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The spin-1/2 Ising diamond chain in a magnetic field displays a remarkable pseudo-transition whenever it is driven sufficiently close to a ground-state phase boundary between a classical ferrimagnetic phase and a highly degenerate frustrated phase. The pseudo-transition of the spin-1/2 Ising diamond chain relates to intense thermal excitations from a nondegenerate ferrimagnetic ground state to a highly degenerate manifold of excited states with a frustrated character, which are responsible for an anomalous behavior of thermodynamic quantities. Temperature dependences of entropy and specific heat are indeed reminiscent of a temperature-driven phase transition of a discontinuous (entropy) or continuous (specific heat) nature though there are no true singularities of these thermodynamic quantities at a pseudo-critical temperature. [ABSTRACT FROM AUTHOR]

We consider the effect of the Rashba spin-orbital coupling in two-dimensional GaAs semiconductor heavily doped with Mn, on the spin polarization of holes. Due to the strong internal spin-orbit interaction in GaAs, the spin of a hole is not a good quantum number but the hole in some energy state has a certain mean value of spin, which can be strongly affected by the Rashba spin-orbital interaction related to the substrate for 2D material. [ABSTRACT FROM AUTHOR]

Mixed-metal complex consisting of ruthenium(II,III) pivalate, ([Ru2(piv)4]+) (Hpiv = pivalic acid), tetraethylammonium and octacyanidotungstate(V) ions, (Et4N)[{Ru2(piv)4g2W(CN)8] · 4H2O, was synthesized and characterized by elemental analysis, infrared and UV-vis spectra and temperature dependence of magnetic susceptibilities (2-300 K). The magnetic susceptibilities, zero-field-cooled and field-cooled magnetizations, and AC susceptibility data showed that the present complex is ferrimagnetic with Tc value of 80 K. The field dependence of magnetization exhibited a hysteresis with a coercive field of 17000 Oe at 5 K. [ABSTRACT FROM AUTHOR]

Structural design of barium hexaferrites BaMgxCo2-xFe16O27 (x = 0:0, 1, 2) has been studied, and the magnetic and electronic structure of that has then been investigated using first principle total energy calculation. All calculations are based on the density functional theory. In order to improve the description of strongly correlated 3d electrons of iron, the general gradient approximation plus Hubbard U (GGA+U) method is used. We found that in the lowest energy configuration Mg and Co ions preferentially occupy the 6g sites. With the increase of Mg content x, the energy gap of BaMgxCo2-xFe16O27 increases but the lattice constant of unit cell decreases. The magnetic moment of the unit cell for Mg content x = 0, 1, and 2 are calculated to be 52, 49 and 46 μB/cell, respectively, in agreement with previous experimental results. The substitutions of Mg and Co at the BaFe2+2 Fe3+16O27 decrease electrical conductivity and transit it from a half-metal to semiconductor material. Based on our calculations on electronic band structure, the BaFe2Fe16O27 (BFFO) is a weak half-metal, but BaMg2Fe16O27 (BMFO), BaMgCoFe16O27 (BMCFO) and BaCo2Fe16O27 (BCFO) are semiconductors. The electrical resistivity increases by increasing Mg and Co contents due to increase in porosity which prevents the hopping of charge carriers. [ABSTRACT FROM AUTHOR]

Magnetization curves of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are calculated with the help of density-matrix renormalization group method for several quantum spin numbers S=1, 3/2, 2 and 5/2. It is shown that the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains exhibit irrespective of the spin value S exactly one intermediate magnetization plateau, which can be identified with the gapped Lieb-Mattis ferrimagnetic ground state. The magnetization plateau due to the Lieb-Mattis ferrimagnetism breaks down at a quantum phase transition towards the Luttinger spin liquid, which is characterized by a continuous change of the magnetization with the magnetic field until another quantum critical point is reached at the saturation field. [ABSTRACT FROM AUTHOR]

The effect of uniaxial single-ion anisotropy on magnetic and critical properties of the mixed spin-1/2 and spin- S (S > 1=2) Ising model on a three-coordinated Bethe lattice is rigorously examined with the help of star-triangle transformation and exact recursion relations. In particular, our attention is focused on the ferrimagnetic version of the model, which exhibits diverse temperature dependences of the total and both sublattice magnetizations. It is shown that the critical behavior of the mixed-spin Ising model on the Bethe lattice basically depends on whether the quantum spin number S is integer or half-odd-integer. [ABSTRACT FROM AUTHOR]

The effect of the canting of local anisotropy axes on the ground-state phase diagram and magnetization of a ferrimagnetic chain with regularly alternating Ising and Heisenberg spins is exactly examined in an arbitrarily oriented magnetic field. It is shown that individual contributions of the Ising and Heisenberg spins to the total magnetization basically depend on the spatial orientation of the magnetic field and the canting angle between two different local anisotropy axes of the Ising spins. [ABSTRACT FROM AUTHOR]

CuCr2Te4 can be obtain by mechanical alloying followed by heat treatment. The obtained phase crystallizes in the spinel-type structure of the space group Fd3m. The calculated crystallite size equals to 100 nm. Magnetic susceptibility measurements showed ferrimagnetic order below 21 K. [ABSTRACT FROM AUTHOR]

