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• Explored the potential of Pd-based Heusler alloys as permanent magnets. • Conducted a high-throughput study using the AFLOW database to identify Pd₂YZ Heusler systems. • Utilized density functional theory (DFT) calculations to evaluate magnetocrystalline anisotropy energy (E MCA ) and exchange interactions. • Employed Monte Carlo simulations to analyze temperature-dependent magnetization and determine Curie temperatures (T C). • Identified Pd₂FeNi with an E MCA of 2.4 MJ/m3 and T C of 504 K, and Pd₂FePt with an E MCA of 4.11 MJ/m3 and T C of 463 K. In this work, we have explored the potential of a relatively new class of Pd-based Heusler alloys as permanent magnets. Our approach began with a high-throughput study using the Automatic Flow (AFLOW) electronic structure database to identify Pd₂YZ-type Heusler systems with tetragonal symmetry and high magnetization. For the alloys that passed our initial selection filters, we performed a detailed investigation of their magnetic properties using density functional theory (DFT) calculations. These calculations included assessments of magnetocrystalline anisotropy energy (E MCA ) and exchange interactions. The selected candidates, which met all our criteria, were then subjected to Monte Carlo simulations to analyze the temperature dependence of their magnetization and determine their Curie temperatures (T C). Our results indicate that Pd₂FeNi and Pd₂FePt are promising candidates for permanent magnets. Pd₂FeNi exhibited an E MCA of 2.4 MJ/m3 and a T C of 504 K, while Pd₂FePt showed an E MCA of 4.11 MJ/m3 and a T C of 463 K. Both Curie temperatures are significantly above room temperature by more than 160 K, demonstrating the alloys' potential for high-temperature applications and their overall suitability as efficient, rare earth-free permanent magnets. [ABSTRACT FROM AUTHOR]

[Display omitted] • The negative charge-to-spin conversion in Co 2 FeSi film. • Dresselhaus effect contributed to x-polarized spin current. • Disordered crystalline structure is useful to charge-to-spin conversion efficiency. Recent discoveries of Heusler alloy achieve a strong advantage of the chemically disordered sample in the charge-to-spin conversion and attracted interests for spintronics applications. Here, we observe the negative charge-to-spin conversion in single magnetic layer of Co 2 FeSi/MgO and prove generations of σ y and σ x by spin-torque ferromagnetic resonance (ST-FMR). We also report that the change in charge-to-spin conversion efficiency could be controlled by chemical disordering. Furthermore, the thickness dependents of Co 2 FeSi demonstrated bulk effect is responsible for the generation of spin current. This study contributes to understanding the mechanisms of spin current generation from magnetic full Heusler alloy and also paves the way for the applications of magnetic memory and nonvolatile spin logic technologies. [ABSTRACT FROM AUTHOR]

Full Heusler Co 2 TiSn thin film were grown by DC magnetron sputtering on MgO(001) substrates at temperatures from ambient up to 800°C. The epitaxial films with full Heusler structure and high purity were achieved at 700°C with thickness ranging from ∼ 20 nm to over 1000 nm enabling deeper study of the film growth and the effect of the thickness on film properties. The state of films was investigated by wide range of techniques including atomic force and electron microscopy, X-ray diffraction and photoelectron spectroscopy, magnetometry, and magnetooptical ellipsometry supported by ab initio calculation. Structural diffraction study and magnetooptical spectral analysis reveal that under suitable deposition conditions at 700°C almost perfect L 2 1 ordering can be attained with the [100] film direction along diagonal of cubic MgO substrate. Photoelectron spectroscopy indicated the purity of the deposited material and the fourfold symmetry of deposited films in agreement with XRD. The only downside of these films is a relatively high surface roughness as indicated by SEM and measured by AFM. Saturation magnetization at 10 K and Curie point at 370 K was comparable to bulk. The ordering as well as agreement between experimental and calculated Kerr spectra improve with increasing film thickness. In comparison the properties of Co 2 TiSn are similar to other alloys in the family such as Co 2 FeSi and Co 2 FeGa. • Preparation and systematic study of full Heusler Co 2 TiSn thin films by magnetron sputtering. • Epitaxial cubic films of different thicknesses were prepared only at 700°C. • A nearly perfect L 2 1 order was secured, as confirmed by XRD and MOKE. • Complex ferromagnetic behavior was observed with decreasing temperature. • There is good agreement between ab initio calculations and experimental MOKE spectra. [ABSTRACT FROM AUTHOR]

Exchange bias plays a significant role in the application of spin valves and magnetic sensors. A spontaneous exchange bias field of 0.75 kOe can be observed in the annealed Ni 50 Mn 37 Ga 13 ribbons, while a giant exchange bias field of 6.14 kOe occurs in the quenched samples under field cooling. This is due to the different lattice parameters and microscopic morphology making the annealed and quenched samples, respectively, form superspin glass and spin glass embedded in the antiferromagnetic matrix. The conditions for superspin glass and spin glass to overcome the energy barrier of spin reconfiguration are different, resulting in the difference in exchange bias behavior. This work combines the magnetic properties with the crystal structure and microscopic morphology, providing a method of controlling the glassy state by heat treatments to regulate the exchange bias of Heusler alloys. • The difference in structure and microscopic morphology results in different glassy states. • Spontaneous exchange bias is observed in the annealed sample, while field cooling exchange bias in the quenched sample. • The different exchange bias is caused by superspin glass and spin glass embedded in the antiferromagnetic matrix. [ABSTRACT FROM AUTHOR]

The nature of martensitic phase transitions and its modification as a function of composition and application of magnetic field have been studied in detail for Ni 40 Co 10 Mn 40 Sn 10- x Ga x (x =0, 0.3, 0.4 and 0.5). The phase transition temperature (T M) increases with increasing x. The kinetic arrest (KA) of the austenitic phase has been observed for x =0 and 0.3, which disappeared for x >0.3. The KA results in a decrease in the change of magnetization (Δ M) across T M. However, the isothermal entropy change Δ S varies almost linearly with [d T M /d(μ 0 H)]−1 (field-induced shift in T M) irrespective of the composition variation and thermal cycling. This behavior indicates that the variation of d T M /d(μ 0 H) is the dominant factor determining the magnitude of the Δ S rather than Δ M. Consequently, the effect of KA on ∆ M has a negligible influence on Δ S in the studied Heusler alloys. The reduced field-sensitivity in T M associated with the temperature-induced decrease of magnetization in the ferromagnetic austenitic phase leads to a decrease of the thermal hysteresis and an increase of Δ S. As a result, a large reversible (|Δ S rev |=21 J/kg K for Δ μ 0 H =5 T) has been observed for x =0.5, which exceeds previously reported values for Sn-based Heusler alloys. • Kinetic arrest as often observed in Heusler alloys is expected to have an adverse effect on inverse magnetocaloric effect. • Reduction of the change in magnetization (Δ M) due to the KA will reduce the isothermal entropy change (Δ S). • For a highly field-sensitive martensitic phase transformation the KA has negligible influence on Δ S. [ABSTRACT FROM AUTHOR]

