A. A. Fraerman

Publications (35)23.29 Total impact

• Source

  Available from: S. N. Vdovichev

  Dataset: Magnetization controlled effects in overlap Josephson junctions coupled with submicron magnetic dots

  A A Fraerman, B A Gribkov, S A Gusev, A Y Klimov, Y N Nozdrin, V V Rogov, A V Samokhvalov, S N Vdovichev, L Fritzsch, E Ili'chev, R Stolz
• Article: Optical activity in media with noncoplanar magnetization distribution

  E. A. Karashtin, O. G. Udalov, A. A. Fraerman
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  ABSTRACT: Natural optical activity in magnetic media for which the exchange interaction dominates is studied theoretically. It is shown using a phenomenological theory that the optical activity effect can be observed in a medium with a nonuniform noncoplanar magnetization distribution without an inversion center. A microscopic theory of the optical activity is constructed for a medium with a helicoidal magnetic structure.
  Journal of Experimental and Theoretical Physics 04/2012; 109(6):973-978. · 1.03 Impact Factor
• Article: Magnetization reversal of elliptic Co/Si/Co nanodisks in the field of a magnetic-force microscope probe

  V. L. Mironov, A. A. Fraerman, B. A. Gribkov, O. L. Ermolaeva, S. A. Gusev, S. N. Vdovichev
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  ABSTRACT: The processes of local magnetization reversal of elliptic Co/Si/Co nanodisks under the action of a nonuniform magnetic field of a magnetic-force microscope (MFM) probe have been investigated. The specific features of the distribution of the phase MFM contrast from particles with ferromagnetic and antiferromagnetic configurations of the magnetic moments in neighboring Co layers have been discussed. It has been shown experimentally that, under the action of the probe field, there occur orientational transitions of two types: transitions from the ferromagnetic configuration to the antiferromagnetic configuration due to the reorientation of the magnetization of the upper layer and transitions in the antiferromagnetic configuration with a change in the orientation of the magnetic moment in both ferromagnetic layers. The presented results of micromagnetic simulation of the processes of transformation of the magnetization in such particles under the action of the MFM probe field explain the main regularities of the magnetization reversal processes.
  Physics of the Solid State 04/2012; 52(11):2297-2302. · 0.71 Impact Factor
• Article: Fabrication and magnetic force microscopy (MFM) observation of nano scale ferromagnetic nanodot arrays

  Joonyeon Chang, Wanghyun Park, A. A. Fraerman, V. L. Mironov
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  ABSTRACT: A novel electron beam lithography technique was utilized to fabricate nano scale magnetic dots array with high periodicity. C60 film (fullerine) was used as an electron beam sensitive resist for electron beam patterning carried out under a high accelerating voltage of 200 kV in a transmission electron microscope with a scanning mode. 50 nm sized permalloy (Py) nanodot arrays were successfully fabricated using the method followed by ion-milling. An array of Co nanodots having a size of 100×70 nm was alternatively prepared by liftoff instead of ion milling so as to prevent surface damage by ion milling. Lift-off does not yield any surface roughness, which is important for device fabrication. Magnetic force microscopy (MFM) observations were carried out on the fabricated Co nanodot arrays. A single domain state could be realized in patterned Co nanodots. MFM tip induced magnetization effects were also clearly demonstrated in the array of Co nanodots.
  Metals and Materials International 04/2012; 11(5):415-419. · 1.18 Impact Factor
• Article: Photogalvanic effect in ferromagnets with a noncoplanar magnetization distribution

  A. A. Fraerman, O. G. Udalov
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  ABSTRACT: The photogalvanic effect in ferromagnetic materials is predicted. This is the appearance of the direct electric current in a ferromagnet sample due to a high-frequency alternating electric field. The phenomenological theory of this photogalvanic effect in ferromagnets is developed and the simplest microscopic model explaining the occurrence of the photogalvanic effect in a medium with the helical magnetic structure is proposed. The photogalvanic effect arises owing to the breaking of the symmetry with respect to the reversal of the electron motion in the medium with a noncoplanar magnetization distribution. PACS numbers72.25.Ba–72.40.+w
  JETP Letters 04/2012; 87(3):159-163. · 1.35 Impact Factor
• Article: Control of the magnetic state of arrays of ferromagnetic nanoparticles with the aid of the inhomogeneous field of a magnetic-force-microscope probe

