Structural, electronic and magnetic properties of quaternary half‐metallic Heusler alloy CoFeCrAl

Abstract

We have investigated the structural, electronic and magnetic properties in quaternary CoFeCrAl Heusler alloy. Rietveld refinement and Mössbauer spectroscopy of samples quenched from 973 K show absence of the A2 phase and presence of a highly ordered B2‐type structure. Full‐potential linearized augmented plane wave calculations using the experimental lattice constant show that there is an energy gap of 0.41 eV around the Fermi level in the bands for minority spin electrons. Partial substitution of Co by Fe in Co2CrAl thus brings excellent structural ordering while retaining the high Curie temperature, spontaneous magnetization and half‐metallicity necessary for application as spin valves. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Equiatomic quaternary Heusler alloys: A material perspective for spintronic applications

“…The XRD results of Bainsla et al are found to be in good agreement with the reports by Luo et al [47] and Nehra et al [48].…”

“…Curie temperature of 460 K for the alloy was obtained using the thermomagnetic curves recorded by them. Nehra et al [48] also studied the magnetic properties of the as-melted as well as quenched CoFeCrAl alloy and found a bifurcation between the zero field cooled and field 13 cooled thermomagnetic data. They also observed that the difference between these two data decreases with increase in the cooling field and entirely disappears in a cooling field of ~1.5…”

“…These authors attributed the magnetic behavior to the antiferromagnetic interactions between Cr-Co/Fe and Cr at ordinary sites with Cr at the anti (Al) sites. The TC values of 410 and 515 K were obtained for as-melted and quenched CoFeCrAl samples respectively [48].…”

Effect of partial substitution of silicon by other sp-valent elements on structure, magnetic properties and electrical resistivity of Co2FeSi Heusler alloys

“…Theoretical calculations have shown that anti-site disorder destroys the high spin polarization [12] by disturbing the Fermi surface at the top of spin-down sub-band. Attempts have been made to adjust the position of the Fermi level in various Heusler alloys by partial substitution of transition metal occupying the Y site by another transition metal for example Co 2 Mn 1Àx Fe x Si [13] and Co 2 Cr 1Àx Fe x Al [14]. However, the theoretically predicted values of spin polarization values were not achieved.…”

Structural and magnetic properties of a new and ordered quaternary alloy MnNiCuSb (SG: F4¯3m)

“…In such Heusler alloys, one of the X atoms is completely substituted by another transition metal element. There are only few examples known for such quaternary alloys, CoFeMnZ (Z ¼Al, Ga, Si and Ge) [20,21], CoFeCrAl [22], CoFeMnSi [23] NiCoMnZ (Z ¼Al, Ge and Sn) [24] NiFeMnGa, NiCoMnGa and CuCoMnGa [25] CoFe 1 þ x Ti 1 À x Al and CoMn 1 þ x V 1 À x Al [26,27]. Ordered quaternary Heusler alloys are formed when the occupancy of each atom at the four Wyckoff positions is unity.…”