Recently, additive manufacturing (AM) of intrinsically brittle Ni–Mn–X alloys, in which obtaining high-quality powders is imperative, has received widespread attention. Here, a batch weight of about 34 kg Ni–Mn–Sn–Co powder was prepared using industrial gas atomization equipment. To explore the sinterability of the gas-atomized powder and provide a direct comparison in caloric effects for binder-based AM techniques, we sintered Ni–Mn–Sn–Co alloy powder samples at 1173–1273 K for 2–24 h by using a powder metallurgy process with air cooling. The sintered powder samples had a relative density of about 60.3–80.1 %, and 5 M martensite and L 2 1 –ordered austenite were found to coexist at room temperature. For all sintered samples, martensitic transformation temperature width of about 11–17 K and hysteresis of about 21–23 K were obtained, and strong magneto-structural coupling was observed. The magnetocaloric and elastocaloric effects of the sample sintered at 1273 K for 2 h were examined. A magnetic entropy change of about 23.0 J kg−1·K−1 and an adiabatic temperature change (Δ T ad) of −0.97 K were achieved for magnetic fields of 5.0 and 1.25 T, respectively. Furthermore, a Δ T ad of −4.71 K was achieved upon unloading a compressive stress of 350 MPa. These competitive caloric effects in the gas-atomized powder lay the foundation for the AM of Ni–Mn–Sn–Co alloys with complex structures. This study provides a reference for the reliable manufacturing of composition-sensitive Ni–Mn–X Heusler alloys. [ABSTRACT FROM AUTHOR]

In depth understanding of the magnetic, structural and electrical properties of Heusler alloys are crucial to achieve potential applications in spin-based device. Wherein, we report the synthesis of Cr 2 MnAl Heusler alloy nanoparticles (NPs) via co-precipitation method and also demonstrated their transport properties. Interestingly X-ray analysis confirms the cubic phase of the synthesized Heusler alloy NPs and transmission electron microscopy (TEM) analysis reveals that the Cr 2 MnAl as particle size of 10 ± 2 nm. Moreover, this particle size has adverse effect on symmetry of Cr 2 MnAl Heusler alloy due to their higher surface to volume ratio that significantly changes their magnetic and electrical properties. These NPs exhibit soft ferromagnetic properties with a Curie temperature (Tc) of 25 K. Besides, resistivity measurements indicate the semiconducting nature and also we report the observation of anomalous Hall effect. In addition, we support our experimental results by studying the electronic and magnetic properties of alloy using first principle calculations. This density functional theory reveals that Cr 2 MnAl has half metallic characteristics with high spin polarization. In light of above, this material can be used as intermediate layer to decouple the two ferromagnetic layers which acts as spin-polarized carriers in spin-based device. [Display omitted] • Meticulous experimental and DFT studies reveal the structural and magnetic properties of Cr 2 MnAl Heusler alloy. • The magnetic measurement shows that Cr 2 MnAl is a ferromagnetic compound at low temperature. • Analysis of the electrical resistivity of Cr 2 MnAl reveals intriguing semiconducting behavior. [ABSTRACT FROM AUTHOR]

Li-based quaternary Heusler LiHfPdZ (Z = Al, Ga, and In) compounds have been investigated for their electronic properties, structural stability, phonon spectra, and thermoelectric performance. Band structure calculations based on Density Functional Theory, show the indirect semiconductor nature of LiHfPdZ (Z = Al, Ga, and In) compounds with band gaps of 0.73 eV, 0.79 eV, and 0.58 eV, respectively. We obtained flat Hf-5 d bands (without dispersion) in the vicinity of Fermi energy (E F), resulting in a high value of Seebeck coefficient. The positive values of frequencies in the phonon dispersion curve confirm the dynamic stability of these compounds. The computed elastic properties suggested that the studied compounds are mechanically stable. The calculated values of melting points of this compounds are around 1500 ± 300 K, which ensures the stability of these compounds at high temperatures. We obtained a maximum value of the figure of merit 0.72, 0.68 and 0.67 for LiHfPdAl, LiHfPdGa and LiHfPdIn compounds respectively, which is higher than other Li based QH compounds of same kind i.e. LiHfCoSn (0.59) and LiHfCoGe (0.61) obtained by Singh et al. at same temperature. Overall, a comparatively high and stable value of ZT above 600 K is obtained only in LiHfPdAl, which suggests that it is the most suitable candidate as TE material for high-temperature applications. [ABSTRACT FROM AUTHOR]

Co-(V,Nb)–Sn Heusler alloys are studied within the GGA-PBE and hybrid (HSE06) approaches. From HSE06 calculations, the Half-Heusler structures CoVSn and CoNbSn are semiconductors with bandgaps of 1.33eV and 1.50eV, respectively. On the other hand, the Full-Heusler systems Co 2 VSn and Co 2 NbSn have a half-metallic nature and bandgaps of 1.26eV and 0.86eV, respectively. From the analysis of the band structure, high values were found for the effective masses of the structures studied. Furthermore, the results of magnetic moments and chemical bonds are presented, indicating the presence of covalent-polar bonds. Finally, thermoelectric parameters such as Seebeck coefficient (S), electronic conductivity (σ), thermal conductivity (κ), and Figure of Merit (ZT) were determined, including vibrational effects (phonons), thus improving the results that showed good agreement with experimental data. By determining these properties, it is possible to indicate strategies to improve the thermoelectric performance of these materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Introduce classification tasks into GNN to increase prediction accuracy. • Analysis activity with the change of d*, group and period for elements. • Screen high-efficiency catalysts for NRR from 1143 Hassler alloys. • Reveal the geometry that causes N 2 activation and PDS modification. Developing efficient catalysts for nitrogen reduction reaction (NRR) is a meaningful yet challenging endeavor. Here, we employ machine learning to screen efficient Heusler alloy (X 2 YZ) catalysts towards NRR. We incorporate classification tasks into the graph neural network to distinguish between adsorbates and adsorption sites which improving the network's ability to recognize adsorption configurations and enhance its predictive accuracy of adsorption energy simultaneously. Following training on an adsorption energy dataset of 6,000 densityfunctional theory calculations, our model can predict the adsorption energies of critical adsorbates (N 2 , NNH, NH, NH 2 , H) with a mean absolute error of 0.1 eV. Through a multi-criteria screening, we identified a series of Ru-based Heusler catalysts with low limiting potentials and the ability to suppress hydrogen evolution reaction. For example, Ru 2 HfTl exhibits a low limiting potential of −0.32 V. Statistical analysis reveals that the average d -electron of X and Y elements, along with the group number of Z element, can assess the catalyst activity of Heusler alloys. Furthermore, we discover that the unique geometric structure of four-fold hollow sites on the (1 1 0) surface of Heusler alloy can facilitate N 2 activation and alter the potential determining step of NRR. [ABSTRACT FROM AUTHOR]

