Exchange bias in Fe/EuTe(111) bilayers

Abstract

We report on the investigation of the exchange bias effect in Fe layers on EuTe͑111͒, an antiferromagnetic semiconductor. For this ferromagnet ͑FM͒/semiconducting antiferromagnet ͑AFM͒ exchange bias system, we have found positive and negative exchange bias effect ͑EB͒. Fresh samples exhibit positive EB, independently of the applied cooling field, indicating antiferromagnetic coupling between the FM and the AFM layers at the Fe/EuTe͑111͒ interface. The change in EB with time, from positive EB for fresh samples to negative EB after short time,is attributed to aging effects at the Fe/EuTe interface.

Adjusting exchange bias and coercivity of magnetic layered systems with varying anisotropies

“…Finally, it provides a novel explanation for the positive exchange bias and the theoretical base which has frequently been discussed in the literature. [6][7][8] This effect has been attributed to a parallel coupling of FM and AFM moments at the interface due to large cooling fields, [9][10][11] antiferromagnetic coupling at the interface, [12][13][14][15] a mainly antiferromagnetic parallel domain wall which is "unwinding" before zero field, 16 spin-glass-like particles formed spontaneously at the interface, 17 or to reversible changes in the interfacial pinning by the antiferromagnet causing an asymmetric magnetization reversal. 18 What is proposed here, however, is the simple possibility to obtain positive exchange bias in a special EB system without the need to consider directly any effects on an atomic scale.…”