Abstract:
We have studied the magnetoresistance oscillation (Weiss oscillation) in
a two-dimensional electron gas (2DEG) subjected to a one-dimensional periodic
modulation of magnetic field. Magnetic field modulation was produced by
placing nickel grating on the surface of 2DEG wafer and applying a magnetic
field $B_{\parallel}$ {\it parallel}\/ to the 2DEG plane. We show that
the amplitude of the magnetic modulation
can be varied by rotating $B_{\parallel}$
with respect to the grating, independent of the perpendicular field $B_{\perp}$
used for the measurement of magnetoresistance. With decreasing magnetic
modulation amplitude, the magnetoresistance oscillation loses its amplitude
without shifting the phase, until peak-to-valley inversion takes place.
This demonstrates that the magnetic modulation thus produced are spatially
out-of-phase with the small residual electrostatic potential modulation
inevitably brought about by the grating.