Materials exhibiting significant polarisation at high spin rates are considered the most promising candidates for spintronic devices. This study investigates the mechanical, optical, spin-polarised electronic structure, magnetism, and thermoelectric properties of CoIrMnX (where X = Sn, Sb). We performed calculations of quaternary Heusler alloys using first-principles calculations. The CoIrMnSn and CoIrMnSb compounds have the most stable Type III crystal structures, according to the calculations performed on the alloys under investigation. We found that the two alloys, CoIrMnSn and CoIrMnSb, possessed a half-metallic ferromagnetic structure, characterised by indirect band gaps of 1.008 eV and 0.806 eV in the predominant spin channels, respectively. Both alloys demonstrate a significant overall magnetic moment of 5 and 6 μβ, respectively. CoIrMnX (where X = Sn, Sb) are ferromagnetic half-metals with 100 percent spin polarisation, according to the results. The results of the elastic constants demonstrate the alloys' mechanical stability. We also investigated optical characteristics such as dielectric function, absorption, reflectance, and optical conductivity. CoIrMnX (where X = Sn and Sb) acts as an efficient absorber in the ultraviolet region and possesses a high refractive index. Alloys exhibit considerable potential as viable candidates for implementation in spintronic devices. The maximum ZT value for CoIrMnSn (CoIrMnSb) is 0.915 (0.6619). To achieve this value, it is necessary to either reduce the charge carrier concentration to n = 0.0812 × 1020 (0.0952 × 1020) cm−3 or the μ to 0.83843 (0.83806) Ryd. Substantially examined materials demonstrate considerable potential for application in the field of thermoelectrics. • The total magnetic moment of Both alloys demonstrate a significant overall magnetic moment of 5 and 6 μβ, respectively. • The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds are mechanically stable. • The ZT of CoIrMnSn (CoIrMnSb) can be increased to a comparatively high value (ZT = 0.915 for CoIrMnSn and ZT = 0.6619 for CoIrMnSb). • These materials could be useful for thermoelectric application. [ABSTRACT FROM AUTHOR]

Direct measurements of the magnetocaloric effect were performed in a Heusler Ni44.4Mn36.2Sn14.9Cu4.5 alloy at cryogenic temperatures in magnetic fields up to 10 T. The maximum value of the inverse magnetocaloric effect in a 10 T field was ∆Tad = –2.7 K in the vicinity of the first-order magnetostructural phase transition at T0 = 117 K. Ab initio and Monte Carlo calculations were performed to discuss the effect of Cu doping into a Ni-Mn-Sn compound on the ground-state structural and magnetic properties. It is shown that with increasing Cu content the martensitic transition temperature decreases and the Curie temperature of austenite slightly increases. In general, the calculated transition temperatures and magnetization values correlated well with the experimental ones.

The structural, magnetocaloric, and magnetic characteristics in Heusler Ni50Mn35In10X5 (X = Ga, Fe, and Al) alloys were examined using X-ray diffraction and field-dependent magnetization measurements. All samples exhibited a mixture structure of cubic L21 and tetragonal L10 and underwent second-order magnetic transitions at TC(Al5) = 220 K, TC(Ga5) = 252 K, and TC(Fe5) = 298 K. The Ga5 alloy exhibited structural change as indicated by a thermal hysteresis that may be seen in the saturation magnetic field in the M(T) dependences. The transition at the TC point from a ferromagnetic to a paramagnetic state caused a drop in magnetization, supported by thermal hysteresis, at a low magnetic field (0.01 T). On the other hand, the Fe5 alloy presented a gradual decrease in magnetization with similar hysteresis behavior, also at a low magnetic field (0.01 T), whereas at 0.1 T of field, no features characteristic of this transition were detected. This could be due to a large difference in the metallic radius of Fe compared to that of In. Otherwise, magnetic investigations demonstrated that the replacement of In with Al may cause the structural transformation temperatures and TC to be shifted to low temperatures. The present results imply that the structural transformation temperatures and the transition itself are highly dependent on chemical composition. Furthermore, under a magnetic field change of 5 T, the maximum magnetic entropy changes of 0.6 J/kg K, 1.4 J/kg K, and 2.71 J/kg K for the Ga5, Fe5, and Al5 alloys, respectively, were determined by their TC. Refrigeration capacity values were found to be 25 J/kg, 74 J/kg, and 98 J/kg at µ0∆H = 5 T. These ribbons are viable candidates for multifunctional applications due to their cheaper cost and their physical characteristics disclosed during the magnetostructural transition, which takes place close to the room temperature.

This present study illustrates the strong effect of geometrical parameters on the magneto-structural properties of Co2MnSi glass-coated microwires prepared using the Taylor–Ulitovsky method. Thus, there are three samples with different geometrical aspect ratios (ρ). The XRD analysis shows a significant change by modifying the aspect ratio; for ρ = 0.42, the main peak with miller indices (220) is recognized as an A2-type disordered cubic structure. For the sample with ρ = 0.46, mixed L21 and B2 cubic structures are observed. Meanwhile, in the sample with a low aspect ratio, ρ = 0.30, the perfect L21 ordered cubic structure is attained. Magnetic characterization has been carried out at a wide range of temperatures and magnetic fields. A significant increase in coercivity and normalized reduced remanence by decreasing the aspect ratio is detected. The change in the magnetic properties is attributed to the modification in the microstructure, which is induced during the fabrication process. Such a dependence on the microstructure and magnetic properties on the ρ-ratio can be associated either with the internal stress distribution and magnitude or with different quenching rates of microwires with different aspect ratios. The current findings demonstrate the tunability of the microstructure and magnetic properties of Co2MnSi-glass-coated microwires simply via a small modification in the geometric properties during the manufacturing process and without excreting any additional post-processing. The variation in the geometric parameters of Co2MnSi glass-coated microwires allows us to tune the magnetic properties and structure, which is essentially advantageous for sensing device development.

