High Pulsed Magnetic Field Sensor Based on La-Ca-Mn-O Thin Polycrystalline Films

Abstract

It is demonstrated that polycrystalline La 0.33 Ca 0.67 MnO 3 thin film sensors can be used to measure pulsed strong magnetic fields with microsecond duration rise and decay times. The response characteristics of these sensors were investigated using 0.7-1.0 ms duration bell-shaped magnetic field pulses of 10-20 T amplitudes and by using special waveform magnetic field pulses with amplitudes of 40 T and decay times of 50 µs. The response of these magnetic field sensors was compared with those of conventional loop sensors and Faraday rotation sensors using Bi 12 SiO 20 single crystals as a known standard.

Velocity-induced current profiles inside the rails of an electric launcher

“…In recent years, the discovery of the colossal magnetoresistance in manganite materials has led to the development of the so-called CMR-B-scalar sensor [13], [14]. This sensor type is very small and can be used to measure the absolute value of pulsed magnetic flux densities up to 40 T. An array of such sensors was successfully used to investigate the current distribution in the rails of a railgun by measuring the magnetic field distribution in the vicinity of the rail [15]- [17].…”

Thin Film Manganite-Metal Interconnection and "Loop Effect" Studies in CMR-Based High Magnetic Field Sensors

“…The coefficients k 1 and k 2 calculated using data from Fig. 2b was 11.34 and 0.625 mV/T, respectively, that give f max ≈ 1.5 kHz according to (1). The f max can be increased biasing sensor by higher voltage, however this way has a limitation due to Joule's heating dissipated in magnetic material.…”

“…It was demonstrated that the colossal magnetoresistance (CMR)-B-scalar sensor can be successfully used for high pulsed magnetic field measurements [1,2]. The sensor is a two-terminal device with thin manganite film as material sensitive to magnetic flux density (B) magnitude.…”

Magnetic Diffusion in Railguns: Measurements Using CMR-Based Sensors

“…The CMR is a result of the magnetic ordering of the material on the microscopic level and, in general, is sensitive to the magnitude of the magnetic field. However, it was found that the 0018-9464/$25.00 © 2009 IEEE CMR effect in epitaxial manganite films saturates in intermediate magnetic fields (10-15 T) [8] while the magnetoresistance of polycrystalline manganites has no tendency of saturation [9], [10] up to 50 T. Furthermore, the anisotropy of magnetoresistance and hysteresis are observed in epitaxial manganite films while magnetoresistance of polycrystalline films grown at certain conditions is independent of the direction of the magnetic field [11]. These advantages of polycrystalline films were used to design magnetic-field sensors for measuring the magnitude of magnetic fields (B-scalar sensors) independently on their direction.…”