Long-range exchange coupling in Co/Nb/Co trilayers

Long-range interlayer exchange coupling (IEC) in multilayers has been a topic of extensive research, both experimental and theoretical. IEC can be induced by two ferromagnetic (FM) layers spaced by a thin non-magnetic (NM) material. In this work, we performed vector model Vibrating Sample Magnetometer (V-VSM), Magneto-optic Kerr effect and magnetoresistance (MR) measurements as a function of temperature from 1K up to room temperature. Interestingly, we observed an oscillatory behavior of the magnetic coercive field usually associated with IEC without fully antiferromagnetic compensation of the ferromagnetic layers at all temperatures. This may suggest an additional Long-range exchange coupling mechanism beyond the direct exchange.