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Marco Coisson - One of the best experts on this subject based on the ideXlab platform.

  • WiSNet - Tunable frequency ferromagnetic resonance of Co nanowire arrays
    2013 IEEE Topical Conference on Wireless Sensors and Sensor Networks (WiSNet), 2013
    Co-Authors: Massimo Pasquale, Elena Olivetti, Carlo Paolo Sasso, Marco Coisson
    Abstract:

    In order to overcome the current limitations of metallic systems for microwave applications, columnar arrays of Co nanowires with variable wire lengths were electrochemically grown using anodic alumina membranes with thickness of ~100 μm and pore diameters around 70 nm. The Co nanowires tend to present a strong hcp-magnetocrystalline anisotropy directed in the plane perpendicular to the wires axis. The combination of shape anisotropy directed along the wire axis (depending on the wire length) and the hcp magneto-crystalline anisotropy (due to structure) causes a shift from in-plane to out-of-plane spontaneous Magnetization with relevant saturation and Remanence Magnetization values. Different types of magnetic behavior may then lead to ferromagnetic resonance frequencies shifting from 20 to 40 GHz at zero applied field.

  • RWS - Tunable frequency ferromagnetic resonance of Co nanowire arrays
    2013 IEEE Radio and Wireless Symposium, 2013
    Co-Authors: Massimo Pasquale, Elena Olivetti, Carlo Paolo Sasso, Marco Coisson
    Abstract:

    In order to overcome the current limitations of metallic systems for microwave applications, columnar arrays of Co nanowires with variable wire lengths were electrochemically grown using anodic alumina membranes with thickness of ~100 μm and pore diameters around 70 nm. The Co nanowires tend to present a strong hcp-magnetocrystalline anisotropy directed in the plane perpendicular to the wires axis. The combination of shape anisotropy directed along the wire axis (depending on the wire length) and the hcp magneto-crystalline anisotropy (due to structure) causes a shift from in-plane to out-of-plane spontaneous Magnetization with relevant saturation and Remanence Magnetization values. Different types of magnetic behavior may then lead to ferromagnetic resonance frequencies shifting from 20 to 40 GHz at zero applied field.

  • Tunable frequency ferromagnetic resonance of Co nanowire arrays
    2013 IEEE 13th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2013
    Co-Authors: Massimo Pasquale, Elena Olivetti, Carlo Paolo Sasso, Marco Coisson
    Abstract:

    In order to overcome the current limitations of metallic systems for microwave applications, columnar arrays of Co nanowires with variable wire lengths were electrochemically grown using anodic alumina membranes with thickness of ~100 μm and pore diameters around 70 nm. The Co nanowires tend to present a strong hcp-magnetocrystalline anisotropy directed in the plane perpendicular to the wires axis. The combination of shape anisotropy directed along the wire axis (depending on the wire length) and the hcp magneto-crystalline anisotropy (due to structure) causes a shift from in-plane to out-of-plane spontaneous Magnetization with relevant saturation and Remanence Magnetization values. Different types of magnetic behavior may then lead to ferromagnetic resonance frequencies shifting from 20 to 40 GHz at zero applied field.

Krzysztof Kułakowski - One of the best experts on this subject based on the ideXlab platform.

  • Remanence and switching sensitivity in nanodot magnetic arrays
    arXiv: Materials Science, 2006
    Co-Authors: Przemysław Gawroński, Krzysztof Kułakowski
    Abstract:

    New results are reported of the computer simulations on the magnetic behaviour of magnetic arrays of nanoscopic dots, placed in cells of the square lattice. We show that the Remanence Magnetization $M_r$ decreases with the array size. For arrays 50x50, we investigate also the stability of the magnetic structure of an array in an oscillating magnetic field. The damage spreading technique reveals that this stability increases with the standard deviation $\sigma$ of the switching field of individual elements of the array. On the other hand, $M_r$ decreases with $\sigma$. An optimalization of the system (large $M_r$ and large stability) can then be reached at some intermediate value of $\sigma$.

  • Stress dependence of bistability in a zero-magnetostrictive amorphous wire
    Journal of Materials Science, 2004
    Co-Authors: Julian Gonzalez, Krzysztof Kułakowski, P. Aragoneses, J.m. Blanco, E. Irurieta
    Abstract:

    New data on the bistability of (Co95Fe5)72.5Si12.5B15 amorphous wire are discussed in the framework of a simple model of magnetic interaction between inner core and outer shell of a wire. Experimental results are reported on the tensile stress and annealing-time dependence of switching field and Remanence Magnetization, for longitudinal and circular hysteresis loops. Theoretical considerations allow various scenarios of the bistability effect to be distinguished, which are helpful in our understanding of the experimental data.

  • Stress dependence of bistability in Co-based amorphous wires
    Journal of Magnetism and Magnetic Materials, 1996
    Co-Authors: Krzysztof Kułakowski, Julian Gonzalez, P. Aragoneses
    Abstract:

    Abstract Recent results on the thermal treatment and applied stress dependence of magnetic bistability of Co72.5Si12.5B15 amorphous wires are discussed in terms of a propagation mechanism of switching. The spatial distribution of the magnetic anisotropy energy is evaluated from experimental data on the switching field. The contributions from the inner core and the outer shell to the Remanence Magnetization are separated by means of model calculations. The calculated influence of stress annealing on the Remanence Magnetization is found to agree qualitatively with new experimental data.

