Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 72: Low-Dimensional Systems: Poster Session
TT 72.10: Poster
Wednesday, March 18, 2015, 15:00–18:00, Poster B
Torque magnetometry on two-dimensional electron systems at MgZnO/ZnO interfaces — •Schorsch Michael Sauther1, Stephan Albert1, Matthias Brasse1, Joseph Falson2, Yusuke Kozuka2, Atsushi Tsukasaki3, Marc Andreas Wilde1, Masashi Kawasaki2,4, and Dirk Grundler1 — 1Phys.-Dep. E10, TU München — 2Dep. of App. Phys. and QPEC, University of Tokyo — 3IMR, Tohoku University and JST PRESTO — 4RIKEN CEMS
Two-dimensional electron systems (2DESs) in oxide heterostructures have created great interest in the recent years. We study the magnetization M of MgZnO/ZnO heterostructures with 2DESs of small carrier density and high mobility at low temperatures and in high magnetic fields B. We report the de Haas-van Alphen (dHvA) effect, non-equilibrium currents (NECs) and unexpected overshoots in M(B). An investigation of the temperature dependence of the dHvA amplitude allows us to determine the effective masses of the electron systems. We find enhanced effective masses and enhanced dHvA amplitudes. The NEC signals are analyzed regarding their dependence on temperature and magnetic field sweep rate. We explain the unexpected overshoots of the dHvA amplitude by means of the magnetic thaw-down effect which allows us to identify the type and density of charged impurities in the heterostructures. In addition, we report a hysteretic feature in the dHvA effect that we discuss in the framework of quantum Hall ferromagnetism. The work is supported by the DFG via TRR80 and Grant-in-Aids for Scientific Research (S) No. 24226002 from MEXT, Japan, as well as by the Murata Science Foundation.