No abstract

A three-layer magnetoelectric composite PZT / FeRh / PZT consisting of a layer of a magnetic alloy Fe 49 Rh 51 and two layers of a piezoelectric lead zirconate PbZr 0.53 Ti 0.47 O 3 was fabricated and its magnetic properties were studied. The magnetic alloy Fe 49 Rh 51 from which the magnetic layer was made was obtained by induction melting from pure rhodium Rh (99.9 %) and iron Fe (99.98 %). An X-ray diffraction analysis of the alloy showed the predominance of a B2 type phase with a bcc structure with an impurity phase of type α' with a fcc structure. Elemental analysis confirmed the composition corresponding to Fe 49 Rh 51. Temperature dependences of magnetic susceptibility were measured in two regimes: with piezoelectric layers under voltage ("switch on") and without voltage ("switch off "). In the "switch off " regime a phase transition at 324 K in heating and at 315 K in cooling is observed that is different from the results for pure Fe 49 Rh 51. Application of a voltage to the opposite faces of the composite induces a mechanical stress on the magnetic layer that leads to a decrease in the magnetic susceptibility and shift of the transition temperatures to 320 K in heating and 316 K in cooling. Moreover, this mechanical stress changes the shape and area of the hysteresis, which can be used for control of magnetic properties of materials. The magnetic properties and temperature hysteresis with applied electric field have been theoretically considered and explained on the basis of the Landau-Khalatnikov equations.

The bi- and tri- layered magnetoelectric composites were fabricated from magnetic Fe49Rh51 and piezoelectric PbZr0.53Ti0.47O3 materials. It was shown the electric field-induced stresses reduce the magnetization around magnetic phase transition temperature of Fe49Rh51: by 5.4% for tri-layer PZT/FeRh/PZT composite and by 3.6% for bi-layer FeRh/PZT composite. The magnetoelectric properties were studied at 320 K, the magnetization rate was estimated for the magnetic field of 0.5 T. The heterogeneous distributions of stresses and magnetization in volume of magnetic layer under applied magnetic and electric fields were demonstrated using COMSOL Multiphysics software. The obtained results demonstrate the tri-layered composite is more effective for tuning the magnetization

No abstract

No abstract

We report the results of studies of the magnetic and transport properties of Fe49Rh51 alloy prepared by different sequences of quenching and the annealing process. The temperature dependences of the relative initial magnetic permeability and resistivity are analyzed. An optimal regime consisting of annealing at 1300 K for 440 min and quenching from 1300 K to 275 K is found to observe the desired narrow antiferromagnetic–ferromagnetic transition in Fe49Rh51 alloy under cyclic conditions. This has the potential to increase the efficiency of cooling devices based on the magnetocaloric effect of magnetic materials with a first-order field-induced phase transition.

The tunable magnetic properties of amorphous ferromagnetic glass-coated microwires make them suitable for a wide range of applications. Accurate knowledge of the micromagnetic structure is highly desirable since it affects almost all magnetic properties. To select an appropriate wire-sample for a specific application, a deeper understanding of the magnetization reversal process is required, because it determines the measurable response (such as induced voltage waveform and its spectrum). However, the experimental observation of micromagnetic structure of micro-scale amorphous objects has strict size limitations. In this work we proposed a novel experimental technique for evaluating the microstructural characteristics of glass-coated microwires. The cross-sectional permeability distribution in the sample was obtained from impedance measurements at different frequencies. This distribution enables estimation of the prevailing anisotropy in the local region of the wire cross-section. The results obtained were compared with the findings of magnetostatic measurements and remanent state analysis. The advantages and limitations of the methods were discussed.

No abstract