Thermal properties and microstructure of bulk nanocrystalline Gd material

Zeng, Hong; Kuang, Chunjiang; Zhang, Jiuxing; Yue, Ming

doi:10.1007/s10853-009-3769-0

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…The deposition was performed at room temperature under 3 mTorr Ar with a base pressure of 3 Â 10 À7 Torr. Similarly prepared Gd films capped with Ta exhibited a resistivity q Gd ¼ 525.0 lX cm, which is somewhat higher but reasonably consistent with prior measurements 39 of nanocrystalline Gd, indicating minimal oxidation of the Gd metal.…”

supporting

confidence: 86%

Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

Ueda

Pai

Tan

et al. 2016

Applied Physics Letters

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We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

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confidence: 86%

Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

Ueda

Pai

Tan

et al. 2016

Applied Physics Letters

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“…The broadening of DS peaks revealed in the asconsolidated samples in comparison with the coarsegrained bulk Gd metal, can be at least partially, attributed to the structural disorder due to the significantly increased total grain boundary volume. It is well seen in the TEM, especially the HRTEM (Zeng et al 2009), that the grain Fig. 4 Arrott plots of the nanocrystalline bulk Gd metals around the Curie temperature: a the as-consolidated at 280°C, b the asconsolidated at 700°C and c raw material boundary microstructure in the nanocrystalline Gd is like the disordered amorphous phase state, being very different from that in the crystal grain.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental details on the preparation and characterization of the consolidated bulk of the pure rare earth Gd metals have been published elsewhere (Zeng et al 2009). …”

Section: Methodsmentioning

confidence: 99%

Magnetic entropy change in bulk nanocrystalline Gd metals

et al. 2011

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The magnetocaloric properties of the asconsolidated nanocrystalline and coarse-grained gadolinium metals were studied in the present work. With the decrease of Gd grains from micrometer to nanometer range, magnetic entropy change drops surprising from 10.07 to 4.47 J kg -1 K -1 at a magnetic-field change of 5 T, and their resultant magnetic entropy change uniformly peaks at 294, 290, and 288 K, respectively, corresponding to the magnetic transition temperature of the three samples. The Curie temperature T C of the nanocrystalline Gd shifts by more than 6 K below that of coarse-grained Gd sample. However, the values of magnetic entropy change of the nanocrystalline metals exhibit a more constant tendency compared with the coarse-grained sample. The Arrott plots indicate the second-order character of magnetic phase transition still in the nanocrystalline Gd metals. The refrigerant capacity calculated is also used to evaluate material refrigeration capacity.

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“…, the fraction of grain boundaries, was found to critically influence the physico-chemical properties of bulk Gd metal [ 23 , 24 ]. With a decrease in the grain size from the micrometer to the nanometer range, (i) the Curie temperature decreased and exhibited a broader shape in DSC (Differential Scanning Calorimetry) heating curves [ 23 ] (ii) the room-temperature electrical resistivity was found to increase, while the low-temperature resistivity increased remarkably [ 24 ]. The oxidized surface layer of a ternary Gd alloy was not found to significantly affect the bulk magnetocaloric performance of the material [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Microstructural Anisotropy of Magnetocaloric Gadolinium Cylinders: Effect on the Mechanical Properties of the Material

et al. 2016

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The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium- and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces.

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Thermal properties and microstructure of bulk nanocrystalline Gd material

Cited by 6 publications

References 18 publications

Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

Magnetic entropy change in bulk nanocrystalline Gd metals

Microstructural Anisotropy of Magnetocaloric Gadolinium Cylinders: Effect on the Mechanical Properties of the Material

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