D.S. Neznakhin

The Spin-Reorientation Transition in a Nanocrystalline Nd-Ho-Fe-Co-B Alloy and its Influence on the Hysteresis Loops

The temperature dependence of coercivity (Hc) of a nanocrystalline (Nd0.55Ho0.45)2.7(Fe0.8Co0.2)14B1.2 alloy in a wide temperature range, including the spin reorientation (SR) transition interval, has been investigated. A considerable decrease in the Hc for the SR in the range 150–4.2 K was detected and interpreted as being an effect caused by the anisotropy change of the 2-14-1 phase nanograins, i.e., from the uniaxial to the easy-cone type.

Determination of the Existence Region of a Griffith-Like Phase in Pr 1– x Sr x MnO 3 /YSZ Films

We have studied the temperature dependences of the magnetic susceptibility and the electron magnetic resonance in Pr1–xSrxMnO3/YSZ polycrystalline films (x = 0.2, 0.4). The paramagnetic properties of samples indicate the presence of short-range-order ferromagnetic correlations above the phase transition temperature (Tc). The existence region of such correlations has been considered using the Griffith theory.

Pressure Induced AF - F - AF Magnetic Phase Transformations in Pd Substituted FeRh Compound

At ambient pressure, the Fe0.49(Rh1-xPdx)0.51 alloys with the Pd concentration within 0 < x < 0.12 exhibit an antiferromagnetic (AF) state below the critical temperature Tt, while above x = 0.12 the alloys have a ferromagnetic (F) order up to the Curie temperature TC 650 K. The temperature and field dependences of the magnetization in the alloys with x = 0.08; 0.13 were investigated under hydrostatic pressure up to 10 kbar. The application of pressure of about 8.5 kbar is observed to induce the F-AF phase transition in the ferromagnetically ordered compound with x = 0.13. The AF-F-AF phase evolution was revealed with increasing pressure in the AF-ordered alloy with x = 0.08.

Microstructure and Magnetic Hysteresis in Nanocrystalline Nd-Fe-Co-B Alloys on the Base of Nd2Fe14B Phase

Using the electron microscopy (SEM and TEM), X-ray structure analysis and precise magnetometry methods (VSM, SQUID-magnetometer), the microstructure and magnetic hysteresis properties of industrial manufactured hard magnetic rare-earth based alloys of Nd-Fe-Co-B compositions (BZMP and MQP-B brands) that are widely applied as fillers for bonded magnets (magnetoplasts and magnetoelasts) have been studied. The obtained results allow selecting the proper temperature range for bonded magnets applications on the base of BZMP and MQP-B fillers.

Structural, electrical and magnetic study of manganites Pr0.6Sr0.4MnO3 thin films

Thin polycrystalline Pr0.6Sr0.4MnO3 films were grown on the Y stabilized zirconium oxide substrates by magnetron sputtering using RF power and off-axis sputtering scheme with double cathodes. Only one polycrystalline phase with structural parameters consistent with that for the corresponding bulk sample was revealed in the films. Electric resistivity dependence on temperature demonstrates the shape characteristic for the substances with the Mott transition. The difference between magnetization temperature curves measured in the zero field cooling and field cooling modes was revealed. Magnetization field dependences were presented by the hysteresis loops changing their form with temperature.

Structure and magnetic properties of Nd9Fe74B12Ti4C rapidly quenched alloys prepared by melt electrospinning using centrifuge technique

The X-ray diffraction analysis and magnetometry methods were used to investigate the phase composition and magnetic properties of rapidly quenched Nd9Fe74B12Ti4C alloys. The rapidly quenched alloys were prepared by the spinning of the melt of a specified composition using a centrifuge technique with the use of electric current passing through an injected stream during quenching. The rapidly quenched alloys in the form of flakes (plane fragments of a metal ribbon) were subjected to short-term annealing in the temperature range between 550–1000°C. It was found that the alloy prepared with passage of an electric current contains a larger amount of amorphous phase than that prepared without passage of an electric current. This fact is reflected in the difference between the processes of their devitrification during short-term annealing. The anisotropy of hysteresis properties of flakes annealed at 720°C was discovered along and in the plane perpendicular to the planes of flakes (of a “fanlike” texture) during their magnetizing.