Colossal negative magnetoresistance in a two-dimensional electron gas

Magnetoresistance quantum oscillations in a magnetic two-dimensional electron gas

J. Kunc,1,2,* B. A. Piot,1 D. K. Maude,1 M. Potemski,1 R. Grill,2 C. Betthausen,3 D. Weiss,3 V. Kolkovsky,4 G. Karczewski,4 and T. Wojtowicz4 1Laboratoire National des Champs Magnétiques Intenses (LNCMI), CNRS-UJF-UPS-INSA, 38042 Grenoble, France 2Institute of Physics, Faculty of Mathematics and Physics, 12116 Prague, Czech Republic 3Experimentelle und Angewandte Physik, Universität Regensburg,...

Negative hopping magnetoresistance of two-dimensional electron gas in a smooth random potential.

We show that the tunnel coupling between semiclassical states localized in different minima of a smooth random potential increases when magnetic field is applied. This increase originates from the difference in gauge factors which electron wave functions belonging to different electron “lakes” acquire in the presence of the field. We illustrate the increase of coupling by a model calculation of...

Colossal magnetoresistance

We review recent experimental work falling under the broad classification of colossal magnetoresistance (CMR), which is magnetoresistance associated with a ferromagnetic-toparamagnetic phase transition. The prototypical CMR compound is derived from the parent compound, perovskite LaMnO3. When hole doped at a concentration of 20–40% holes/Mn ion, for instance by Ca or Sr substitution for La, the...

Colossal Magnetoresistance

Colossal magnetoresistance (CMR) effect was discovered among the manganese oxide class of materials, i.e. La1−xCaxMnO3. It shows large magnetoresistance by orders of magnitude, however several environmental requirements limit CMR toward general applications. Recently people have been focused on understanding a fundamental physics because of complex correlations between electron-lattice and elec...

Colossal Magnetoresistance