Interlayer Exchange Coupling in Semiconductor EuS–PbS Ferromagnetic Wedge Multilayers

Antiferromagnetic interlayer coupling between ferromagnetic layers of EuS via nonmagnetic PbS spacer layer was experimentally studied in EuS– PbS wedge multilayers grown on KCl (001) substrates with EuS thickness of 6 nm and PbS thickness varying in the wedges in the range 0.3–6 nm (i.e. n = 1−20 monolayers). Measurements of magnetic hysteresis loops of EuS–PbS multilayers performed in the temperature range 5–30 K by superconducting (SQUID) and magneto-optical magnetometers revealed a rapid increase in saturation magnetic field in multilayers with PbS spacer thinner than about 1.5 nm. It shows a monotonic increase in interlayer coupling strength with a decreasing PbS spacer thickness, in qualitative agreement with 1/2 dependence predicted theoretically for semiconductor magnetic superlattices.