Strong exchange bias by a single layer of independent antiferromagnetic grains: The CoO/Co model system

Abstract

CoO/Co bilayers with only 20 \AA{} thin CoO reveal an extremely strong exchange bias characterized by magnetic hysteresis loops of rectangular shape and an ideal dependence on Co layer thickness. Quantitative information on important structural and magnetic parameters are given including the exact lateral size and shape of the fine grains constituting the films and a characteristic temperature dependence of the exchange bias. The high coupling energy originates from a single dense layer of independent antiferromagnetic grains in connection with a large number of uncompensated spins in the CoO.