Dale, Ashley S.Yazdani, SaeedEkanayaka, Thinlini K.Mishra, EshaHu, YuchenDowben, Peter A.Freeland, John W.Zhang, JianCheng, Ruihua2024-02-142024-02-142023-07Dale, A. S., Yazdani, S., Ekanayaka, T. K., Mishra, E., Hu, Y., Dowben, P. A., Freeland, J. W., Zhang, J., & Cheng, R. (2023). Direct observation of the magnetic anisotropy of an Fe(II) spin crossover molecular thin film. Journal of Physics: Materials, 6(3), 035010. https://doi.org/10.1088/2515-7639/ace21ahttps://hdl.handle.net/1805/38528In this work, we provide clear evidence of magnetic anisotropy in the local orbital moment of a molecular thin film based on the SCO complex [Fe(H2B(pz)2)2(bipy)] (pz = pyrazol−1−yl, bipy = 2,2'−bipyridine). Field dependent x-ray magnetic circular dichroism measurements indicate that the magnetic easy axis for the orbital moment is along the surface normal direction. Along with the presence of a critical field, our observation points to the existence of an anisotropic energy barrier in the high-spin state. The estimated nonzero coupling constant of ∼2.47 × 10−5 eV molecule−1 indicates that the observed magnetocrystalline anisotropy is mostly due to spin–orbit coupling. The spin- and orbital-component anisotropies are determined to be 30.9 and 5.04 meV molecule−1, respectively. Furthermore, the estimated g factor in the range of 2.2–2.45 is consistent with the expected values. This work has paved the way for an understanding of the spin-state-switching mechanism in the presence of magnetic perturbations.en-USAttribution 4.0 Internationalanisotropyg factormagnetic propertiesspin crossoverspin transitionsArticle