The frequency dependence of the nonequilibrium magnetization arising in an electron gas due to spin injection from a half-metallic ferromagnet into a nonmagnetic material is theoretically analyzed. It is shown that high-frequency spin injection gives rise to nonequilibrium magnetization waves, which decay at a length much smaller than the spin diffusion length. This reduces the efficiency of spin injection. [ABSTRACT FROM AUTHOR]

The electronic structure, thermoelectric properties, and thermodynamic entropy of Ti2CrGe-doped Ti0.75HfMo0.25CrGe were investigated using first-principles calculations in combination with the semi-classical Boltzmann transport theory and a common thermodynamic formalism. The band structure was half-metallic with a narrow gap of 0.02 eV in the spin-down channel and metallic character in the spin-up channel. The calculated thermoelectric transport properties revealed that Ti0.75HfMo0.25CrGe exhibited a larger thermoelectric figure of merit ZT with a lower lattice thermal conductivity than its prototype alloy Ti2CrGe. In particular, the entropy of Ti0.75HfMo0.25CrGe was larger than that of Ti2CrGe in the temperature range of 0–1000 K. These results indicate that increasing the entropy is an effective approach for the design of high-performance thermoelectric materials and confirm the entropy "gene" in thermoelectric materials. [ABSTRACT FROM AUTHOR]

Increasing the figure of merit ZT of thermoelectric (TE) alloys is a challenge that is currently attempted through various metallurgy methods, including nanostructuring and dislocation engineering. Microstructures with such a level of complexity raise questions about the mechanical reliability of these new materials. Indeed, despite the values of hardness and elastic modulus known for the clear majority of TE materials, the data on deformation mechanisms are still rare. Focusing on the nanostructured p-type half-Heusler Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, our multi-scale study aims to analyze the deformation mechanisms. Experiments conducted at macro-, meso-, and micro-scale are designed to trigger and assess plasticity mechanisms. Compression testing on bulk samples subject to a confining pressure environment and temperature leads to an exclusive brittle failure. The mixed-mode failure mechanisms involve switching between intra- and inter-granular crack propagation, depending on the grain size met by the crack tip. Cube-corner nanoindentation at meso-scale generates cracks and enables fracture toughness estimation, while TEM analysis of the crack tip area confirms no dislocation activity and 3D-Electron Back Scattered Diffraction technique confirms the mixed crack propagation behavior. At micro-scale, micro-pillar compression stress-strain curves and failure mechanisms are comparable with bulk samples testing analysis. These results can be used to provide design guidelines for more crack-resistant TE alloys. [ABSTRACT FROM AUTHOR]

Increasing the figure of merit ZT of thermoelectric (TE) alloys is a challenge that is currently attempted through various metallurgy methods, including nanostructuring and dislocation engineering. Microstructures with such a level of complexity raise questions about the mechanical reliability of these new materials. Indeed, despite the values of hardness and elastic modulus known for the clear majority of TE materials, the data on deformation mechanisms are still rare. Focusing on the nanostructured p-type half-Heusler Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, our multi-scale study aims to analyze the deformation mechanisms. Experiments conducted at macro-, meso-, and micro-scale are designed to trigger and assess plasticity mechanisms. Compression testing on bulk samples subject to a confining pressure environment and temperature leads to an exclusive brittle failure. The mixed-mode failure mechanisms involve switching between intra- and inter-granular crack propagation, depending on the grain size met by the crack tip. Cube-corner nanoindentation at meso-scale generates cracks and enables fracture toughness estimation, while TEM analysis of the crack tip area confirms no dislocation activity and 3D-Electron Back Scattered Diffraction technique confirms the mixed crack propagation behavior. At micro-scale, micro-pillar compression stress-strain curves and failure mechanisms are comparable with bulk samples testing analysis. These results can be used to provide design guidelines for more crack-resistant TE alloys. [ABSTRACT FROM AUTHOR]

The magnetic properties and thermoelectric properties of two Heusler compounds, the Fe2CoAl and Fe2NiAl phases, were investigated. The Fe2CoAl and Fe2NiAl compounds were ferromagnetic at room temperature and showed high saturation magnetization of 135 emu/g for the Fe2CoAl compound and 116 emu/g for the Fe2NiAl compound. Both compounds exhibited a high Curie temperature of around 1000 K. It was found that these compounds showed low electrical resistivity of less than 6.0 μΩm at room temperature. Thermoelectric measurements revealed that these compounds had negative Seebeck coefficients of −20 μV/K for the Fe2CoAl compound and −15 μV/K for the Fe2NiAl compound at room temperature. [ABSTRACT FROM AUTHOR]

A half-Heusler material FeNb0.8Ti0.2Sb has been identified as a promising thermoelectric material due to its excellent thermoelectric performance at high temperatures. The origin of the efficient thermoelectric performance is investigated through a series of low-temperature (2–400 K) measurements. The high data coherence of the low and high temperatures is observed. An optimal and nearly temperature-independent carrier concentration is identified, which is ideal for the power factor. The obtained single type of hole carrier is also beneficial to the large Seebeck coefficient. The electronic thermal conductivity is found to be comparable to the lattice thermal conductivity and becomes the dominant component above 200 K. These findings again indicate that electron scattering plays a key role in the electrical and thermal transport properties. The dimensionless figure of merit is thus mainly governed by the electronic properties. These effects obtained at low temperatures with the avoidance of possible thermal fluctuations together offer the physical origin for the excellent thermoelectric performance in this material. [ABSTRACT FROM AUTHOR]

Electrical transport studies of half-Heusler (HH)-based composites (TmNiSb)1−x(TmNiSn)x were carried out in a wide temperature range aimed at searching for possible enhancement in the thermoelectric power factor (PF) over that observed in the parent compound TmNiSb. The best thermoelectric performance was found in the sample with x = 0.25, which showed PF = 1.3 × 10−3 W/mK at 1000 K, i.e., about 70% larger than PF of TmNiSb at the same temperature. The PF improvement was obtained due to the formation in the composite system of a microstructure in which semiconducting-like particles of TmNiSb were covered with a metallic layer of TmNiSn. The largest Seebeck coefficient S =137 μV/K was observed for HH alloy TmNiSb at 560 K. In turn, TmNiSn showed a metallic behavior with small negative thermoelectric power (S = –2.6 μV/K). [ABSTRACT FROM AUTHOR]

An investigation on the relationship between magnetostriction and magnetization by means of the self-consistent renormalization (SCR) theory of an itinerant ferromagnet was performed for Ni2MnGa alloy. The magnetization results at the Curie temperature TC suggest that the critical index δ of H ∝ Mδ is 4.7–5.0, and this confirms Takahashi's spin fluctuation theory and the result of Nishihara et al. As a result, at TC, the relation between magnetostriction and M2 deviates from proportionality and the magnetostriction is proportional to M4. At TC, the plot of ΔL/L vs M4 crossed the point of origin. This result is in accordance with Takahashi's spin fluctuation theory. [ABSTRACT FROM AUTHOR]

