Temperature and thickness dependent magnetostatic properties of [Fe/Py]/FeMn/Py multilayers
D.M. Polishchuk1,2, O. I. Nakonechna1,3, Ya. M. Lytvynenko1, V. Kuncser4, Yu. O. Savina5, V. O. Pashchenko5, A. F. Kravets1, A. I. Tovstolytkin1,3
1Institute of Magnetism of the NAS of Ukraine and MES of Ukraine, Kyiv 03142, Ukraine
2Nanostructure Physics, Royal Institute of Technology, Stockholm 10691, Sweden
3Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
4National Institute of Materials Physics, Bucharest-Magurele 077125, Romania
5B. Verkin Institute for Low Temperature Physics and Engineering, of the National Academy of Sciences of Ukraine Kharkiv 61103, Ukraine pos Анотація:812
Received February 24, 2021, published online April 26, 2021
The magnetic properties of thin-film multilayers [Fe/Py]/FeMn/Py are investigated as a function of temperature and thickness of the antiferromagnetic FeMn spacer using SQUID magnetometry. The observed behavior differs substantially for the structures with 6 nm and 15 nm FeMn spacers. While the 15 nm FeMn structure exhibits exchange pinning of both ferromagnetic layers in the entire measurement temperature interval from 5 to 300 K, the 6 nm FeMn structure becomes exchange de-pinned in the vicinity of room temperature. The de-pinned state is characterized by a single hysteresis loop centered at zero field and having enhanced magnetic coercivity. The observed properties are explained in terms of finite-size effects and possible ferromagnetic inter-layer coupling through the thin antiferromagnetic spacer.
Key words: antiferromagnet nanostructures, interlayer coupling, exchange bias, magnetic proximity effect, magnetic multilayer.