TMR study of GaMnAs/AlGaAs:Be/GaMnAs trilayers

ORAL

Abstract

GaMnAs/GaAs:Be/GaMnAs trilayers have recently demonstrated antiferromagnetic (AFM) coupling between the two ferromagnetic (FM) layers, mediated by holes in the spacer layer. In this work, GaMnAs/Al$_{x}$Ga$_{1-x}$:Be/GaMnAs trilayer samples with varying Al concentrations were fabricated into magnetic tunnel junction (MTJ) devices with range of pillar diameters to measure tunneling magnetoresistance (TMR) under various conditions. SQUID measurements were use to measure the magnetization of the samples, including switching fields for parallel and antiparallel magnetization alignments of the FM layers. TMR was observed in the sample with Al$_{0.22}$Ga$_{0.78}$As:Be spacer, but was massively suppressed in the samples with lower Al content. The presence of holes in the spacer layer is shown to suppress TMR. This illustrates the difference in conditions for TMR and for AFM interlayer coupling.

*Supported by NSF Grant DMR-1005851 and OISE-1015458.

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Authors

  • Joseph Hagmann

    • Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA

  • Xinyu Liu

    • Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA

  • Malgorzata Dobrowolska

    • Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA

  • Jacek Furdyna

    • Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA

  • Taehee Yoo

    • Department of Physics, Korea University, Seoul 136713, South Korea

  • Sungwon Khym

    • Department of Physics, Korea University, Seoul 136713, South Korea

  • Sanghoon Lee

    • Department of Physics, Korea University, Seoul 136713, South Korea