Observation of magnetic breakdown in double quantum wells

✍ Scribed by N.E. Harff; J.A. Simmons; J.F. Klem; G.S. Boebinger; L.N. Pfeiffer; K.W. West

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 113 KB
• Volume: 20
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1006/spmi.1996.0120

✦ Synopsis

We report on our studies of magnetic breakdown (MB) in coupled GaAs/Al 0.3 Ga 0.7 As double quantum wells (DQWs) subject to crossed magnetic fields. MB is a failure of semiclassical theory that occurs when a magnetic field causes electrons to tunnel across a gap in k-space from one Fermi surface (FS) branch to another. We study MB in a two-branch FS created by subjecting a DQW to an in-plane magnetic field (B ). The principal effect of B is a distortion in the dispersion curve of the system, yielding a FS consisting of two components, a lens-shaped inner orbit and an hour-glass-shaped outer orbit. The perpendicular field (B ⊥ ) causes Landau level formation and Shubnikov-de Haas (SdH) oscillations for each branch of the FS. At higher perpendicular fields MB occurs and electrons tunnel through k-space from one FS orbit to the other. MB is observed by noting which peaks are present in the Fourier power spectrum of the magnetoresistance versus 1/B ⊥ at constant B . We observe MB in two DQW samples over a range of B .