Hyperfine magnetic fields on 57Fe nuclei in Sr and Ba hexagonal ferrites are calculated in dependence on unit cell volume and c/a ratio. By analysing the local deformations of Fe-O-Fe triads the results are explained as changes to contact hyperfine field due to Fe-O covalency effects and supertransferred hyperfine fields. Most pronounced effect is found for bipyramidal iron Fe(b) where the total contact field is reduced due to noticeable shortening of Fe(b)-O bonds. [ABSTRACT FROM AUTHOR]

In the present work we have shown the effciency of complex investigation of the ion implanted garnet surface region by magneto-optical and optical methods. We have investigated the optical and magneto-optical properties of the ion-implanted (YBiCaSm)3(FeGeSi)5O12 garnet films. It has shown that ion implantation influences significantly the magneto-optical properties of the garnet films and practically does not change its optical characteristics. We have also determined the spectral dependences of the component of the tensor of dielectric permittivity for the surface of ion implanted (YBiCaSm)3(FeGeSi)5O12 ferrite-garnet films before and after implantation process. These calculations let us evaluate the influence of implantation on an electronic energy structure of the surface layer for the sample. [ABSTRACT FROM AUTHOR]

The magnetization processes can be effectively studied using magnetization-induced second-harmonic generation effect (MSHG). The aim of the current work is the investigation of inhomogeneous magnetization distributions induced in the surface area of the garnet film by ion implantation. The studies were performed on magnetic garnet film of (111) symmetry, implanted with H+ 2 ions of 1.5 × 1016 cm-2 dose and 60 keV energy. The measurements of MSHG effect were performed as a function of the sample rotation angle and the amplitude of external magnetic field. The observed MSHG intensity hystereses were subjected to a decomposition procedure into contributions having different magnetic field dependences. The contributions originating from the implanted and unimplanted parts of the film volume of different magnetic ordering were analyzed and discussed. [ABSTRACT FROM AUTHOR]

The main parameters of micromagnetic structure formation in a vicinity of a second order phase transition were determined experimentally and theoretically. The theoretical study was performed using micromagnetic approach. External magnetic field Hc of appearance of micromagnetic structure and micromagnetic structure period Lc were determined for (OOl)-oriented plate with uniaxial Ku and cubic K1 magnetic anisotropy. The plate was saturated by the field applied in its plane. In the model we assumed that magnetization vector undergoes small deviations from equilibrium if magnetic field is slightly reduced. These deviations are periodic in nature: micromagnetic structure has a form of a plane wave. Dependences of Hc and Lc on an azimuthal angle of external magnetic field and on anisotropy constants Ku and K1 were derived analytically in this work. Experimental studies of micromagnetic structure near the second order phase transition were conducted on (EuEr)3(FeGa)5O12 (001)-oriented 50 μm thick ferrite-garnet plate with Ku = 5700 erg/cm3 and K1 = -3700 erg/cm3. Micromagnetic structure was revealed by means of magnetooptic Faraday effect. The in-plane field was increased up to 2000 Oe. Experimentally determined values of Hc and Lc were compared with theoretical estimates. [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical study of magnetic domain structure drift in low frequency oscillating magnetic field oriented perpendicular to the sample plate are presented. Experimental study was performed on uniaxial iron garnet (TbErGd)3(FeAl)5O12 (111) plate with rhombic anisotropy for the case when orientation of domain walls of stripe domains is preserved. Dynamic domain structure was revealed by means of magnetooptic Faraday effect, and registered by high speed digital camera at. the speed equal to 1200 fps. Theoretical model based on the motion equations for coupled harmonic oscillators that takes into account, attenuation and field inliomo-geneity along the plate is proposed. [ABSTRACT FROM AUTHOR]

The Green function theory is used to study the phenomenon of magnetic reorientation in the ferrimagnetic system. The two-sublattice ferrimagnetic system, with different spins and the intra-sublattice ferromagnetic exchange interactions, is considered. The magnon fluctuations supress in different way the magnetic orders of the sublattices and one obtains two magnetic orders. Each of these orders has different reorientation temperatures. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties (such as e.g. size of crystallites, lattice parameter, magnetic susceptibility, Curie temperature, etc.) of nano-sized Ni0.33Zn0.67Fe2O4 ferrites have been studied. The obtained results demonstrated that the sintering temperature is an efficient and simple tool for controlling the size of crystallite particles, thus affecting the resulting magnetic properties. Straightforward relationship between the sintering temperature and the size of crystallites was found, meanwhile no other crystalline phases than the spinel one were detected by two independent analytic methods. [ABSTRACT FROM AUTHOR]

The Green function theory is used to study the phenomenon of magnetic reorientation in the ferrimagnetic system. The two-sublattice ferrimagnetic system, with different spins and the intra-sublattice ferromagnetic exchange interactions, is considered. The magnon fluctuations supress in different way the magnetic orders of the sublattices and one obtains two magnetic orders. Each of these orders has different reorientation temperatures. [ABSTRACT FROM AUTHOR]