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The magnetic properties of ceramic La1−xSrxMn1−yFeyO3 samples with x = 0.3 and y = 0.15−0.25 are investigated in magnetic fields of B = 10−103 G at a temperature T between 5−310 K. A ferromagnetic transition at TC, decreasing considerably with y, is accompanied with strong magnetic irreversibility at B = 10 G. The critical behavior of χ (T) ~ (T/TC − 1)−γ is governed at y = 0.15−0.20 by the percolative (γ ≈ 1.8) and Heisenberg (γ ≈ 1.4) spin systems.

The article is concerned with the analysis of magnetic impurity influence on the prop- erties of As2S3 and As2Se3 chalcogenide glasses. Measurements of magnetic susceptibility were performed in the 1-350 K temperature range and in the permanent magnetic fields up to 5 T. Amphoteric elements Mn and Cr, as well as rare-earth element Yb, were chosen as doping elements. Experimental data reveal different dependences of specific magnetic moment on temperature M = M(T) in the strong magnetic fields to 5 T and have some specific features which depend on dopant material and on composition of diamagnetic chalcogenide glass.

Magnetic and galvanomagnetic properties of the group II-V semiconductor CdSb single crystals doped with Ni are reported. The magnetization data give evidence for spheroidal Ni- rich Ni1-xSbx nanoclusters. Mechanism of the low-temperature conductivity is sensitive to the magnetic field, being of the variable-range hopping type in zero field and of the nearest- neighbor hopping type in strong fields. The Hall resistivity contains the normal and the anomalous contributions.

Magnetic properties of the group II-V semiconductor CdSb single crystals doped with Ni (2 at %) are investigated. The magnetic irreversibility in low (B

We present results of experimental studies of magnetic properties, resistivity and magnetoresistance (MR) of (Co84Nb14Ta2)x(Al2O3)100-x films deposited onto a glass-ceramic substrate by the ion-beam sputtering, focusing on MR in high magnetic fields for compositions close to the percolation threshold (x=47-57 at.%). The samples consist on Co-Nb-Ta metallic nanogranules size of 2-5 nm which are embedded into the non-stoichiometric Al-O matrix. Magnetization was measured by SQUID magnetometer at T=4.2-350 K. MR was studied in the pulsed magnetic fields μ0H up to 20 T at T=70-300 K in three geometries: magnetic field in plane parallel and perpendicular to current, magnetic field perpendicular to plane. The pulse duration was 11-12 ms. For the sample with x=57 at.% the temperature dependence of conductivity follows the lnT behavior that matches a strong tunnel coupling between nanogranules. With decreasing metal volume fraction lnT behavior gradually changes to the T1/2 dependence at 47 at.%. For all samples MR is small (

Fe73.9Cu1Nb3Si13.2B8.9 (Finemet) thin films were deposited on the glass substrates by means of radio frequency sputtering. The films thickness was varied from 10 to 200 nm. Heat treatment at temperatures of 350, 400 and 450 °C were performed for 30 minutes in order to control thin film structural state. The X-ray powder diffractometry revealed that the crystallization of α-FeSi nanograins took place only at 450 °C whilst the other samples stayed in the amorphous state. Relation between the structure and magnetic properties of the films was discussed in the framework of random magnetic anisotropy model and the concept of stochastic magnetic domains. The latter was investigated using magnetic force microscopy (MFM). MFM data showed formation of such magnetic domains only in samples thermally treated at 450 °C. There was a tendency of the magnetic domain size reduction with the thickness decrease.

Single crystals of a diluted magnetic semiconductor (Cd1-x-yZnxMny)3As2 (CZMA) (x + y = 0.4;y=0.04 and 0.08) obtained by Bridgman method were used. The Shubnikov-de Haas (SdH) effect was observed within studying of the dependence of the resistivity on the magnetic field in CZMA solid solutions. The values of the cyclotron mass mc, Hall and Shubnikov carrier concentrations were calculated.

Magnetostructural transition was observed in Ni-Mn-In-Cr Heusler alloy with help of Magnetic Force Microscopy (MFM). The crystal structure of a sample and characteristic temperatures of the phase transition were controlled by roentgenostructural phase analysis and magnetometry, respectively. It appeared prominently important to prepare the surface of the sample until the nanometer level of surface roughness. Magnetic study performed with scanning probe microscope revealed existence of magnetic domains, which were spread across the surface evenly. Further studies revealed that intensity of magnetic signal decreases as fading out of the contrast of the MFM images. It was found that location of domains shifted after the heating/cooling cycle above Curie temperature for the studied alloy. Location of new domain walls appeared correlating with surface scrapings and defects, whilst it became independent from those after heating until just 70°C. The mechanism behind the observed transition is proposed.

In this work, magnetic properties of activated carbon coal, which is also named amorphous carbon, were investigated. Composition and structure analysis was performed by XRD, SEM and EDS techniques. Position and width of peaks on XRD pattern confirmed amorphous structure of coals with small degree of graphitization. Magnetic measurements were performed by SQUID magnetometer. According to thermomagnetic measurements, in part of the samples, antiferromagnetic transition was observed near 120 K. Nature of such phenomena, as well as effect of oxygen and magnetic contaminations on thermomagnetic measurements are discussed referring to similar results from previous researches and data from literature.