Strain engineering of magnetocaloric effect in W/Gd/W/MgO structures

Коплак, О. В.; Kashin, S.; Моргунов, Р. Б.

doi:10.1016/j.jmmm.2022.170164

Cited by 6 publications

(9 citation statements)

References 31 publications

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“…Пленочные гетероструктуры W/Gd/W/MgO были получены методом магнетронного напыления в условиях высокого вакуума, как это описано в [11,12]. Толщина слоя гадолиния составляла 300 nm.…”

Section: методика и образцыunclassified

“…Кроме того, значительная анизотропия намагниченности в микропроволоках и пленках, возникающая из-за текстурирования материала, может быть использована для совершенствования конструкции холодильной машины. В частности, в [11,12] показано, что изменение кристаллографической ориентации подложки гадолиниевой пленки и соответствующих внутренних напряжений, создаваемых подложкой в пленке, способно приводить к значительному изменению МКЭ. В объемных образцах гадолиния кристаллическая анизотропия намагниченности значительно меньше, чем это наблюдается в пленках и микропроводах.…”

Section: Introductionunclassified

“…Это обеспечивает отсутствие энергозатратной процедуры включения поля или перемещения образца, позволяя просто вращать его в магнитном поле постоянного магнита. Сравнение МКЭ в микропроводах и пленках в [11][12][13] показывает, что при постоянном химическом составе и температурных режимах приготовления микро-и наноструктуры могут демонстрировать значительно отличающийся по величине МКЭ, что вызвано вариациями фазового состава и внутренними микронапряжениями. Разумеется, при оценке МКЭ следует учитывать так же и фактор размагничивания, зависящий от формы образца, как это убедительно показано в [14,15].…”

Section: Introductionunclassified

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Магнитные свойства и магнитокалорический эффект в пленках и микропроводах Gd

Коплак¹,

Кашин²,

Королев³

et al. 2023

Физика Твердого Тела

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An analysis of the temperature and field dependences of the magnetization of Gd films and microwires was carried out, as well as an isothermal measurement of the magnetic part of the entropy at the Curie temperature. The magnetocaloric effect (MCE), measured as an isothermal increase in the magnetic part of the entropy, in microwires shows two peaks on the temperature dependence of the magnetic part of the entropy, in contrast to one peak in films. In films and microwires, the entropy maximum at 286–293 K, which corresponds to the Curie temperature, depends on the magnetic field, shifting in the same way in films and microwires with an increase in the field at the orientation of the MgO (111) substrate, which provides the maximum mechanical stresses in Gd. In microwires, the second maximum does not change the temperature of 320 K as the field increases to 9 T, but its amplitude increases linearly with the field. This maximum can be caused by a spin-reorientation transition.

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Section: методика и образцыunclassified

Section: Introductionunclassified

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Магнитные свойства и магнитокалорический эффект в пленках и микропроводах Gd

Коплак¹,

Кашин²,

Королев³

et al. 2023

Физика Твердого Тела

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show abstract

“…In addition, the considerable anisotropy of magnetization in microwires and films arising due to the texture of the material can be used to improve the refrigerating machine design. In particular, in [11,12] it is shown, that a change in the crystal-lattice orientation of the gadolinium film substrate and in appropriate internal stresses created by the substrate in the film, can result in a significant change in MCE. Bulk gadolinium samples have significantly lower crystal anisotropy of magnetization that the anisotropy observed in films and microwires.…”

Section: Introductionmentioning

confidence: 99%

“…This provides for avoiding the energy-intensive procedure of switching-on the field or moving the sample, allowing simply rotate it in the magnetic field of a permanent magnet. The comparison of MCE in microwires and films presented in [11][12][13] shows that with constant chemical composition and temperature modes of their preparation, micro-and nanostructures can demonstrate MCE with considerably different magnitude, which is caused by variations of the phase composition and internal microstresses. Indeed, the MCE estimate should also take into account the factor of demagnetization, which depends on the sample's shape, as it is convincingly demonstrated in [14,15].…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties and magnetocaloric effect in Gd films and microwires

Коплак

Kashin

Королев

et al. 2023

Physics of the Solid State

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An analysis of the temperature and field dependences of the magnetization of Gd films and microwires was carried out, as well as an isothermal measurement of the magnetic part of the entropy at the Curie temperature. The magnetocaloric effect (MCE), measured as an isothermal increase in the magnetic part of the entropy, in microwires shows two peaks on the temperature dependence of the magnetic part of the entropy, in contrast to one peak in films. In films and microwires, the entropy maximum at 286-293 K, which corresponds to the Curie temperature, depends on the magnetic field, shifting in the same way in films and microwires with an increase in the field at the orientation of the MgO (111) substrate, which provides the maximum mechanical stresses in Gd. In microwires, the second maximum does not change the temperature of 320 K as the field increases to 9 T, but its amplitude increases linearly with the field. This maximum can be caused by a spin-reorientation transition. Keywords: microwires, thin films, magnetic entropy, magnetic anisotropy, spin-reorientation transition, Curie temperature.

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Direct measurements of the conventional and rotational magnetocaloric effects in Gd thick films

Pereira,

Almeida,

Niehoff

et al. 2024

J. Phys. D: Appl. Phys.

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Magnetic refrigeration offers a sustainable and emission-free solution to the prevalent heat-pumping systems used worldwide. Typically, it utilizes the magnetocaloric effect (MCE) to achieve cooling by changing the external magnetic field intensity. However, an alternative approach involves maintaining a fixed field intensity while manipulating its orientation to induce temperature changes, in an effect known as the rotating magnetocaloric effect (RMCE). While the RMCE has been extensively studied in materials with magnetocrystalline anisotropy, its investigation in polycrystalline magnetocaloric samples with asymmetric shapes has been lacking until recently. In this case, the RMCE is induced by the demagnetizing effect, which becomes more pronounced in high aspect-ratio sample geometries exhibiting different effective demagnetizing factors at different orientations, such as in films. In this work, we characterize the conventional and rotational MCE of 40 μm-thick gadolinium films through magnetization and direct temperature measurements. The maximum adiabatic temperature change achieved under a 1 T magnetic field was 2.05 K when the film was oriented in plane with the field and 1.25 K when the film was perpendicular to the magnetic field, corresponding to an adiabatic temperature difference of around 0.8 K which may be induced through magnetic field rotation. Additionally, the maximum adiabatic temperature change upon rotation is shown to exhibit a non-monotonous behaviour with field intensity, displaying a peak value for field intensities around 0.8 T. The high aspect ratio of the Gd film has been demonstrated to considerably enhance the intensity of demagnetizing field-based RMCE compared to bulk samples, paving the way for future research in this emerging field of magnetic refrigeration cooling.

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Strain engineering of magnetocaloric effect in W/Gd/W/MgO structures

Cited by 6 publications

References 31 publications

Магнитные свойства и магнитокалорический эффект в пленках и микропроводах Gd

Магнитные свойства и магнитокалорический эффект в пленках и микропроводах Gd

Magnetic properties and magnetocaloric effect in Gd films and microwires

Direct measurements of the conventional and rotational magnetocaloric effects in Gd thick films

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