Modulating Exchange Bias, Anisotropic Magnetoresistance, and Planar Hall Resistance of Flexible Co/MnN Epitaxial Bilayers on Mica by Bending Strain

Zuolun Chen; Xiang Liu; Jiawei Jiang; Rui Li; Yue Wang; Liu Guo; Yingdan Xu; Wenbo Mi

doi:10.1021/acsami.2c21780

Modulating Exchange Bias, Anisotropic Magnetoresistance, and Planar Hall Resistance of Flexible Co/MnN Epitaxial Bilayers on Mica by Bending Strain

ACS Appl Mater Interfaces. 2023 Feb 1;15(4):6209-6216. doi: 10.1021/acsami.2c21780. Epub 2023 Jan 18.

Authors

Zuolun Chen¹, Xiang Liu², Jiawei Jiang¹, Rui Li¹, Yue Wang¹, Liu Guo¹, Yingdan Xu¹, Wenbo Mi¹

Affiliations

¹ Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin300354, China.
² College of Science, Civil Aviation University of China, Tianjin300300, China.

PMID: 36654188
DOI: 10.1021/acsami.2c21780

Abstract

The integration of ferromagnetic/antiferromagnetic bilayers with exchange bias effect on flexible substrates is crucial for flexible spintronics. Here, the epitaxial Co/MnN bilayers are deposited on mica by facing-target sputtering. A large in-plane exchange bias field (H_EB) of 1800 Oe with a coercive field (H_C) of 2750 Oe appears in the Co (3.8 nm)/MnN (15.0 nm) bilayer at 5 K after field cooling from 300 to 5 K. Effective interfacial exchange energy J_eff of the Co/MnN bilayer is 0.83 erg/cm². The strain-induced maximum increase of H_EB and H_C reaches 18% and 21%, respectively, in the Co(3.8 nm)/MnN(15.0 nm) bilayer. Strain-modulated H_EB is attributed to the change of interfacial exchange coupling between Co and MnN layers. H_EB is inversely proportional to Co thickness but independent of MnN thickness. The change of H_EB is less than 5% after 100 bending cycles, indicating mechanical durability. The out-of-plane exchange bias also appears since Co spins are not fully reversed due to the strong pinning effect. Anisotropic magnetoresistance (AMR) and planar Hall resistance (R_xy) show obvious hysteresis due to H_EB. Exchange bias-induced phase difference of AMR and R_xy almost remains unchanged at different bending strains. The results provide the basis for understanding the bending strain tailored exchange bias.

Keywords: Co/MnN bilayer; anisotropic magnetoresistance; exchange bias; flexible spintronics; planar Hall resistance.