Temperature- and magnetic field-dependence of exchange bias in SrCoO2.29 ceramics

A cation’s oxidation state in a transition metal oxide may significantly change its physical and chemical properties. In this work, magnetic properties of both cubic SrCoO2.29 and hexagonal SrCoO2.50 ceramics, annealed following a selected yet simple process, have been studied. The SrCoO2.50 ceramics annealed in air displays an unusual paramagnetic property, and the SrCoO2.29 quenched into water shows a short-range ferromagnetic coupling in the antiferromagnetic background. Exchange coupling at the ferromagnetic/antiferromagnetic interfaces brings out an obvious exchange bias effect in the SrCoO2.29 sample. Due to its complicated magnetic states, the exchange bias effect presents strong temperature and cooling field dependences.