Reorientation of anisotropy in a square well quantum hall sample.
We have measured magnetotransport at half-filled high Landau levels in a quantum well with two occupied electric subbands. We find resistivities that are isotropic in perpendicular magnetic field but become strongly anisotropic at nu = 9/2 and 11/2 on tilting the field. The anisotropy appears at an in-plane field, B(ip) approximately 2.5 T, with the easy-current direction parallel to B(ip) but rotates by 90 degrees at B(ip) approximately 10 T and points now in the same direction as in single-subband samples. This complex behavior is in quantitative agreement with theoretical calculations based on a unidirectional charge density wave state model.
Pan
W
W
Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Jungwirth
T
T
Stormer
H L
HL
Tsui
D C
DC
MacDonald
A H
AH
Girvin
S M
SM
Smrcka
L
L
Pfeiffer
L N
LN
Baldwin
K W
KW
West
K W
KW