Magnetocaloric effect in nanoscale thin films and heterostructures

Miller, Casey W.; Belyea, Dustin D.; Kirby, Brian J.

doi:10.1116/1.4882858

Cited by 59 publications

(44 citation statements)

References 118 publications

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“…This was done from a Ni 81 Fe 19 target at a deposition rate of 0.044 nm/s, and from an elemental Gd target at a deposition rate of 0.057 nm/s. We note that the growth of high quality Gd in this sputter tool has been previously accomplished 29 , with protocols published elsewhere 30 .…”

Section: Methodsmentioning

confidence: 99%

Enhanced spin pumping near a magnetic ordering transition

et al. 2017

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We study the temperature-dependent static and dynamic magnetic properties of polycrystalline permalloy (Ni 80 Fe 20 , Py)/Gd bilayers using DC magnetometry and broadband ferromagnetic resonance. Magnetometry measurements reveal that the 3-nm-thick Gd layers undergo a magnetic ordering transition below 100 K, consistent with finite size suppression of their Curie temperature. Upon cooling below this Gd ordering temperature, ferromagnetic resonance spectroscopy reveals a sharp increase in both the gyromagnetic ratio (γ) and effective Gilbert damping parameter (α) of the neighboring Py layers. The increase of γ is attributed to the onset of strong antiferromagnetic coupling between the Gd and Py layers as the Gd orders magnetically. We argue that the increase of α, on the other hand, can be explained by spin pumping into the rare earth layer when taking into account the increase of γ, the decrease of the Gd spin diffusion length as it orders, and, most significantly, the corresponding increase of the Py/Gd interfacial spin mixing conductance in the vicinity of the magnetic ordering transition. We propose that these observations constitute a qualitative confirmation of a recent theoretical prediction of spin sinking enhancement in this situation.2

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Section: Methodsmentioning

confidence: 99%

Enhanced spin pumping near a magnetic ordering transition

et al. 2017

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“…Since that time the quantity of papers on this subject has increased substantially in leading world journals (see reviews on MCE in perovskites [6] and, in particular, manganites [7] and other systems [8]). Nowadays, in addition, experimental investigations of MCE in nanomaterials, heterostructures, and thin films have been performed [9]. Approaches to studying MCE were described most comprehensively in review [10].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the magnetocaloric effect in correlated metallic systems with Van Hove singularities in the electron spectrum

Igoshev

Kokorina

Некрасов

2017

Phys. Metals Metallogr.

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Abstract⎯In this work, the magnetic contribution to the isothermal entropy change upon switching on a magnetic field has been investigated in correlated metallic ferromagnets within the Hubbard nondegenerate model. The analytical expression for obtained in the mean-field approximation depends substantially on the electronic structure (density of electron states), which presents new ways to increase the absolute value of relative to the known result obtained within the Heisenberg model. The temperature dependence of has been calculated at different values of the Coulomb interaction U and the number of electrons n for the Bethe infinite-dimensional lattice and square lattice with allowance for transfer integrals in the first (t) and the second (t') coordination shells. It has been found that the presence of Van Hove singularities in the electronic spectrum near the Fermi level makes it possible to considerably increase at a fixed magnetic field. The possibility of first-order magnetic phase transitions depending on the model parameters has been analyzed.

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“…15 Since the discovery of the GMCE, 1 an intense and devoted effort has been focused in the bulk magnetocaloric materials and in macroscale magnetic refrigeration systems. On the other end of the scale spectrum, the nanoscalling processing has just recently been attracting more attention, resulting in an exponential increase of papers published as shown by Miller and co-workers, 19 but still lagging behind other caloric materials in the nanoscalling race, as Moya and co-workers pointed recently. 20 From the scientific point of view, the importance to understand the behavior of the magnetostructural coupling with the dimension reduction is crucial.…”

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confidence: 98%

Gd5(Si,Ge)4 thin film displaying large magnetocaloric and strain effects due to magnetostructural transition

Hadimani

Silva

Pereira

et al. 2015

Applied Physics Letters

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Magnetic refrigeration based on the magnetocaloric effect is one of the best alternatives to compete with vapor-compression technology. Despite being already in its technology transfer stage, there is still room for optimization, namely, on the magnetic responses of the magnetocaloric material. In parallel, the demand for different magnetostrictive materials has been greatly enhanced due to the wide and innovative range of technologies that emerged in the last years (from structural evaluation to straintronics fields). In particular, the Gd5(SixGe1−x)4 compounds are a family of well-known alloys that present both giant magnetocaloric and colossal magnetostriction effects. Despite their remarkable properties, very few reports have been dedicated to the nanostructuring of these materials: here, we report a ∼800 nm Gd5Si2.7Ge1.3 thin film. The magnetic and structural investigation revealed that the film undergoes a first order magnetostructural transition and as a consequence exhibits large magnetocaloric effect (−ΔSmMAX ∼ 8.83 J kg−1 K−1, ΔH = 5T) and giant thermal expansion (12000 p.p.m). The thin film presents a broader magnetic response in comparison with the bulk compound, which results in a beneficial magnetic hysteresis reduction. The ΔSmMAX exhibited by the Gd5(Si,Ge)4 thin film makes it a promising candidate for micro/nano magnetic refrigeration area.

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Magnetocaloric effect in nanoscale thin films and heterostructures

Cited by 59 publications

References 118 publications

Enhanced spin pumping near a magnetic ordering transition

Enhanced spin pumping near a magnetic ordering transition

Investigation of the magnetocaloric effect in correlated metallic systems with Van Hove singularities in the electron spectrum

Gd5(Si,Ge)4 thin film displaying large magnetocaloric and strain effects due to magnetostructural transition

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