Colossal magnetoresistance

About: Colossal magnetoresistance is a research topic. Over the lifetime, 3658 publications have been published within this topic receiving 130104 citations.

Electric and magnetic modulation of fully strained dead layers in La(0.67)Sr(0.33)MnO(3) films

Abstract: We report the electrical transport and magnetic properties of the dead layer of La(0.67)Sr(0.33)MnO(3) grown on LaAlO(3) substrate under the influence of magnetic field and electric voltage. The electrical resistance of the dead layer shows exponential decrease with both magnetic field and electric voltage, leading to colossal magnetoresistance and electroresistance, respectively. However, the sample cannot be driven into a metallic state with the available magnetic field and electric voltage. At low temperatures, the magnetic-field dependence of both magnetization and resistance show remarkable hysteresis. Exchange bias effect was observed in the magnetization vs magnetic-field curves. Magnetic force microscope measurement reveals the coexistence of different magnetic phases in the dead layer. The results were discussed in terms of phase separation in the dead layer. This work demonstrates the presence of phase separation in the manganite dead layer and its tunability by magnetic field and electric voltage.

Temperature dependence of magnetoresistance and nonlinear conductance of the bicrystal grain boundary in epitaxial La0.67Ba0.33MnO3 thin films

Abstract: We investigated conduction through an artificial grain-boundary junction made in La0.67Ba0.33MnO3 thin films, deposited on a 36.7° SrTiO3 bicrystal substrate using a laser ablation technique. The grain boundary exhibits substantial magnetoresistance at low temperatures and also shows nonlinear I–V characteristics. Analysis of temperature dependence of the dynamic conductance allows us to identify three carrier transport mechanisms across the grain boundary. These mechanisms exist in parallel, and at a given temperature one mechanism may dominate. Particularly, at higher temperatures (T>175 K) the transport across the grain boundary involves spin–flip scattering, which we establish leads to decrease of the bicrystal grain-boundary contribution in magnetoresistance. At lower temperature (4.2–45 K), tunneling through a disordered oxide at the grain boundary dominates, whereas in the temperature range from 100 to 175 K, carrier transport is dominated by inelastic tunneling via pairs of manganese atoms.

Electronic transport and colossal electroresistance in SrTiO3:Nb-based Schottky junctions

Abstract: Current-voltage characteristics and colossal electroresistance (CER) have been experimentally investigated in the temperature range from 293 to 454 K for the Schottky junctions Au/SrTiO3:0.5 wt % Nb and Au/SrTiO3:0.05 wt % Nb. Both junctions show electron tunneling-dominated transport behavior. Postannealing of SrTiO3:0.05 wt % Nb in oxygen atmosphere causes a transition of the transport behavior from electron tunneling to thermionic emission. The CER effect appears in the junctions with the transport behavior dominated by electron tunneling and greatly weakens when thermionic emission prevails after postannealing. This result reveals the presence of a close relation between CER and electron tunneling.

Colossal negative magnetoresistance in a two-dimensional electron gas

Abstract: We report on a colossal negative magnetoresistance (MR) in a GaAs/AlGaAs quantum well which, at low temperatures, is manifested by a drop of the resistivity by more than an order of magnitude at a magnetic field $B\ensuremath{\approx}1$ kG. In contrast to MR effects discussed earlier, the MR reported here is not parabolic, even at small $B$, and persists to much higher in-plane magnetic fields and temperatures. Remarkably, the temperature dependence of the resistivity at $B\ensuremath{\approx}1$ kG is linear over the entire temperature range studied (from 1 to 30 K) and appears to coincide with the high-temperature limit of the zero-field resistivity, hinting on the important role of acoustic phonons.