Correlation between the synthesis conditions and the compositional and magnetic properties of Co2(Cr1−xFex)Al Heusler alloys

Effect of annealing on spinodally decomposed Co2CrAl grown via floating zone technique

“…Arc-melted samples of Co 2 CrAl are phase segregated, similar to an earlier work [6], as seen by the strong contrast in the backscattered electron (BSE) image (Fig.3a) although the two phases have similar structure and are thus indistinguishable in XRD. Recently, crystal growth using optical floating zone (FZ) technique was undertaken for the Co 2 CrAl compound in an attempt to grow single-phase sample as the FZ technique provides the possibility to grow incongruently melting systems.…”

“…At 750 °C, we are well within the two-phase regime as we see a pronounced secondary phase in sample annealed at that temperature. It goes on to show the high stability of the σ phase and the tetragonal phase is even seen for annealed polycrystalline samples [6]. Thus, dissolving the secondary σ-CoCr phase via annealing, at least till 1250 °C, can be excluded as a possible way to obtain a single phase sample.…”

“…Hence, Co 2 CrAl is also expected to show high magnetoresistance effect. Anomalous data have been reported in the past, both in bulk materials [6][7][8][9] as well as in films [10,11]. The anomalies may be attributed to chemical phase separation found in various samples [12][13][14][15][16].…”

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

“…The experimental values of saturation magnetic moment ( M S ) and spin polarization for the Co 2 CrAl alloy (1.55 μ B / formula unit (f.u.) and 62% half‐metallicity) are thus significantly lower than the values predicted by calculations 4–7. If the formation of the A2 phase can be avoided so that at least B2 ordering is realized, the predicted 100% spin polarization can be achieved since it has been shown 8, 9 that the spin polarization is not affected by this type of preferential disorder.…”

Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

“…The appearance of (111) and (200) reflections indicates that there is no structural disorder in NiCoMnSn. [28] However, for NiCoMnGe and NiCoMnAl, mere absence of (111) and (200) reflections in XRD patterns cannot be taken as the evidence of the disordered state. This is because the nearly equal scattering amplitudes of all the constituent elements (3d and 4p) do not allow a detailed order-disorder analysis by using XRD [28].…”