Herein, we achieved a large reversible room temperature magneto-caloric effect (MCE) through synergic tuning of martensitic transformation (MT) temperatures and transition entropy change (ΔStr) via micro-alloying with transition metals (Ti, V, and Cr) in Ni45Co5Mn40Sn10 meta-magnetic Heusler alloys (MHAs). By the minor addition of TM, MT temperatures were brought down to below room temperature and ΔStr was reduced while maintaining narrow MT temperature range (ΔT) and large difference in magnetization (ΔM) of Ni45Co5Mn40Sn10 MHA. In particular, Ni43.8Cr1.2Co5Mn40Sn10 MHA exhibited a very large reversible room temperature magnetic entropy change (ΔSM) of 24.5 J/kg.K with a broad operating temperature window of ~11K at 5 T. Indeed, the MHA exhibited a very effective refrigeration capacity (RCeff) of 276 J/kg for 5 T, which is the largest value among the reported Ni-Mn-based MHAs. The decrease of ΔStr reduces the magnetic field required for completely reversible MT and accelerates the saturation of ΔSM, which leads to maximum RCeff value in the composition of MHA. Thus, we can conclude that smaller ΔStr with narrow ΔT and large ΔM is a key variable to develop MHA with reversible MCE under low magnetic field, which will ultimately give us a guideline for the tailor-made design of highperformance magneto-caloric materials. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of a new series CoRhZrZ quaternary Heusler were investigated theoretically by using the density of function theory calculation. All the compounds were found to be stable at the ferromagnetic phase. The magnetic moments of the compound show a positive value ranging from 1 to 2 μB. In addition, the electronic structure of CoRhZrSi shows a large value of the half‐metallic band gap of 0.34 eV. This reflects the high thermal stability of the compound at high temperatures and allowing for a wide range of applications of this material in varying domains, especially those requiring high thermal stability such as the oil and gas sectors, geological applications, and space applications. [ABSTRACT FROM AUTHOR]

Colossal magnetoresistance materials have demonstrated large changes in resistance in the presence of magnetic fields. In the current work, a group of such materials, with the compositional formula La0.67Ba0.33MnO3 and 10% Fe, Co, Ni, Zn doped La0.67Ba0.33MnO3 have been prepared by conventional solid-state method. Structural analysis has been carried out by X-Ray diffraction method followed by Rietveld analysis. Magnetic transition between ferromagnetism to paramagnetism has been observed from the magnetic characterizations. Parameters such as Curie temperature (θP) and effective magnetic moment (µeff) are obtained from susceptibility analysis subject to Curie–Weiss law. Furthermore, magnetocaloric nature of the samples is examined from the M-H isotherms. Using Maxwell's relations, isothermal entropy change, ∆Smax are determined to check whether the prepared samples can be used for magnetic refrigeration around the room temperature. [ABSTRACT FROM AUTHOR]

Colossal magnetoresistance materials have demonstrated large changes in resistance in the presence of magnetic fields. In the current work, a group of such materials, with the compositional formula La0.67Ba0.33MnO3 and 10% Fe, Co, Ni, Zn doped La0.67Ba0.33MnO3 have been prepared by conventional solid-state method. Structural analysis has been carried out by X-Ray diffraction method followed by Rietveld analysis. Magnetic transition between ferromagnetism to paramagnetism has been observed from the magnetic characterizations. Parameters such as Curie temperature (θP) and effective magnetic moment (µeff) are obtained from susceptibility analysis subject to Curie–Weiss law. Furthermore, magnetocaloric nature of the samples is examined from the M-H isotherms. Using Maxwell's relations, isothermal entropy change, ∆Smax are determined to check whether the prepared samples can be used for magnetic refrigeration around the room temperature. [ABSTRACT FROM AUTHOR]

The configurations of L21 and XA for Heusler alloys Mn2OsSb and Mn2PtSb were studied and the corresponding cubic phase equilibrium lattice constants were determined. The results show that the XA-type Mn2OsSb and L21-type Mn2PtSb are their cubic ground states, repectively. The calculated elastic constants and drawn three-dimensional Young's modulus indicate these cubic phase has stable mechanical properties and elastic anisotropy. When the tetragonal deformation is considered, it is found that the tetragonal L21-type structure of Mn2PtSb can further reduce the total energy with respect to the cubic phase, while XA-type structure of Mn2OsSb is still the most stable configuration. The electronic structures show that the cubic XA configuration of Mn2OsSb of present half-metallic characteristics, and the total magnetic moment per molecular unit meets the Slater–Pauling rule. [ABSTRACT FROM AUTHOR]

Half-Heusler alloy topological semimetal YPtBi is a promising candidate for an efficient spin source material having both large spin Hall angle θSH and high thermal stability. However, high-quality YPtBi thin films with low bulk carrier density are usually grown at 600 °C, which exceeds the limitation of 400 °C for back end of line (BEOL) process. Here, we investigate the crystallinity and spin Hall effect of YPtBi thin films grown at lower growth temperature down to 300 °C. Although both effective spin Hall angle and spin Hall conductivity degraded with lowering the growth temperature to 300 °C due to degradation of the interfacial spin transparency, they were recovered by reducing the sputtering Ar gas pressure. We achieved a giant θSH up to 7.8 and demonstrated efficient spin–orbit torque magnetization switching by ultralow current density of ∼105 A/cm2 in YPtBi grown at 300 °C with the Ar gas pressure of 1 Pa. Our results provide the recipe to achieve giant θSH in YPtBi grown at lower growth temperature suitable for BEOL process. [ABSTRACT FROM AUTHOR]

This study aims to investigate the magnetocaloric properties of a La0.77Mg0.23-x□xMnO3 (0 ≤ × ≤ 0.2) series elaborated using a solid-state method and published in Alloys Compd., 738, 2018, 528–539. In our crystallographic study, our compounds display an orthorhombic structure with Pnma group space. The Raman analysis confirms the structure formation of the compounds. The magnetic measurements show that all samples displayed a second-order magnetic phase transition from ferromagnetic to paramagnetic state, which is also supported by Landau's theory. The magnetic entropy change (ΔSM) and the relative cooling power (RCP) of La0.77-x□xMg0.23MnO3 (0 ≤ × ≤ 0.2) samples are determined from their measured magnetization data as a function of the magnetic applied field. At μ0H = 5 T, the maximum value of the magnetic entropy change ΔSmax was found to decrease from 2.59 J/kg.K for x = 0.0 to 0.38 J/kg.K for x = 0.2. Our results indicate that the optimum magnetocaloric effect at H = 5 T occurs for the composition x = 0.0, which makes it a promising material in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT)–based calculations are performed to investigate structural, electronic, and thermoelectric properties of XXYIn (X = Fe, Ru; Y = Nb, V) full and quaternary Heusler alloys using Quantum ESPRESSO package. We have calculated transport properties using semi-classical Boltzmann theory with constant relaxation time and n-type charge carrier concentrations 1021 and 1022 cm−3. First, we investigate the stability of alloys by computing their mechanical and elastic properties, which indicate that all alloys are mechanically stable. To compute lattice thermal conductivity, we have used Callaway's model. We find that Ru2VIn has lowest value of thermal conductivity compared to other compounds. FeRuNbIn has a maximum value of Seebeck coefficient (S) at around 400 K and carrier concentration 1021 cm−3, while Fe2NbIn and Fe2VIn have the largest values of S at the other concentrations, respectively. Ru2NbIn has the largest value of power factor at 1300 K in 1022 cm−3. Largest values of figure of merit ( ZT ) are 0.11 at 600 K for 1021 cm−3 concentration and 0.22 at 1300 K for 1022 cm−3 concentration for FeRuNbIn alloy. [ABSTRACT FROM AUTHOR]

