%0 Journal Article
%A KAUSHIK, SONIA
%A Raj, Rakhul
%A Gupta, Pooja
%A Chumakov, Andrei
%A Schwartzkopf, Matthias
%A Reddy, V. Raghavendra
%A Kumar, Dileep
%T Growth-induced magnetic anisotropy in Co/C<sub>60</sub> bilayers: Insights from a two-grain Stoner-Wohlfarth model
%J Physical review / B
%V 111
%N 18
%@ 2469-9950
%C Woodbury, NY
%M PUBDB-2025-04393
%P 184426
%D 2025
%X Organic spintronics has gained significant interest within the scientific community due to its potential applications in spin-valve devices. However, the realization of an efficient room-temperature organic spin-valve device remains elusive, primarily due to the complex spin transport at metal-organic interfaces. Hence, the study of these metal-organic bilayer interfaces is essential for the conception of such devices. This study investigates the Co-C<sub>60</sub> interface and its impact on the magnetic properties of the Co layer. We examine the structural and magnetic properties of ultrathin cobalt (Co) films deposited on a fullerene (C<sub>60</sub>) layer to understand the origin of magnetic anisotropy in metal-organic bilayer structures. The penetration of ferromagnetic Co atoms into the C<sub>60</sub> film is confirmed through x-ray reflectivity and secondary-ion-mass spectroscopy. Additionally, grazing incidence small-angle x-ray scattering and atomic force microscopy provide ample insights into the morphological properties of the Co/C<sub>60</sub> bilayers. Grazing incidence x-ray diffraction and grazing incidence wide-angle x-ray scattering confirm the texturing of Co in the bilayer at higher cobalt thicknesses. Angular-dependent magneto-optic Kerr effect hysteresis measurements, with varying Co layer thicknesses, reveal information about growth-induced uniaxial magnetic anisotropy. Unlike inorganic silicon substrates, where Co texturing and magnetic anisotropy are absent, magnetic anisotropy in Co films begins to develop at a thickness of 25 Å on the C<sub>60</sub> layer and increases with further cobalt deposition. This texturing induces a dispersion in magnetic anisotropy, leading to an anomalous increase in coercivity and remanence along the hard axis. The anomalous behavior in coercivity and remanence variation along the nominal hard axis is explained by the two-grain Stoner-Wohlfarth model and is further corroborated by the nonuniform spatial distribution of magnetic domains observed through Kerr microscopy. Our simulations show that these magnetic anomalies arise due to the formation of local energy minima in the energy landscape near the nominal hard axis.   
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1103/PhysRevB.111.184426
%U https://bib-pubdb1.desy.de/record/639292