COMMENSURABILITY OSCILLATIONS BY RUNAWAY AND PINNED ELECTRONS

We report on an investigation of commensurability oscillations in anti dot square-lattices, and show that the commensurate peaks in resistivi ty rho(xx) derive from two kinds of electron: runaway and quasipinned electrons. The runaway electrons, which skip away along the antidot ar rays, increase the value of conductivity sigma(xx); and the quasipinne d electrons, which orbit some antidots for a long time, decrease the v alue of sigma(xx). Therefore, by competition between the two different types of electron, the conductivity sigma(xx) is determined. The cond uctivity sigma(yx) in the antidot lattice always has dips at the peaks in rho(xx). As a result, by combining the of values of sigma(xx) and sigma(yx), the resistivity is determined through the orthodox relation of rho(xx) = sigma(xx)/(sigma(xx)(2) + sigma(yx)(2)). (C) 1998 Academ ic Press Limited.