A high-saturation magnetization CoFe layer was electroplated onto Ni50Mn33In16Cr1 alloy using a magnetic field assistance electroplating bath. This CoFe-coated alloy can function as an active magnetic regenerator owing to its magnetocaloric effect. The CoFe coating layer did not affect the entropy change calculated from the isothermal magnetization of the alloy, but it significantly affected the temperature variation of the alloy by changing the externally applied magnetic field. The temperature change of the CoFe-coated alloy increases with increasing CoFe coating times. By comparing with the as-sintered alloy, a maximum increase of 150% in temperature change can be observed in the alloy coated with CoFe for 2 h. [ABSTRACT FROM AUTHOR]

Heusler materials have shown a ground-breaking role in material research because of their widespread applicability in modern technologies and multi-dimensional properties. In this study, the pressure effects on the structural, electronic, and magnetic properties of Mn2YAN (Y = Ru, Rh, and Pd) Heusler alloys are investigated. This study is carried out by employing a state-of-the-art first-principles computational approach called "full potential (FP) linearized (L) augmented plane wave plus local orbital (APW + lo)" as designed using density functional theory (DFT), and executed in WIEN2k computational code. The computed results for the lattice constants have been found to be in fairly good agreement with previously reported results in the literature. The results show that the Mn2RuSn, Mn2RhSn, and Mn2PdSn compounds are stable in the Hg2CuTi-type structure. Furthermore, under the pressure effect, the Mn2RuSn, Mn2RhSn, and Mn2PdSn compounds become half-metals at about 10 GPa, 10 GPa, and 20 GPa, respectively. [ABSTRACT FROM AUTHOR]

The La0.65Ca0.35-xKxMn0.95Ni0.05O3 (x = 0, 0.05, 0.10, 0.15, 0.20) series of specimens were successfully synthesized by the Pechini sol–gel method. The obtained samples were all single-phase perovskite structures. With the increase of K+ doping amount, the TC of the samples increased gradually and can be adjusted to around room temperature slowly. The samples exhibited a second-order magnetic phase transition near the TC. Under the applied magnetic field of 5 T, the ΔSM of the sample decreased with the increase of doping ion content, the half-peak width of the ΔSM increased instead. When the doping amount was 0.15, the RCP of the samples reached the largest. It is demonstrated that moderate doping can enhance the magnetocaloric effect of the sample. Under the applied magnetic field of 5 T, the RCP of the La0.65Ca0.20K0.15Mn0.95Ni0.05O3 sample is 317.77 J·kg−1. These results indicated the La0.65Ca0.35-xKxMn0.95Ni0.05O3 compound have the potential to be a material for magnetic refrigeration. [ABSTRACT FROM AUTHOR]

In this work, the structural, magnetic, thermal, and transport properties of the arc-melted polycrystalline Heusler alloy Co2Ti1.5Sn0.5 are investigated. The alloy crystallizes in an L21 structure with a space group of Fm-3m. The magnetic properties of the alloy depict its antiferromagnetic nature and the alloy exhibits magnetic ordering around Neel Temperature TN = 8.5 K. The effective magnetic moment value obtained from the Curie –Weiss law suggests that the cobalt atom in the alloy is in the low-spin state. From the heat capacity studies, the Sommerfeld coefficient and Debye temperature were determined. In addition, electrical resistivity shows a linear response with increasing temperature, indicating the metallic nature of the alloy. [ABSTRACT FROM AUTHOR]

Heusler alloy with an atomic composition of Ni51.82Mn32.37In15.81 was prepared by melt spinning from arc-melted ingots. X-ray diffraction, scanning electron microscopy and magnetic measurements were used to study the structural, microstructural and magnetic properties. The crystal structure consists of a mixture of B 2 austenite (~50%) and 14 M martensite (~50%). The alloy undergoes a second order magnetic transition at a Curie temperature of T c A = 194.2   K. The hysteresis loop reveals the occurrence of exchange bias phenomenon at room temperature. The critical exponents β , γ and δ were estimated using modified Arrott plots, Kouvel–Fisher curves and critical isothermal analysis. The respective values are β = 0.500 ± 0.015 , γ = 1.282 ± 0.055 and δ = 3.003 ± 0.002 . The critical behaviour in ribbons is governed by the mean field model with a dominated long-range order of ferromagnetic interactions. The maximum entropy change, ∆ S M m a x , for an applied magnetic field of 5 T reaches an absolute value of 0.92 J/kg·K. The experimental results of entropy changes are in good agreement with those calculated using Landau theory. [ABSTRACT FROM AUTHOR]

In this paper, structural, elastic, electronic and magnetic properties of half-Heusler XSrC (X = Li and Na) compounds have been investigated utilizing full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). For exchange-correlation potentials, the generalized gradient approximation (GGA) has been used. The calculated cohesive and formation energy values showed that these compounds can be experimentally synthesized. The elastic properties were analyzed in detail and reveal that LiSrC and NaSrC compounds are mechanically stable. The spin-polarized band structure and density of states illustrate that LisrC and NaSrC alloys have a half metallic character. The total magnetic moment is 1 μ B per formula unit that confirms the half metallic behavior and follows the Slater-Pauling rule M T = (8 − Z tot ) μ B . For half-Heusler XSrC (X = Li and Na) compounds, there are no available experimental or theoretical studies, our calculations are considered as first predictions. [ABSTRACT FROM AUTHOR]

The density functional theory was used to explore the structural, electronic, dynamical, and thermoelectric properties of a VIrSi half-Heulser (HH) alloy. The minimum lattice constant of 5.69 (Å) was obtained for VIrSi alloy. The band structure and the projected density of states for this HH alloy were calculated, and the gap between the valence and conduction bands was noted to be 0.2 eV. In addition, the quasi-harmonic approximation was used to predict the dynamical stability of the VIrSi HH alloy. At 300 K, the Seebeck coefficient of 370 and −270 μ V.K − 1 , respectively, was achieved for the p and n-type doping. From the power factor result, the highest peak of 18 × 10 11 W/cm.K 2 is obtained in the n-type doping. The Figure of Merit (ZT) result revealed that VIrSi alloy possesses a high ZT at room temperature, which would make VIrSi alloy applicable for thermoelectric performance. [ABSTRACT FROM AUTHOR]

