Fast Two-stage Protector Against Electromagnetic Pulse Based on Electroresistance Effect in Polycrystalline La-Sr(Ca)-Mn-O Films

摘要

The electroresistance (ER) effect in polycrystalline films of La0.83Sr0.17MnO3 and La0.7Ca0.3MnO3 was investigated in the temperature range of (5 – 290)?K using high power sub-nanosecond rise time electrical pulses with amplitude up to 1?kV. It was obtained that conductance vs. voltage dependences are nonlinear and could be well fitted by empirical formula G = G0 + Gα · Uα; where G is conductance, U is the voltage applied across the sample, G0 is the conductance at low voltage, and Gα and α are the parameters related to the electrical transport mechanism. Parameters α for La-Ca-Mn-O and La-Sr-Mn-O were 1.5 and 1.33 respectively. It was obtained that there are two regions of the electroresistance vs. temperature dependence for both films: low temperature region where ER exhibits very slow dependence on temperature and high temperature region where ER significantly decreases with temperature. It was demonstrated that polycrystalline manganite films can be used for the development of protectors against short electromagnetic pulse (EMP), and fast two-stage protector operating at cryogenic temperatures (80?K) is proposed.