Research Papers in Physics and Astronomy
Title
Direct Observation of the Magnetic Anisotropy of an Fe (II) Spin Crossover Molecular Thin Film
Date of this Version
2023
Citation
Ashley S. Dale et al 2023 J. Phys. Mater. in press https://doi.org/10.1088/2515-7639/ace21a
Abstract
Spin crossover molecules are a promising candidate for molecular spintronics that aim for ultrafast and low-power devices for data storage and magnetic and information sensing. The rapid spin state transition is best controlled by non-thermal methods including magnetic field. Unfortunately, the magnetic field normally required to switch the spin state is normally high (~30 T), which calls for better understanding of the fundamental mechanism. In this work, we provide clear evidence of magnetic anisotropy in the local orbital moment of a molecular thin film based on spin crossover 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-switching mechanism in the presence of magnetic perturbations.
Comments
Open access.