  V. L. Mironov, A. A. Fraerman, B. A. Gribkov, O. L. Ermolayeva, A. Yu. Klimov, S. A. Gusev, I. M. Nefedov, I. A. Shereshevskii
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  ABSTRACT: The work presents a survey of the results of studies of the processes of magnetization reversal of ferromagnetic nanoparticles under the action of the field of a magnetic force microscope probe. Keywordsmagnetic force microscopy–ferromagnetic nanoparticles–micromagnetism
  The Physics of Metals and Metallography 04/2012; 110(7):708-734. · 0.54 Impact Factor
• Article: Non-reciprocal light scattering by lattice of magnetic vortices

  O. G. Udalov, M. V. Sapozhnikov, E. A. Karashtin, B. A. Gribkov, S. A. Gusev, E. V. Skorohodov, V. V. Rogov, A. Yu. Klimov, A. A. Fraerman
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  ABSTRACT: We report on experimental study of optical properties of two-dimensional square lattice of triangle Co and CoFe nanoparticles with a vortex magnetization distribution. We demonstrate that intensity of light scattered in diffraction maxima depends on the vorticity of the particles magnetization and it can be manipulated by applying an external magnetic field. The experimental results can be understood in terms of phenomenological theory.
  04/2012;
• Source

  Available from: arxiv.org

  Article: Non-reciprocity in elastic unpolarized neutron scattering by systems with non-coplanar magnetic structure

  D. A. Tatarsky, O. G. Udalov, A. A. Fraerman
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  ABSTRACT: The paper provides a theoretical analysis for elastic unpolarized neutron scattering by systems having a non-coplanar magnetic induction spatial distribution. It is shown that reciprocity does not hold for neutron scattered by these systems. The scattering of unpolarized neutrons by a system of three magnetic mirrors and by a ferromagnetic particle in a "vortex" state is also explored.
  01/2011;
• Source

  Available from: S. N. Vdovichev

  Article: Magnetic force microscope tip-induced remagnetization of CoPt nanodisks with perpendicular anisotropy

  V. L. Mironov, B. A. Gribkov, S. N. Vdovichev, S. A. Gusev, A. A. Fraerman, O. L. Ermolaeva, A. B. Shubin, A. M. Alexeev, P. A. Zhdan, C. Binns
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  ABSTRACT: We report on the results of a magnetic force microscopy investigation of remagnetization processes in arrays of CoPt nanodisks with diameters of 35 and 200 nm and a thickness of 9.8 nm fabricated by e-beam lithography and ion etching. The controllable magnetization reversal of individual CoPt nanodisks by the magnetic force microscope (MFM) tip-induced magnetic field was demonstrated. We observed experimentally two essentially different processes of tip-induced remagnetization. Magnetization reversal of 200 nm disks was observed when the probe moved across the particle while in case of 35 nm nanodisks one-touch remagnetization was realized. Micromagnetic modeling based on the Landau–Lifshitz–Gilbert (LLG) equation demonstrated that the tip-induced magnetization reversal occurs through the essentially inhomogeneous states. Computer simulations confirmed that in case of 200 nm disks the mechanism of embryo nucleation with reversed magnetization and further dynamic propagation following the probe moving across the particle was realized. On the other hand one-touch remagnetization of 35 nm disks occurs through the inhomogeneous vortexlike state. Micromagnetic LLG simulations showed that magnetization reversal in an inhomogeneous MFM probe field has a lower energy barrier in comparison with the mechanism of coherent rotation, which takes place in a homogeneous external magnetic field.
  Journal of Applied Physics 10/2009; · 2.17 Impact Factor
• Source

  Available from: S. A. Gusev

  Article: Anti-vortex state in cross-like nanomagnets

  V. L. Mironov, O. L. Ermolaeva, S. A. Gusev, A. Yu. Klimov, V. V. Rogov, B. A. Gribkov, A. A. Fraerman, O. G. Udalov, R. Marsh, C. Checkley, R. Shaikhaidarov V. T. Petrashov
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  ABSTRACT: We report on results of computer micromodelling of anti-vortex states in asymmetrical cross-like ferromagnetic nanostructures and their practical realization. The arrays of cobalt crosses with 1 mkm branches, 100 nm widths of the branches and 40 nm thicknesses were fabricated using e-beam lithography and ion etching. Each branch of the cross was tapered at one end and bulbous at the other. The stable formation of anti-vortex magnetic states in these nanostructures during magnetization reversal was demonstrated experimentally using magnetic force microscopy. Comment: 19 pages, 9 figures
  09/2009;
• Article: "Topological" Hall effect in the ferromagnetic microparticles with noncoplanar magnetization distribution

