Half-metallic ferromagnetic (HMF) materials show high spin polarization and are therefore interesting to researchers due to their possible applications in spintronic devices. In these materials, while one spin sub band has a finite density of states at the Fermi level, the other sub band has a gap. Because of their high Curie temperature (TC) and tunable electronic structure, HMF Heusler alloys have a special importance among the HMF materials. Full Heusler alloys with the stoichiometric composition X2YZ (where X and Y are the transition metals and Z is a sp element) have the cubic L21 structure with four interpenetrating fcc sublattices. When each of these four fcc sublattices is occupied by different atoms (XX′YZ), a quaternary Heusler structure with different structural symmetries (space group F-43m, #216) is obtained. Recently, these equiatomic quaternary Heusler alloys (EQHAs) with 1:1:1:1 stoichiometry have attracted a lot of attention due to their superior magnetic and transport properties. A speci...

Equiatomic quaternary Heusler alloys: A material perspective for spintronic applications

Half-metallic ferromagnetic (HMF) materials show high spin polarization and are therefore interesting to researchers due to their possible applications in spintronic devices. In these materials, while one spin sub band has a finite density of states at the Fermi level, the other sub band has a gap. Because of their high Curie temperature and tunable electronic structure, HMF Heusler alloys have a special importance among the HMF materials. Full Heusler alloys with the stoichiometric composition X2YZ (where X and Y are the transition metals and Z is a sp element) have the cubic structure with four interpenetrating fcc sublattices. When each of these four fcc sublattices is occupied by different atoms, a quaternary Heusler structure with different structural symmetry is obtained. Recently, these equiatomic quaternary Heusler alloys (EQHAs) with 1:1:1:1 stoichiometry have attracted a lot of attention due to their superior magnetic and transport properties.

Equiatomic quaternary Heusler alloys: a material perspective for spintronic applications

CoRuFeX (X = Si and Ge) Heusler alloys: High TC materials for spintronic applications

Alternating cycles of isothermal magnetization and adiabatic demagnetization applied to a magnetocaloric material can drive refrigeration in very much the same manner as cycles of gas compression and expansion. The material property of interest in finding candidate magnetocaloric materials is ΔSM, their gravimetric entropy change upon application of a magnetic field under isothermal conditions. There is, however, no general method for screening materials for such an entropy change without actually performing the relevant, time- and effort-intensive magnetic measurements. Here we propose a simple computational proxy based on performing nonmagnetic and magnetic density functional theory calculations on magnetic materials. This proxy, which we term the magnetic deformation ΣM, is a measure of how much the unit cell deforms comparing with the relaxed structures with and without the inclusion of spin polarization. ΣM appears to correlate very well with experimentally measured magnetic entropy change values. Th...

/pdf/a-simple-computational-proxy-for-screening-magnetocaloric-2apw46zin6.pdf

A Simple Computational Proxy for Screening Magnetocaloric Compounds

Transition metal silicides: fundamentals, preparation and catalytic applications

Magnetic and crystallographic properties of bulk Co2Fe(Ga1−xSix) alloys with 0≤x≤1 are reported in this work. The alloys with x=0.75 and 1.00 exhibit L21 structure whereas the alloys with x=0, 0.25 and 0.50 crystallized in the disordered A2 phase. Unit cell volume of this series of alloys decreased from 189.1 to 178.5 A3 as x was increased from 0 to 1.00. All alloy compositions exhibit ferromagnetic behavior with a high Curie temperature (TC) which showed a systematic variation with x (1089 K, 1075 K, 1059 K, 1019 K and 1015 K for x=0, 0.25, 0.5, 0.75 and 1.00, respectively). The saturation magnetization moment Ms for the alloys with x=0, 0.25 and 0.50 are 5.05μB, 5.23μB, 5.49μB, respectively, in accordance with the Slater–Pauling rule, but alloys with x=0.75 and 1.00 deviated from this rule. The effective moment per magnetic atom (pc) of the alloys was estimated from the inverse DC magnetic susceptibility data above TC. A comparison of Ms with pc reveals the half-metallic character of the alloys.

Magnetic properties of Co2Fe(Ga1−xSix) alloys

Magnetic properties of Ge substituted Ru2FeSi alloys

Effect of atomic disorder on magnetization and half-metallic character of Cr2CoGa alloy

In this work, we report a systemetic study of Co substitution for Ru in Ru 2 FeSi. Our previous studies showed that Ru 2 FeSi and Co 2 FeSi are antiferromagnetic and ferromagnetic, respectively. In order to understand the influence of Co substitution for Ru, (Ru 1− x Co x ) 2 FeSi alloys were prepared by arc melting, followed by annealing at 1273 K for 3 days. Structural and magnetic studies were carried out on the quaternary alloys by powder X-ray diffraction and vibrating sample magnetometry, respectively. At room temperature, Ru rich compositions i.e., x =0 and x =0.25 exhibited disordered B2 structure, but with increase in Co concentration L2 1 ordering appeared in the alloys. From magnetization measurements, it is seen that with increasing x , the ferromagnetic state becomes dominant with the appearance of spontaneous magnetization and increase in the value of magnetization of the alloys. Saturation magnetization measured at 15 kOe increased from 1.02 emu/g to 149.96 emu/g as x was increased from 0 to 1.

Bhargab Deka

Papers

Magnetic properties of Co2Fe(Ga1−xSix) alloys

Magnetic properties of Ge substituted Ru2FeSi alloys

Effect of atomic disorder on magnetization and half-metallic character of Cr2CoGa alloy

Magnetic and structural properties of (Ru1−xCox)2FeSi alloys

Effect of electron-electron correlation and site disorder on the magnetic moment and half-metallicity of Co2FeGa1−xSix alloys