We study the effect of annealing and the applied magnetic field from 50 Oe to 20 kOe on the magneto-structural behavior of Ni2FeSi-based Heusler microwires fabricated by using Taylor-Ulitovsky technique. Using the XRD analysis, a strong effect of annealing, manifested as the development of the crystallization process, was observed. The average grain size and crystalline phase content of annealed sample increase from 21.3 nm and 34% to 32.8 nm and 79%, respectively, as-compared to the as-prepared one. In addition, upon annealing, phase transforms into a monoclinic martensitic structure with a modulation of 10 M, which cannot be found in the as-prepared sample. Concerning the magnetic properties, both samples show ferromagnetic behavior below and above the room temperature, where the Curie temperature of Ni2FeSi is higher than the room temperature. The induced secondary phases have a noticeable effect on the magnetic behavior of the annealed sample, where a high normalized saturation magnetization (NMs) and low normalized reduced remenance (Mr = M/M5K), compared to the as-prepared have been detected. Additionally, the coercivity of annealed sample shows one flipping point at 155 K where its behavior changes with temperature. Meanwhile, the as-prepared sample show two flipped point at 205 K and 55 K. A mismatch between field cooling (FC) and field heating (FH) magnetization curves with temperature has been detected for annealed sample at low applied magnetic field. The difference in magnetic and structure behavior of Ni2FeSi microwires sample is discussed considering the effect of induced internal stresses by the presence of a glass coating and the recrystallization and stresses relaxation upon annealing. [ABSTRACT FROM AUTHOR]

We present calculations based on density-functional theory with improved exchange-correlation approaches to investigate the electronic structure of Ni 2 MnGa magnetic shape memory alloy prototype. We study the effects of hybrid functionals as well as a Hubbard-like correction parameter U on the structural, electronic and magnetic properties of the alloy. We show that the previously successful application of U on Mn should be extended by including U on Ni to describe the d localized electrons more accurately and in better agreement with experiments. The bonding interactions within this intermetallic alloy are analysed including the role of non-transition metal. We found that the strongest and most stabilizing bond is formed between the Ga–Ni pairs due to the delocalized s–s and p–s orbital hybridization. Our findings suggest that minimization of the over-delocalization error introduced by standard semi-local exchange-correlation functionals leads to a better description of the Ni 2 MnGa alloy. Furthermore we propose that the experimental total magnetic moment of Ni–Mn–Ga alloys could be increased after carefully selected heat treatment procedures. [ABSTRACT FROM AUTHOR]

The effect of hydrostatic pressure on the martensitic transformation and magnetocaloric properties of MnNi0.88GeV0.12 alloy is studied in detail. X‐ray diffraction at room temperature shows that the alloy has a single hexagonal Ni2In‐type structure. The phase transition temperature moves to the low‐temperature region with the increase in hydrostatic pressure. Under the external magnetic field of 15 kOe, the hydrostatic pressure driving rates dTM/dP and dTA/dP are 60.25 and 65.25 K GPa−1, respectively, which indicate that the applied pressure expands the working temperature range of magnetic refrigeration. A magnetic entropy change ΔS of −4.8 J kg−1 K−1 is obtained in the external magnetic field of 15 kOe under ambient pressure. The peak value of |ΔS| is increased to 5.6 J kg−1 K−1 under hydrostatic pressure, which is closely related to the structural change of the alloy. [ABSTRACT FROM AUTHOR]

Here, we report synthesis and investigations of bulk and nano-sized La(0.7−x)EuxBa0.3MnO3 (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La(0.7−x)EuxBa0.3MnO3, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La0.7Ba0.3MnO3, has Curie temperature TC = 340 K. The magnetocaloric effect is at its maximum around TC. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40–80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition TC = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower TC values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained. [ABSTRACT FROM AUTHOR]

The structural, elastic, electrical, and magnetic properties of the novel d0 half-Heusler alloy CsBaC were studied using first-principles calculations based on the density functional theory (DFT). The generalized gradient approximation suggested by Perdew–Burke–Ernzerhof is used to treat the exchange–correlation functional (GGA-PBE). To improve the calculations of the electronic structure as well as magnetic characteristics, the Tran-Blaha modified Becke-Johnson (TB-mBJ) exchange potential is used, which can precisely calculate the energy gap of solids. According to our findings, the examined alloy is energetically stable in the type-1 phase with cohesive negative energy and formation energy. It is possible to predict that the researched CsBaC compound can be produced experimentally due to its negative formation energy. The studied compound find to be half-metallic ferromagnet with a total magnetic moment of 1.00008 μB per formula unit, which agrees well with the Slater-Pauling rule (Mtot = (8 − Ztot) μB). Our computations depict that CsBaC has majority band gaps of 0.58 eV (1.83 eV) with half-metallic gap of 0.21 eV (0.90 eV), respectively, by GGA-PBE and TB-mBJ. The obtained results also reveal that the CsBaC compound can be considered half-metallic ferromagnets for lattice parameters range, making them likely candidates for potential applications in spintronics and solar cells. [ABSTRACT FROM AUTHOR]

The effects of V addition on the structural, magnetic, and magnetocaloric properties in Ni49-xVxMn37Sn12B2 (x = 0, 1, 2, and 3) alloys were investigated. XRD analyses performed at room temperature showed that the main sample was in martensite phase, while x = 3 sample was in L21 structure which is attributed to austenite phase. The samples exhibited a first-order structural transformation from austenite phase to martensite phase. The martensitic transformation (MT) temperature was reduced by increasing the amount of V. Besides, V doping caused an increase in magnetization. Although antiferromagnetic interactions arising from Mn–Mn couplings were effective at low temperatures, they vanished above the blocking temperature. Magnetic entropy change (ΔSM) of the samples was estimated using the Maxwell equation from isothermal magnetization curves. An inverse magnetocaloric effect was observed around the MT interval and ΔSM was significantly improved with increasing V content and applied magnetic field. Maximum refrigerant capacity (RC), which is one of the quality parameters for characterizing a magnetic refrigerant, was determined as 96.7 J/kg for x = 3 samples (ΔH = 5 T). [ABSTRACT FROM AUTHOR]

Due to growing interest to predict and design new potential Heusler alloys by using theoretical calculations and highly functional software, research on Heusler alloys has taken great attention. From this point of view, this study considers investigation of X2MgAl (X = Sc, Ti and Y) alloys by adopting first principles calculations for the first time. A thorough investigation has been carried out to reveal these alloys' mechanical, electronic, vibrational and thermodynamic properties. It is seen that all alloys have negative formation energies as − 0.278 eV/atom for Sc2MgAl, − 0.058 eV/atom for Ti2MgAl and − 0.304 eV/atom for Y2MgAl which indicates synthesisability and thermodynamic stability. Mechanical stability investigations based on the elastic constants of alloys have revealed that all alloys are mechanically stable. The electronic band structures of alloys demonstrate that X2MgAl (X = Sc, Ti and Y) alloys are metallic since there is no energy gap near the Fermi level. Cauchy's pressures of alloys are found as − 17.791 GPa for Sc2MgAl, 31.404 GPa for Ti2MgAl and − 11.759 GPa for Y2MgAl which displays that Sc2MgAl and Y2MgAl are brittle and Ti2MgAl is ductile. The phonon dispersion curves are calculated along the lines of high symmetry within the first Brillouin region. Phonon frequencies are completely positive in the full Brillouin region, which proves the dynamic stability of the L21 phases of these alloys. Several thermodynamic properties such as Debye entropy, temperature and vibrational free energy are also computed and analysed. Debye entropies of alloys follow Ti2MgAl > Y2MgAl > Sc2MgAl relationship. [ABSTRACT FROM AUTHOR]

