe 60 (x nm)/Fe 49 Co 49 V 2 (y nm)] N multilayers were prepared by multitarget magnetron sputtering using a rotary turn-table technique in a stop-and-go mode. The multilayers were investigated using X-ray diffraction, field emission scan electron microscopy and vibrating sample magnetometry. The result shows that the coercive field drops abruptly with increasing number of bilayers, and it remains generally stable when the number of bilayers is 10 or higher. An excellent magnetic softness with a coercivity of 1.0 mT is obtained for x = 5 and y = 5 after annealing at 250°C. A crystalline state is observed in FeCoV layers before and after annealing by X-ray diffraction.

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“…[1][2][3] In an exchangespring magnetic system, the soft magnetic phase exhibits magnetization reversal prior to the magnetization reversal in the hard magnetic phase due to a strong magnetic exchange coupling. 4 A large number of exchange-spring systems studied are multilayers of RE-Fe 2 /(R*Fe 2 or TM), where RE ¼ rare earth elements, R* ¼ Y, and TM ¼ Fe and Co. [5][6][7][8][9][10][11][12][13][14] In these layered systems, the film's thickness ratio (t S /t H ) and/or the materials anisotropy is used to modify the coercivity/remanence values and cannot be modified once manufactured. However, many RE-Fe 2 materials exhibit strong magnetoelastic coupling 15 suggesting that the magnetic anisotropy can be changed in-situ by applying an external mechanical load (or applying an electric field induced strain), thereby tuning the exchange-spring phenomenon and/or the coercivity/remanence values.…”

Section: Introductionmentioning

confidence: 99%

Strain induced exchange-spring magnetic behavior in amorphous (TbDy)Fe2 thin films

Mohanchandra

Prikhodko²,

Wang

et al. 2017

Journal of Applied Physics

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In this paper, we report a strain induced exchange-spring magnetic behavior in sputter deposited (TbDy)Fe 2 amorphous thin films with phase-separated layers of (TbDy)-rich and Fe-rich at room temperature. The magnetic hysteresis loops at different strain levels were obtained with a magneto-optic Kerr effect setup incorporating a mechanical four-point bending fixture. The unstrained film exhibits a typical ferrimagnetic hysteresis loop while the strained structure exhibits step-like hysteresis loops representative of an exchange-spring magnetic system. The mechanically strained film changes the coercivity/remanence values from positive to negative. The observed magnetic changes under strain are attributed to magnetic anisotropy modifications in the highly magnetoelastic TbDy-rich layer.

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Magnetoelastic dependence of switching field in TbFe–FeCo giant magnetostrictive spring-magnet multilayers

Cited by 14 publications

References 9 publications

Magnetoelastic and magnetostatic interactions in exchange-spring multilayers

Magnetoelastic and magnetostatic interactions in exchange-spring multilayers

Excellent magnetic softness in TbFe/FeCoV multilayers

Strain induced exchange-spring magnetic behavior in amorphous (TbDy)Fe2 thin films

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