  • Influence of applied torsion on the bistable behavior of CoSiB amorphous wire
    Journal of Applied Physics, 1994
    Co-Authors: J.m. Blanco, P. Aragoneses, E. Irurieta, J. Gonzalez, Krzysztof Kułakowski
    Abstract:

    Experimental results are reported on the torsion dependence of bistability of CoSiB amorphous alloys. Switching field and Remanence Magnetization are measured with applied torsion up to 20π rad/m for as‐quenched wire as well as for stress‐annealed wire, with and without preannealing. Measurements are performed both for Mz‐Hz and Mz‐Hφ hysteresis loop. The results show that the bistability of Co‐rich amorphous wire strongly depends on the torsion‐induced helical anisotropy.

N V Kudrevatykh - One of the best experts on this subject based on the ideXlab platform.

  • Low-Temperature Magnetic Hysteresis in Nd(Pr)-Fe-B Nanostructured Alloys with Nd2Fe14B Type Main Phase Composition
    Defect and Diffusion Forum, 2018
    Co-Authors: Dmitriy Sergeevich Neznakhin, G. A. Politova, L. A. Ivanov, A.s. Volegov, Denis I. Gorbunov, I. S. Tereshina, N V Kudrevatykh
    Abstract:

    Magnetic hysteresis properties of nanostructured industrially manufactured Nd-Fe-B and Pr-Fe-B alloys on the base of a tetragonal Nd2Fe14B (2-14-1) hard magnetic phase (MQP-B, MQP-B+ and MQP-16-7 brands) have been investigated at 4.2 K in magnetic fields up to 58 T. The chemical composition of the alloys given in the certificates was defined more precisely. The grain sizes of the main 2-14-1 phase were determined. The average grain size is much smaller than a critical single domain diameter. Coercivity, Remanence Magnetization, saturation Magnetization and maximal magnetic energy product were determined at 4.2 K and compared with those obtained at room temperature.

  • intergrain exchange interaction estimation from the Remanence Magnetization analysis
    Journal of Magnetism and Magnetic Materials, 2015
    Co-Authors: A S Bolyachkin, Aleksey Volegov, N V Kudrevatykh
    Abstract:

    Abstract Analysis of δ m ( H ) = [ M d ( H ) − M r ( ∞ ) + 2 M r ( H ) ] / M r ( ∞ ) curves constructed from dc deMagnetization and isothermal remanent Magnetization ( M d ( H ) and M r ( H ) respectively) is important for characterization of the interactions in ferromagnets. Up to now, it has been mainly used for qualitative deductions about them. In this work, the novel functional relation between the maximum of the δ m ( H ) plot and the microscopic parameters of the weakly coupled Stoner–Wohlfarth ensemble with the isotropic distribution of easy Magnetization axes was established using computer modeling. It allows quantitative analysis in the frame of the model to be performed. Finally, a new method of estimating the intergrain exchange interaction constant for nanostructured high anisotropy magnets could be formulated taking into account the results of the modeling.

Mochamad Zainuri - One of the best experts on this subject based on the ideXlab platform.

  • Crystal Structure and Magnetic Properties of Zn doped Barium M-Hexaferrite
    Advanced Materials Research, 2015
    Co-Authors: Umi Nuraini, Lita Amalia, Kurniawati C. Rosyidah, Mochamad Zainuri
    Abstract:

    Synthesis of Zn doped Barium M-Hexaferrite (BaFe12-xZnxO19) has been performed by co-precipitation method. The purified iron sand from Tulungagung is used as a precursor of Fe3O4. Synthesis of Zn doped Barium M-Hexaferrite (BaFe12-xZnxO19) with variations of x = 0.3, 0.5, and 0.7 wt % has been calcined at temperatures of 1000°C for 5 hours. Ion Zn2+ (with 0 ≤ x ≤ 0.7 wt %) does not change the crystal structure of Barium M-Hexaferrite (BaM), but give a slight displacement of the peak position of the diffraction pattern. SEM figures showed that Zn doped Barium M-Hexaferrite (BaFe12-xZnxO19) have a hexagonal structure, similar to BaM structure. Doping of Zn has changed the magnetic properties of Barium M-Hexaferrit (BaM), from hard magnetic become soft magnetic. Barium M-Hexaferrit (BaM) has a value of Coercivity Field (Hc) and Remanence Magnetization (Mr) is 0.03734 T and 8.334 emu/g. At variation x = 0.3, the Remanence Magnetization (Mr) reaches the highest value. At this point, a value of Coercivity Field (Hc) and Remanence Magnetization (Mr) is 0.0506 T and 14.782 emu/gram respectively.

