CoFeMnSi has been both experimentally and theoretically proven as a novel spin-gapless semiconductor and resulted in a new research direction in equiatomic full Heusler compounds. Using the first-principles calculation method, we investigated the electronic, magnetic and mechanical properties of CoFeMnSi material in this study. The obtained lattice constant under the LiMgPdSn-type Heusler structure is 5.611 Å and it is fairly consistent with previous experimental results and theoretical calculations. Furthermore, the achieved total magnetic moment of 4 μ_B follows the Slater–Pauling rule as M_total = Z_total − 24, where M_total is the total magnetic moment per formula unit and Z_total is the total valence electron number, i.e., 28 for CoFeMnSi material. We have also examined the mechanical properties of CoFeMnSi and computed its elastic constants and various moduli. Results show CoFeMnSi behaves in a ductile fashion and its strong elastic anisotropy is revealed with the help of the 3D-directional-dependent Young’s and shear moduli. Both mechanical and dynamic stabilities of CoFeMnSi are verified. In addition, strain effects on the electronic and magnetic properties of CoFeMnSi have been investigated, including both uniform and tetragonal strains, and we found that the spin-gapless feature is easily destroyed with both strain conditions, yet the total magnetic moment maintains a good stability. Furthermore, the specific behaviors under various temperatures and pressures have been accessed by the thermodynamic properties with a quasi-harmonic Debye model, including bulk modulus, thermal expansion coefficient, Grüneisen constant, heat capacity and Debye temperature. This comprehensive study can offer a very helpful and valuable reference for other relative research works.

A series of ferromagnetic Ni80Fe20(55 nm)/antiferromagnetic CoO (25 to 200 nm)/ferromagnetic Co (55 nm)/SiO2(substrate) trilayer thin films were fabricated by ion-beam assisted deposition in order to understand the role of ion beam modification on the interfacial and interlayer coupling. The microstructural study using transmission electron microscopy, X-ray reflectometry, and polarised neutron reflectometry showed that ion-beam modification during the deposition process led to an oxygen-rich Co/CoO nanocomposite interface region at the bottom layer. This interface caused a high exchange bias field for the ferromagnetic cobalt. However, the exchange bias for top permalloy ferromagnet remained low, in line with expectations from the literature for the typical interfacial energy. This suggest that the ion-beam enhancement of the magnetic exchange bias is localized to the Co/CoO interface where local microstructural effects provide the dominant mechanism.

The equiatomic quaternary Heusler compound TiZnMnSi exhibits strong tendency to tetragonal phase transformation.

The electronic, magnetic and mechanical properties of the quaternary compound Cu₂FeSnS₄ have been investigated with first principle calculations. Its half-metallicity has been identified with spin polarized band structures and its magnetic origination is caused by the strong spin splitting effect in the d orbitals of Fe atoms. The total magnetic moment of 4 μ_B is mainly contributed by the Fe atoms and the spatial distribution of the magnetic spin density and charge density difference have also been examined. Moreover, several mechanical properties of Cu₂FeSnS₄ have been derived and its mechanical stability is also verified. The directional dependent Young’s modulus exhibits relatively small anisotropy yet the shear modulus shows strong directional anisotropy. At last, the tetragonal strain effects have been evaluated and their impact on the electronic and magnetic properties are provided. Results show the total magnetic moment stays almost unchanged while the half-metallicity can only be maintained under relatively small variations for both strains. This study can provide comprehensive information about the various properties of Cu₂FeSnS₄ compound and serve as a helpful reference for its future applications.