arXiv subjects

N. S. Perov

Publications and source records attributed to N. S. Perov.

7 recordsLinked to original sources

arXiv2026

Non-isothermal flow of Al-, Co- and Cu-based alloys made in different spatial configurations or structural states: model and experimental study

The universal generalising approach for non-isothermal behaviour of different alloys has been provided together with the novel deformation modelling. Strong correlation between the model approach and experimental results is shown that permits estimation of main applied parameters such as the linear thermal expansion coefficient and others. Necking contours and critical thickness at corrugation for ribbon and rod specimens are also calculated. Fractal analysis of corrugation folds (their main size) has been carried out for polycrystalline and amorphous ribbon specimens. Structural peculiarities at the plastic deformation stage are investigated with microscopy.

cond-mat.mtrl-sci↗

arXiv2025

Novel exact solutions of the Duffing equation: stability analysis and application to real non-linear deformation tests

In this study, novel exact solutions of the Duffing equation with their phase portraits have been proposed and reasoned. It is shown that phase trajectories are initially elliptical and become distorted in the unstable area within the growth of the variable parameter. Instability criteria of identified solutions have been determined together with the Fourier series transformation up to the first and high harmonics in a sense of the physical interpretation. An explicit form for the differential operator, corresponding to considered functions, has been derived with evaluation of its main functional spectrum. Non-isothermal creep tests of different materials were completely described using the Duffing equation via noted solutions up to the fracture as processes with personal deformation response. We successfully examined a relationship between the thermal and magnetic properties of the ferromagnetic amorphous alloy under its non-linear deformation, using the critical exponents. With a high linear correlation between our model and experiments, behaviour of organic and metallic systems is well predicted at the same thermo-mechanical testing conditions on the mesoscale.

cond-mat.dis-nn↗

arXiv2017

Evidence for field induced proximity type behavior in ferromagnetic nanofluid

We report some unusual magnetic properties observed in CoFe2O4 based ferrofluid (with an average particle size of D = 6 nm). More precisely, in addition to the low-field ferromagnetic (FM) phase transition with an intrinsic Curie temperature T_Cb=350K, a second phase transition with an extrinsic Curie temperature T_Cw = 266K emerges at higher (saturating) magnetic field. The transitions meet at the crossover point T_cr = 210 K. The origin of the second transition is attributed to magnetic field induced proximity type interaction between FM particles through non-FM layers.

cond-mat.mtrl-sci↗

arXiv2016

Tunneling anomalous Hall effect in the nanogranular CoFe-B-Al-O films near the metal-insulator transition

We present results of experimental studies of structural, magneto-transport and magnetic properties of CoFe-B-Al-O films deposited onto a glass ceramic substrate by the ion-beam sputtering of the target composed of Co40Fe40B20 and Al2O3 plates. The system consists on the strained crystalline CoFe metallic nanogranules with the size 2-5 nm which are embedded into the B-Al-O oxide insulating matrix. Our investigations are focused on the anomalous Hall effect (AHE) resistivity Rh and longitudinal resistivity R at T=5-200 K on the metallic side of metal-insulator transition in samples with the metal content x=49-56 at.%, that nominally corresponds to (Co40Fe40B20)x(Al2O3)100-x in the formula approximation. The conductivity at T > 15 K follows the lnT behavior that matches a strong tunnel coupling between nanogranules. It is shown that the scaling power-laws between AHE resistivity and longitudinal resistivity strongly differ, if temperature T or metal content x are variable parameters: Rh(T)~R(T)^0.4-0.5 obtained from the temperature variation of R and Rh at fixed x, while Rh(x)/x~R(x)^0.24, obtained from measurements at the fixed low temperature region (10-40 K) for samples with different x. We qualitatively describe our experimental data in the frame of phenomenological model of two sources of AHE e.m.f. arising from metallic nanogranules and insulating tunneling regions, respectively, at that the tunneling AHE (TAHE) source is strongly shunted due to generation of local circular Hall currents. We consider our experimental results as the first experimental proof of the TAHE manifestation.

cond-mat.mes-hall↗

arXiv2015

Grain-size dependent high-temperature ferromagnetism of polycrystalline MnxSi1-x (x~0.5) films

We present the results of a comprehensive study of magnetic, magneto-transport and structural properties of nonstoichiometric MnxSi1-x (x=0.51-0.52) films grown by the Pulsed Laser Deposition (PLD) technique onto Al2O3(0001) single crystal substrates at T = 340°C. A highlight of our PLD method is the using of non-conventional (shadow) geometry with Kr as a scattering gas during the sample growth. It is found that studied films exhibit high-temperature (HT) ferromagnetism (FM) with the Curie temperature TC ~ 370 K accompanied by positive sign anomalous Hall effect (AHE); they also reveal the layered polycrystalline structure with a self-organizing grain size distribution. The HT FM order is originated from the bottom interfacial nanocrystalline layer, while the upper layer possesses the low temperature (LT) type of FM order with TC = 46 K, gives essential contribution to the magnetization below 50 K and is homogeneous on the nanometer size scale. Under these conditions, AHE changes its sign from positive to negative at T < 30 K. We attribute observed properties to the synergy of self-organizing distribution of MnxSi1-x crystallites in size and peculiarities of defect-induced FM order in PLD grown polycrystalline MnxSi1-x (x~0.5) films.

cond-mat.mes-hall↗

arXiv2010

Room temperature ferromagnetism and anomalous Hall effect in Si$_{1-x}$Mn$_x$ ($x\approx 0.35$) alloys

A detailed study of the magnetic and transport properties of Si$_{1-x}$Mn$_x$ ($x\approx 0.35$) films is presented. We observe the anomalous Hall effect (AHE) in these films up to room temperature. The results of the magnetic measurements and the AHE data are consistent and demonstrate the existence of long-range ferromagnetic (FM) order in the systems under study. A correlation of the AHE and the magnetic properties of Si$_{1-x}$Mn$_x$ ($x\approx 0.35$) films with their conductivity and substrate type is shown. A theoretical model based on the idea of a two-phase magnetic material, in which molecular clusters with localized magnetic moments are embedded in the matrix of a weak itinerant ferromagnet, is discussed. The long-range ferromagnetic order at high temperatures is mainly due to the Stoner enhancement of the exchange coupling between clusters through thermal spin fluctuations (paramagnons) in the matrix. Theoretical predictions and experimental data are in good qualitative agreement.

cond-mat.mes-hall↗

arXiv2010

Room temperature ferromagnetism and anomalous Hall effect in Si_{1-x}Mn_x (x = 0.35) alloys

A detailed study of the magnetic and transport properties of Si1-xMnx (X = 0.35) films is presented. We observe the anomalous Hall effect (AHE) in these films up to room temperature. The results of the magnetic measurements and the AHE data are consistent and demonstrate the existence of long-range ferromagnetic (FM) order in the systems under study. A correlation of the AHE and the magnetic properties of Si1-xMnx (X = 0.35) films with their conductivity and substrate type is shown. A theoretical model based on the idea of a two-phase magnetic material, in which molecular clusters with localized magnetic moments are embedded in the matrix of a weak itinerant ferromagnet, is discussed. The long-range ferromagnetic order at high temperatures is mainly due to the Stoner enhancement of the exchange coupling between clusters through thermal spin fluctuations ("paramagnons") in the matrix. Theoretical predictions and experimental data are in good qualitative agreement.

cond-mat.mes-hall↗