Observation of a new low-field minimum in magnetically modulated systems

Abstract

The magnetoresistance of a magnetically modulated two-dimensional electron gas (2DEG) shows a positive magnetoresistance at low fields, which can be ascribed to ‘snake orbits, traveling along contours of vanishing magnetic field. At slightly higher fields anomalies in the resistance result from the commensurability of the classical cyclotron orbit of the electrons at the Fermi energy and the period of the magnetic modulation. In our experiments we observed, besides the minimum at B=0, an additional minimum of the magnetoresistance at B=0.