Magnetic properties of multilayered CoO-ZnO

ORAL

Abstract

The magnetic character of CoO/ZnO multilayers is investigated at low temperature (2 - 100K). Multilayers of CoO/ZnO, with varying nominal thickness of antiferromagnetic insulating (111) cubic CoO (0.7 -- 1.6 nm) and semiconducting (002) wurtzite ZnO:Al semiconductor (0.4 -- 2.0 nm), were prepared on c-cut sapphire substrate at 550 C by rf-magnetron reactive sputtering. Magnetic, transport, and magnetotransport measurements were carried out over a temperature range of 2 to 100 K. CoO( $\sim $1.4 nm)/ZnO( $\sim $0.7 nm) shows ferromagnetism with small moment up to 100 K. Up to 10 K there is clear ferromagnetic hysteresis in the out of plane direction and no magnetic hysteresis in-plane. For thicker ZnO, no magnetic properties are observed. We suggest that at low temperature the uncompensated spins in the CoO antiferromagnetic layers are coupled by exchange interaction through the ZnO:Al layer. This research was supported by both DOE and WIN.

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Authors

  • Hyeon-Jun Lee

    Department of Physics, University of California Berkeley, Department of Physics, University of California, Berkeley

  • Frances Hellman

    University of California, Berkeley, University of California at Berkeley, Berkeley, CA, Departments of Physics and Materials Science and Engineering, University of California Berkeley, Department of Physics, University of California, Berkeley