  O. G. Udalov, A. A. Fraerman
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  ABSTRACT: The phenomenological theory for "topological" Hall effect (THE) is proposed. The theory can be used for qualitative analysis of THE in the medium with arbitrary magnetization distribution. In the paper the cylindrical particle with "vortex" magnetization is considered. The hysteresis loop of THE is qualitatively different comparing to abnormal Hall effect. The estimation of THE magnitude in the "vortex" particle is made. For Co particle with 100 nm diameter the THE exceeds normal and abnormal Hall effects until an external magnetic field less than 200 Oe. Comment: 4 pages, 4 figures
  07/2009;
• Article: Comparative x-ray reflectometry and atomic force microscopy of surfaces with non-Gaussian roughness

  V. L. Mironov, O. G. Udalov, B. A. Gribkov, A. A. Fraerman
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  ABSTRACT: Theoretical and experimental investigations have been carried out with the aim of comparing atomic force microscopy (AFM) and x-ray reflectometry (XRR) as methods for characterizing surface roughness. It is shown that AFM gives more appropriate information about the surface roughness in comparison to XRR. The method for estimating the parameters that characterize x-ray scattering on the basis of AFM data is developed.
  Journal of Applied Physics 10/2008; · 2.17 Impact Factor
• Article: Magnetotransport properties of GaMnAs with ferromagnetic nanodots

  Jooyoung Suh, Joonyeon Chang, Eun Kyu Kim, M. V. Sapozhnikov, V. L. Mironov, A. A. Fraerman
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  ABSTRACT: The new hybrid device consisting of single array of Co nanodots on top of GaMnAs is presented to explore a new functionality of GaMnAs diluted magnetic semiconductor (DMS). Magnetic state of Co dots was observed by magnetic force microscopy (MFM). Magnetoresistance of pure GaMnAs microbridge strongly depends on the orientation of applied magnetic field. Magnetization reversal of the single domain state definitely affects the longitudinal magnetoresistance of GaMnAs. Inhomogeneous magnetic field induced by Co nanodot is a dominant contribution to the resistance change. This field was regarded to act as an effective potential that may affect the spin polarized carriers in GaMnAs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
  Physica Status Solidi (A) Applications and Materials 04/2008; 205(5):1043 - 1046. · 1.46 Impact Factor
• Article: Magnetization controlled effects in overlap Josephson junctions coupled with submicron magnetic dots

  A A Fraerman, B A Gribkov, S A Gusev, A Y Klimov, Y N Nozdrin, V V Rogov, A V Samokhvalov, S N Vdovichev, L Fritzsch, E Ili'chev, R Stolz
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  ABSTRACT: The effect of submicron ferromagnetic particle on the field-dependent critical current of a short overlap Josephson junction is experimentally studied. Strong reversible variations of the maximum critical current are observed depending on the magnetic state of the particle. Pronounced commensurability effects are detected due to the presence of the additional peaks in the magnetic field induced diffraction pattern. The changes in the Fraunhofer pattern of the Josephson junctions are account for the formation of Abrikosov vortices trapped in the electrodes and inducing a phase inhomogeneity in the junction area.
  Journal of Physics Conference Series 03/2008; 97(1):012233.
• Article: Effect of ferromagnetic nanoparticles on the transport properties of a GaMnAs microbridge

