The magneto-transport properties are investigated in metamagnetic CoMnSi 0.88 Ge 0.12 alloy. By applying a magnetic field or increasing temperature, a metamagnetic phase transition from antiferromagnetic to ferromagnetic is observed in this alloy. Around the metamagnetic phase transition, CoMnSi 0.88 Ge 0.12 alloy exhibits a large and negative magnetoresistance effect (∼32%) under a magnetic field of 20 kOe (1 Oe = 79.5775 A/m), which is ascribed to the spin-dependent scattering of conduction electrons.

Spinel ferrites, such as CoFe2O4, can be used in various fields such as computer technology, aerospace, and medical biotechnology due to their good electromagnetic properties. Although, CoFe2O4 thin films have good application prospects in the magnetoelectric composites, the effects of strain on the electronic structure and magnetic properties of cobalt ferrite film have not been reported. Through the use of two-dimensional strain model closer to the epitaxial growth experiments, the films of Cobalt ferrite are simulated on various substrates with a realistic biaxial strain model by first-principles plane-wave pseudopotential method based on density functional theory, and combined with the generalized gradient approximation in the paper. And the structural stabilities, electronic structures and magnetic properties of CoFe2O4 films are studied. The results show that the inverse spinel is still energetically favored under strain, but the energy difference decreases, thus Fe3+ions in the tetrahedral sites and Co2+ ions in the octahedral sites are easier to exchange their positions. As the strain increases, the band gap of cobalt ferrite becomes narrower, and the magnetic moment of atom in the lattice changes, while the net magnetic moment changes little.

The spontaneous magnetization of the Ho3+ ion in holmium iron garnet (HoIG) single crystals in the temperature range of 4.2-294 K along the directions [111], [110], and [100] are calculated, taking into account the effects of six magnetically inequivalent sites occupied by the Ho3+ ions based on the quantum theory. The calculated results show that the magnetization of the Ho3+ ion in HoIG is obviously anisotropic. The theoretical results are in agreement with those of experiments. A primary interpretation of the anisotropy of magnetization of the Ho3+ ion in HoIG is put forward.