Half metallicity in Cr substituted Fe2TiSn

Electronic, magnetic, and structural properties of NiFeMnAl

Half-metallic Heusler compounds have been extensively studied in the recent years, both experimentally and theoretically, for potential applications in spin-based electronics. Here, we present the results of a combined theoretical and experimental study of the quaternary Heusler compound NiFeMnAl. Our calculations indicate that this material is half-metallic in the ground state and maintains its half-metallic electronic structure under a considerable range of external hydrostatic pressure and biaxial strain. NiFeMnAl crystallizes in the regular cubic Heusler structure, and exhibits ferromagnetic alignment. The practical feasibility of the proposed system is confirmed in the experimental section of this work. More specifically, a bulk ingot of NiFeMnAl was synthesized in A2 type disordered cubic structure using arc melting. It shows a high Curie temperature of about 468 K and a saturation magnetization of 2.3μB/f.u. The measured magnetization value is smaller than the one calculated for the ordered structure. This discrepancy is likely due to the A2 type atomic disorder, as demonstrated by our calculations. We hope that the presented results may be useful for researchers working on practical applications of spin-based electronics.

Observation of Griffiths-like phase in the quaternary Heusler compound NiFeTiSn

The quaternary Heusler compound NiFeTiSn can be considered to be derived from the exotic pseudogap-compound Fe₂TiSn by the replacement of one Fe atom by Ni. In contrast to Fe₂TiSn, which shows a disorder induced ferromagnetic phase, the ground state of NiFeTiSn is antiferromagnetic with the signature of spin canting. Interestingly, NiFeTiSn shows a Griffiths-like phase characterized by isolated ferromagnetic clusters before attaining the antiferromagnetic state. The Griffiths-like phase is possibly associated with the antisite disorder between Fe and Ti sites as evident from our powder x-ray diffraction study. The compound also shows rather unusual temperature dependence of resistivity, which can be accounted by the prevailing structural disorder in the system. NiFeTiSn turned out to be a rare example where Griffiths-like phase is observed in a semiconducting 3dtransition metal based intermetallic compound with antiferromagnetic ground state.

Large-scale synthesis of mixed valence K3[Fe2S4] with high dielectric and ferrimagnetic characteristics

Large scale, high purity synthesis of K3[Fe2S4] which indicates soft ferrimagnetic, high dielectric and semiconductive characteristics.

Transport properties of Heusler compounds and alloys

Heusler compounds are a large group of intermetallic compositions with versatile material properties. In recent times, they are found to be important for their practical applications in the fields of spintronics and shape memory effect. Interestingly, their physical properties can be easily tuned by varying the valence electron concentration through proper doping and substitution. Empirical laws concerning the valence electron concentration, such as Slater-Pauling or Hume-Rothery rules are found to be useful in predicting their electronic, magnetic and structural properties quite accurately. Electrical transport measurements are simple laboratory-based techniques to gather a handful of information on the electronic properties of metals and semiconductors. The present review aimed to provide a comprehensive view of the transport in 3dand 4dtransition metal-based bulk Heusler compositions. The main emphasis is given on resistivity, magnetoresistance, Hall effect, thermopower and spin-dependent transport in spintronics devices. The review primarily focuses on magnetic Heusler compounds and alloys, albeit it also addresses several non-magnetic materials showing superconductivity or large thermopower.