  • Crystal Structure and Magnetic Properties of Zn doped Barium M-Hexaferrite
    Jurnal Fisika dan Aplikasinya, 2014
    Co-Authors: Umi Nuraini, Lita Amalia, Kurniawati C. Rosyidah, Mochamad Zainuri
    Abstract:

    Synthesis of Zn doped Barium M-Hexaferrite (BaFe12−xZnxO19) has been performed by coprecipitation method. The purified iron sand from Tulungagung is used as a precursor of Fe3O4. Synthesis of Zn doped Barium M-Hexaferrite with variations of x = 0.3, 0.5, and 0.7 has been calcined at temperatures of 1000C for 5 hours. Ion Zn2+ (with 0 x 0.7 wt %) does not change the crystal structure of Barium M-Hexaferrite (BaM), but give a slight displacement of the peak position of the diffraction pattern. SEMfigures showed that Zn doped Barium M-Hexaferrite have a hexagonal structure, similar to BaM structure. Doping of Zn has changed the magnetic properties of Barium M-Hexaferrit (BaM), from hard magnetic become soft magnetic. Barium M-Hexaferrit (BaM) has a value of Coercivity Field (Hc) and Remanence Magnetization (Mr) is 0.03734 T and 8.334 emu/g. At variation x = 0.3, the Remanence Magnetization (Mr) reaches the highest value. At this point, a value of Coercivity Field (Hc) and Remanence Magnetization (Mr) is 0.0506 T and 14.782 emu/gram respectively.

Carmine Vittoria - One of the best experts on this subject based on the ideXlab platform.

  • First observation of magnetoelectric effect in M-type hexaferrite thin films
    Journal of Applied Physics, 2013
    Co-Authors: Marjan Mohebbi, Khabat Ebnabbasi, Carmine Vittoria
    Abstract:

    The magnetoelectric (ME) effect in M-type hexaferrite thin films is reported. Prior to this work, the ME effect in hexaferrite materials was observed only in bulk polycrystalline materials. Thin films of SrCo2Ti2Fe8O19 were grown on sapphire (0001) using pulsed laser deposition. The thin films were characterized by X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy, vibrating sample magnetometer, and ferromagnetic resonance. We measured saturation Magnetization of 1250 G, g-factor of 2.66, and coercive field of 20 Oe for these magnetoelectric M-type hexaferrite thin films. The magnetoelectric effect was confirmed by monitoring the change rate in Remanence Magnetization with the application of DC voltage at room temperature and it gave rise to changes in Remanence in the order of 12.8% with the application of only 1 V (DC voltage). We deduced a magnetoelectric coupling, α, of 6.07 × 10−9 s m–1 in SrCo2Ti2Fe8O19 thin films.The magnetoelectric (ME) effect in M-type hexaferrite thin films is reported. Prior to this work, the ME effect in hexaferrite materials was observed only in bulk polycrystalline materials. Thin films of SrCo2Ti2Fe8O19 were grown on sapphire (0001) using pulsed laser deposition. The thin films were characterized by X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy, vibrating sample magnetometer, and ferromagnetic resonance. We measured saturation Magnetization of 1250 G, g-factor of 2.66, and coercive field of 20 Oe for these magnetoelectric M-type hexaferrite thin films. The magnetoelectric effect was confirmed by monitoring the change rate in Remanence Magnetization with the application of DC voltage at room temperature and it gave rise to changes in Remanence in the order of 12.8% with the application of only 1 V (DC voltage). We deduced a magnetoelectric coupling, α, of 6.07 × 10−9 s m–1 in SrCo2Ti2Fe8O19 thin films.

  • Strong magnetoelectric coupling in hexaferrites at room temperature
    Journal of Applied Physics, 2013
    Co-Authors: Khabat Ebnabbasi, Marjan Mohebbi, Carmine Vittoria
    Abstract:

    In this paper, the magnetoelectric effect in single-crystalline Sr Z-type hexaferrite materials is reported. The measurements include material characterization and change in Remanence Magnetization (Mr) versus electric field. In a very low electric field equal to 3.75 V/cm, 14% change in Mr was observed. We deduced a magneto-electric coupling of 55.4 in CGS units or 2.32 × 10−6 sm−1 (SI units) which is the highest value measured to date.

  • Room Temperature Magnetoelectric Effects on Single Slabs of Z-type Hexaferrites
    arXiv: Materials Science, 2011
    Co-Authors: Khabat Ebnabbasi, Yajie Chen, Anton L. Geiler, Vincent G. Harris, Carmine Vittoria
    Abstract:

    In this paper, magnetoelectric effects of Sr Z-type hexaferrite, Sr3Fe24Co2O41, at room temperature is measured. The change in Remanence Magnetization was measured by applying a DC voltage or electric field across a slab of hexaferrite. Changes of ~ 18% in Remanence was observed in an electric field of 10,000V/cm implying a similar change in the microwave permeability at frequencies below 3GHz. In these types of measurements high resistivity is critical in order to reduce current flow in the hexaferrite. The resistivity of the hexaferrite was raised to 4.28x10^8 ohm?-cm by annealing under oxygen pressure. The measurements indicate that indeed electric polarization and Magnetization changes were induced by the application of magnetic and electric fields, respectively. The implications for microwave applications appear to be very promising at room temperature.