Unusual positive exchange bias after Zero-Field cooling at room temperature in the Co-CoO film composed of amorphous Co + CoO and crystallized Co/CoO

Abstract

The exchange bias (EB) effect is the physical cornerstone of magnetic storage and spin valves. The traditional EB effect is always realized under cooling field at low temperatures, which greatly restricts the practical application of the EB effect. In this work, an unusual positive EB effect after the zero-field cooling can be observed in Co-CoO film at room-temperature. The reason for this phenomenon is that the film is composed of crystallized Co/CoO and amorphous Co + CoO, and thus there is an exchange interaction between ferromagnetic, antiferromagnetic and uncompensated antiferromagnetic.