The magnetoresistance of thin polycrystalline La_{1-x}Sr_{x}MnO_{3} films deposited on lucalox substrate using metal organic chemical vapor deposition technique was investigated in pulsed magnetic fields up to 18 T in the temperature range 100-320 K. The influence of film preparation conditions, ambient temperature variation and Sr content is analyzed in order to determine the optimal conditions for the design of CMR-B-scalar magnetic field sensor based on thin manganite film, operating at room temperature.
The design, technology and main characteristics of Ag contacts as well as "loop effect" peculiarities of colossal magnetoresistance B-scalar high magnetic field sensor based on La_{1-x}(Ca)Sr_x MnO_3 films used for measuring high magnetic field pulses are presented.
The effects of strong pulsed electric field on the electrical properties of thin epitaxial La_{0.7}Sr_{0.3}MnO_3 films were investigated. The fast electrical switching from high resistance off-state to low resistance on-state was obtained at current densities higher than 10^6 A/cm^2. This current was able to induce an irreversible damage of the sample in the regions at the edges of the electrodes of the film. It was demonstrated that thermal effects are responsible for appearance of delay time and asymmetrical shape of current channel in on-state, however, the fast switching from off- to on-state is a result of electronic effects appearing when critical power is reached in the film.
The resistance, magnetoresistance, and resistance response under microwave irradiation (f=10 and 35 GHz) were measured for epitaxial and polycrystalline La_{0.67}Ca_{0.33}MnO_3 and La_{0.67}Sr_{0.33}MnO_3 thin films in the temperature range 78÷300 K. The microwave induced resistance increase observed for the epitaxial films in a narrow temperature range below the ferromagnetic to paramagnetic transition temperature T_c certifies coexistence of low resistance (ferromagnetic) and high resistance (paramagnetic) regions in the manganites. Resistance of polycrystalline films decreased under microwave irradiation in a wide temperature range below T_c. The effect was explained in terms of microwave assisted hopping of carriers in high resistance regions formed at grain boundaries of the polycrystalline films.
The magnetoresistance anisotropy of ultrathin La_{0.83}Sr_{0.17}Mn O_3 films deposited on NdGaO_3 substrate by metalorganic chemical vapour deposition technique was investigated. The electric-field-induced resistance change was studied up to electric fields of 10 kV/cm using ns duration electrical pulses. It was found that in ultrathin (< 10 nm) and thin (< 50 nm) films the origin of electric-field-induced resistance change is thermal. However, the films with thicknesses of about 20 nm, exhibit negative electric-field-induced resistance change, having a pure electronic nature. This effect is explained in terms of two-layer systems with imperfections located at the interface between the layers.
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