  M. V. Sapozhnikov, A. A. Fraerman, S. N. Vdovichev, B. A. Gribkov, S. A. Gusev, A. Yu. Klimov, V. V. Rogov, Joonyeon Chang, Hyungjun Kim, Hyun Cheol Koo, Suk-Hee Han, S. H. Chun
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  ABSTRACT: A chain of Co nanoparticles was formed along a GaMnAs microbridge by electron beam lithography. The magnetic state of the particles was manipulated by a magnetic force microscope probe. It was found that resistance of the microbridge depended on the state of the particles and was different for the particles in the single-domain and vortex states. The resistance exhibited steplike behavior in an external magnetic field. This behavior was the result of the effect of the inhomogeneous stray fields of the particles on the microbridge resistance. The observed phenomenon can be used as an alternative way to control GaMnAs transport properties.
  Applied Physics Letters 09/2007; · 3.84 Impact Factor
• Source

  Available from: B. Hjörvarsson

  Article: Artificial helical nanomagnets

  A. A. Fraerman, B. A. Gribkov, S. A. Gusev, B. Hjorvarsson, A. Yu. Klimov, V. L. Mironov, D. S. Nikitushkin, V. V. Rogov, S. N. Vdovichev, H. Zabel
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  ABSTRACT: We demonstrate the existence of a helical state in patterned multilayer nanomagnets. The artificial helimagnets consist of a stack of single domain ferromagnetic disks separated by insulating nonmagnetic spacers. The spiral state is shown to originate from the magnetostatic interaction between nearest and next nearest neighbouring single-domain disks in the stack. Since the magnetostatic interaction for such disks is rather strong, the helical state should be stable at room temperature. The helimagnets were fabricated from a [Co/Si]*3 multilayer using electron beam lithography. The helical state was confirmed by a magnetic stray field analysis using magnetic force microscopy.
  06/2007;
• Source

  Available from: arxiv.org

  Article: Diode Effect in the Medium with a Helical Magnetic Structure

  A. A. Fraerman, O. G. Udalov
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  ABSTRACT: The volt-ampere characteristics of a medium with helical magnetic structure are theoretically studied. Phenomenological and microscopic theories of a diode effect in such a medium are proposed. Diode effect appears only in the medium with noncoplanar magnetic structure. Two mechanisms for the diode effect are considered. They are electron energy spectrum asymmetry and electron scattering asymmetry.
  01/2007;
• Article: Specific features of neutron propagation in a medium with a helical magnetic structure

  A. A. Fraerman, O. G. Udalov
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  ABSTRACT: The features of neutron motion in a noncoplanar magnetic field have been considered in the example of a specific magnetization distribution in the form of a conical helix. The neutron reflectances for holmium crystals have been calculated. It is shown that, in the case of noncoplanar distribution of magnetic field in a crystal, the spin-flip neutron reflectance has an additional singularity.
  Bulletin of the Russian Academy of Sciences Physics 12/2006; 71(1):27-31.
• Article: Transitions between the states with uniform and vortex distributions of magnetization in ferromagnetic nanoparticles under the action of an inhomogeneous magnetic field

  V. L. Mironov, B. A. Gribkov, A. A. Fraerman, I. R. Karetnikova, S. N. Vdovichev, S. A. Gusev, I. M. Nefedov, I. A. Shereshevskii
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  ABSTRACT: Specific features of magnetization distribution in elliptical Co nanoparticles have been investigated by magnetic force microscopy. Reversible transitions (induced by the microscope magnetic probe) between the uniform and vortex magnetization states have been found. The possibility of controlling the vorticity direction in such particles is shown.
  Bulletin of the Russian Academy of Sciences Physics 12/2006; 71(1):48-51.
• Source

  Available from: S. N. Vdovichev

  Article: Magnetic state control of ferromagnetic nanodots by magnetic force microscopy probe

  Joonyeon Chang, V. L. Mironov, B. A. Gribkov, A. A. Fraerman, S. A. Gusev, S. N. Vdovichev
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  ABSTRACT: We present the magnetic state control of individual ferromagnetic nanodots under inhomogeneous magnetic field induced by the probe of magnetic force microscope (MFM). Arrays of submicron sized elliptical ferromagnetic Co and FeCr dots with different sizes and periods were fabricated to demonstrate addressable manipulation of magnetization. MFM observations show the magnetization reversal and processes of local remagnetization of individual ferromagnetic nanodots subjected to magnetic change. Computer simulation of magnetization processes under inhomogeneous magnetic field induced by MFM probe was performed on the base of Landau-Lifshitz-Gilbert equation for magnetization.
  Journal of Applied Physics 11/2006; 100(10):104304-104304-7. · 2.17 Impact Factor