Abstract: Direct measurements of the magnetocaloric effect (MCE) in RCo5 single crystals in the region of spin-reorientation transitions (SRT) were carried out. It was shown that the values of MCE in the region of SRTs are comparable to the values of MCE in the vicinity of the Curie temperature. The anisotropy constants of the compounds were measured by the torque method. The anisotropic MCE calculation on the basis of anisotropy constants showed a good accordance with the experimental data.
Abstract: The Tm2Fe17 compound has been studied by means of powder neutron diffraction. The compound undergoes a spin-reorientation transition (SRT) of the “easy axis – easy plane” type with increasing temperature from 75 K to 100 K. The SRT is accompanied by a distinct anomaly in the temperature dependencies of the Tm- and Fe-ion magnetizations, significative of large magnetization anisotropy. Using three sublattices model, the parameter of the Tm-Fe interaction and constants of magnetic anisotropy are determined.
Abstract: The results of experimental research into magnetic properties of amorphous Co-P films obtained by chemical sedimentation on various intermediate layers have been represented. The nuclear magnetic resonance (NMR) spectra of films sedimentated on intermediate layers of Pd crystal and amorphous NiP compound have been measured .The features of formation of domain structures and magnetization processes in the presence and absence of the induced anisotropy have been described.
Abstract: Magnetic properties of Ni3Al1-yMny alloys at y≤0.6 were investigated at T≤400 K in magnetic fields H≤4 MA/m. The concentration y dependencies of the spontaneous magnetic moment s, the effective magnetic moment eff, the Curie temperature ТС, the Weiss constant , and the temperature independent part of the magnetic susceptibility 0 were determined. The behavior of the Rhodes-Wohlfarth parameter р(y) in the transition region from the itinerant electron magnetism to the spin localized one is related to the increase in the spontaneous magnetic moment of Ni atoms inversely proportional to the average distance between Mn atoms with the highly localized magnetic moments.
Abstract: Spontaneous magnetization Ms of the ferromagnetic compound Mn5Ge3 with the Curie temperature TC=305 K has been studied in the temperature range from 2 to 400 K. The relationships between the magnetic part of the heat capacity (CMAG), the magnetic part of the volume thermal expansion coefficient (TEC) MAG, and the Ms for the compound Mn5Ge3 have been considered. It has been found that the magnetic part of the heat capacity can be well approximated by the dependence CMAG(T)=a×|dMs2/dT|–b×|dMs4/dT| with a>0 and b>0, and the magnetic part of the TEC, by the dependence MAG=C1×dMs2/dT+C2×dMs4/dT with C1<0 and C2>0 in the whole temperature. It is assumed that the main sources in the formation of the observed CMAG(T) and MAG(T) dependences are the changes in the elastic, magnetoelastic, magnetovolume, and magnetostatic energies of the sample that appear as a result of the spontaneous magnetostrictive deformation with temperature changing.
Abstract: The intercalated compound Fe0.5TiSe2 has been studied by means of X-ray, neutron diffraction, electrical resistivity and magnetization measurements. This compound with Fe atoms located between Se-Ti-Se sandwiches has a monoclinic crystal structure and exhibits a long-range antiferromagnetic (AF) ordering below TN = 135 K. At T < TN, the Fe magnetic moments with a value ~ 3.0 µB are directed at an angle of (74.4±0.5)º to the layers and form a tilted antiferromagnetic structure with the propagation vector (½, 0, ½). It has been shown that application of magnetic field above 300 kOe may lead to transformations of the AF structure.
Abstract: Six samples of Nd-Fe-B-permanent magnets, distinguished in the texture degree, have been measured by neutron diffraction in the reflection and transmission regimes. The texture in the samples was formed by application of impulses of external magnetic field 0H = 4 T. Analysis of the obtained neutron diagrams by means of the Fullprof program allowed quantitative determination of the texture degree and conclusion to be made that the texture degree grows with an increase in numbers of magnetic field impulses.
Abstract: The magnetocaloric effect (MCE) in theNi2+xMn1-xGa (x = 0.33, 0.36, 0.39), Ni50Mn25In25, Ni54Mn21Ga18In7, Ni53.5Mn21.5Ga16In9, Ni45Co5Mn36.5In13.5 Heusler alloys and in the La0.7BayCa0.3-yMnO3 (y = 0.12, 0.24, 0.3) manganites at the Curie points have been measured by the direct method. For the magnetic field change H = 2 T, the maximal adiabatic temperature change Tad in the Ni2+xMn1-xGa alloys is larger than 0.6 K. For the Ni50Mn25In25 alloy the maximal value of Tad = 1.51 K (for the same magnetic field change H = 2 T) is observed at the magnetic phase transition temperature.
Abstract: The results of magnetic behavior study of nickel ions, which were introduced into Zn2Fe(CN)6∙5.5H2O with channel structure, are presented. It was shown that nickel cations replace a part of Zn2+ ions or locate in the channels of lattice via the molecular mechanism sorption. It is shown that the magnetic moments μNi of the sorption products strongly depend on the content of Ni2+ ions. The values of μNi of the samples with Ni/Fe(CN)6=2.26 and 2.86 are great ~ 3.9 and 4.4 μB respectively and close to the value typical of free Ni2+ ions μ =4.47μB.
Abstract: In a trigonal easy-plane -Fe2O3 antiferromagnet magnetic-field-dependent conic refraction due to the renormalization of the coefficients of elasticity effective magnetoelastic interaction is experimentally found in addition to the conventional internal conic refraction of the transverse elastic waves propagating along the trigonal C3 axis. It is shown that the deflection angle () of the energy flow from the C3 axis upon the internal conic refraction does not depend on the value of the magnetic field applied in the basis plane (HC3) and is a constant value determined by the correlation of the C14 and C44 coefficients of elasticity. The deflection angle of the energy flow upon the antiferromagnetic conic refraction () increases with increase in the field and tends to the value at large H values. The obtained results agree well with the theory of this phenomenon in antiferromagnets and support its conclusions.