In this study, effects of different pressing processes on the microstructure and thermoelectric properties of TiNiSn1-xTex Half-Heusler alloy prepared by microwave method were investigated. TiNiSn1-xTex Half-Heusler alloys prepared by microwave synthesis-warm pressing-microwave sintering process had relatively higher density than those of samples prepared by microwave synthesis-cold pressing-microwave sintering (MCM) process. The XRD results showed that the diffraction peaks of TiNiSn1-xTex samples slightly shifted to the large angle direction because of the Te substitution on the Sn sites, and the intensity of impurity peak decreased after microwave sintering. Although the density of TiNiSn1-xTex samples prepared by MCM process was lower, the thermoelectric performance of TiNiSn0.99Te0.01 sample was significantly improved, which resulted from the decrease of resistivity and thermal conductivity due to the Te-doping. The thermal conductivity of TiNiSn0.99Te0.01 was within 1.21–1.61 Wm - 1 K - 1 over the whole temperature range, and its thermoelectric figure of merit ZT was the best. [ABSTRACT FROM AUTHOR]

Rare earth (RE)-based alloys or compounds with considerable cryogenic magnetocaloric effect (MCE) have been extensively investigated recently due to their potential applications in the field of cryogenic magnetic refrigeration. Herein, three RE-based compounds of Sr2RETaO6 (RE = Dy, Ho, and Er) were fabricated and investigated in detail with regard to their structural, magnetic, and magnetocaloric properties. All the present Sr2RETaO6 compounds crystalize in the double perovskite (DP)-type structure (P21/c space group) with the B site occupied by RE elementals and order magnetically at low temperature. Additionally, considerable cryogenic MCE has been observed in Sr2RETaO6 DP compounds, which were confirmed by a series of MCE merits, including the maximum magnetic entropy change, temperature-averaged entropy change (3 K lift), and relative cooling power. The corresponding values with field change ΔH = 0–70 kOe are found to be 10.55 J·(kgK)−1, 10.18 J·(kgK)−1, 144.67 J·kg−1, to be 7.49 J·(kgK)−1, 7.42 J·(kgK)−1, 198.53 J·kg−1, and to be 8.56 J·(kgK)−1, 8.52 J·(kgK)−1, 142.73 J·kg−1 for Sr2DyTaO6, Sr2HoTaO6 and Sr2ErTaO6 compounds, respectively. These obtained values for the present Sr2RETaO6 compounds are close to most of the recently reported RE-based MCE materials. [ABSTRACT FROM AUTHOR]

Abstract—In the Ni47Mn42In11 and Ni43Со4Mn42In11 alloys, structural and magnetic phase transformations were studied by the magnetometry, dilatometry, and structural analysis. The temperatures of structural and magnetic transitions of the Ni43Со4Mn42In11 alloy have been determined. It has been shown that cobalt doping significantly increases the difference between the martensitic transformation temperature and Curie temperature. It has been found that in this alloy the martensitic transformation is accompanied by jumps in the temperature dependences of linear thermal expansion. [ABSTRACT FROM AUTHOR]

In this work, we have successfully fabricated nanocrystalline Co2MnSi Heusler alloy glass-coated microwires with a metallic nucleus diameter (dnuclei) 10.2 ± 0.1 μm and total diameter 22.2 ± 0.1 μm by the Taylor–Ulitovsky technique for the first time. Magnetic and structural investigations have been performed to clarify the basic magneto-structural properties of the Co2MnSi glass-coated microwires. XRD showed a well-defined crystalline structure with a lattice parameter a = 5.62 Å. The room temperature magnetic behavior showed a strong in-plane magnetocrystalline anisotropy parallel to the microwire axis. The M-H loops showed unique thermal stability with temperature where the coercivity (Hc) and normalized magnetic remanence exhibited roughly stable tendency with temperature. Moreover, quite soft magnetic behavior has been observed with values of coercivity of the order of Hc = 7 ± 2 Oe. Zero field cooling and field cooling (ZFC-FC) magnetization curves displayed notable irreversible magnetic dependence, where a blocking temperature (TB = 150 K) has been observed. The internal stresses generated during the fabrication process induced a different magnetic phase and is responsible for the irreversibility behavior. Moreover, high Curie temperature has been reported (Tc ≈ 985 K) with unique magnetic behavior at a wide range of temperature and magnetic fields, making it a promising candidate in magnetic sensing and spintronic applications. [ABSTRACT FROM AUTHOR]

The high-temperature tensile deformation behaviors of the recrystallization annealed Al7(CoNiV)93 medium entropy alloy with a duplex hierarchical microstructure of face-centered cubic (fcc) and ordered body-centered cubic L21 Heusler-type grains were investigated. The alloy showed a remarkably high tensile strength of ∼1.1 GPa and good ductility of ∼17% at 923 K due to a good strain hardening capacity of 60 MPa. At 1073 K, the highest fracture elongation of ∼270% was displayed at a strain rate of 10−3 s−1. The strain rate sensitivity was estimated to be about 0.32, which is typical of alloys that show this quasi-superplastic elongation. The activation energy was also estimated to be ∼421 kJ/mol. With deformation at 1073 K at a strain rate of 10−3 s−1, the duplex microstructure transformed into a refined triplex fcc-L21-σ equiaxed microstructure. The development of the triplex equiaxed microstructure resulted from dynamic recrystallization (DRX), which assisted in the maximum superplastic-like elongation of 270%. The inability of the alloy to access true superplasticity was attributed to immense cavitation due to the high amount of the brittle σ phase, which served as de-cohesion sites for the early fracture of the sample. However, the observed quasi-superplasticity could still be useful in superplastic forming operations. [ABSTRACT FROM AUTHOR]

First-principles calculations of the stability, electronic, and magnetic properties of full-Heusler compound V2FeSi and Fe2VSi in regular ( L 2 1 ) and inverse ( X A ) structures have been performed using density functional theory within an SCAN meta-GGA functional. It is found that the X A crystal lattice is energetically more favorable for V2FeSi, while Fe2VSi forms the L 2 1 structure. In both cases, the electronic structure of the energetically stable modifications corresponds to half-metallic ferrimagnets. Magnetic properties of energetically favorable structures obey the Slater–Pauling rule. All considered properties of the studied structures are explained within the crystal orbital Hamilton population analysis. [ABSTRACT FROM AUTHOR]