Magnetic States and Electronic Properties of Manganese-Based Intermetallic Compounds MnAl and Mn ( = V, Cr, Fe, Co, Ni; = Al, Ge, Sn, Si, Pt).

We present a brief review of experimental and theoretical papers on studies of electron transport and magnetic properties in manganese-based compounds Mn and Mn ( = V, Cr, Fe, Co, Ni, etc.; = Al, Ge, Sn, Si, Pt, etc.).

Incommensurate magnetic order in rare earth and transition metal compounds with local moments.

Within the framework of the-() exchange model in the mean-field approximation for square, simple cubic, body-centered and face-centered cubic lattices, the formation of a ferromagnetic, spiral, and commensurate antiferromagnetic (AFM) order is investigated. The possibility of the formation of inhomogeneous states (magnetic phase separation), which necessarily arises during first-order phase transitions in the electron filling parameter, is taken into account. The saturation of the AFM and spiral states is studied depending on the parameters of the model.

Scaling theory of magnetism in frustrated Kondo lattices.

A scaling theory of the Kondo lattices with frustrated exchange interactions is developed, criterium of antiferromagnetic ordering and quantum-disordered state being investigated. The calculations taking into account magnon and incoherent spin dynamics are performed. Depending on the bare model parameters, one or two quantum phase transitions into non-magnetic spin-liquid and Kondo Fermi-liquid ground states can occur with increasing the bare coupling constant.

Spiral magnetism in the single-band Hubbard model: the Hartree-Fock and slave-boson approaches.

The ground-state magnetic phase diagram is investigated within the single-band Hubbard model for square and different cubic lattices. The results of employing the generalized non-correlated mean-field (Hartree-Fock) approximation and generalized slave-boson approach by Kotliar and Ruckenstein with correlation effects included are compared. We take into account commensurate ferromagnetic, antiferromagnetic, and incommensurate (spiral) magnetic phases, as well as phase separation into magnetic phases of different types, which was often lacking in previous investigations.

Non-quasiparticle states in a half-metallic ferromagnet with antiferromagnetic s-d(f) interaction.

Non-quasiparticle (incoherent) states which play an important role in the electronic structure of half-metallic ferromagnets (HMF) are investigated consistently in the case of antiferromagnetic s-d(f) exchange interaction. Their appropriate description in the limit of strong correlations requires a rearrangement of perturbation series in comparison with the usual Dyson equation. This consideration provides a solution of the Kondo problem in the HMF case and can be important for first-principle HMF calculations performed earlier for ferromagnetic s-d(f) interaction.