Probing orbital and spin moments of electron-beam-sensitive magnetic oxides via high-energy transmission electrons

Magnetic oxides host rich spin-orbit-coupled phenomena central to data storage and quantum technologies, yet near-atomic quantification of their spin and orbital moments remains challenging, obscuring origins of phenomena. Electron magnetic circular dichroism (EMCD) provides a unique solution, while many oxides suffer electron-induced valence changes that corrupt spectral fidelity, imposing long-standing limitations on high-resolution moment investigation. On a widely-used yet beam-irradiation-susceptible oxide CoFe 2 O 4 , we demonstrate an EMCD methodology addressing this challenge. First, a dose strategy tailoring the dose rate was proposed to preserve spectral fidelity. Second, an optimized EMCD geometry with a joint-parameter post-processing (JPP) method and an artifact correction method was developed to overcome the conflict between oxides’ low tolerance of electron dose and EMCD’s intrinsic demand of high dose. An example statistical analysis demonstrated that JPP method reduced background-related error of Fe orbital-to-spin ratio from 0.18 ± 0.04 to 0.12 ± 0.01, and the correction method further improved it to 0.065 ± 0.005, in high-resolution low-dose cases. These developments enable simultaneous detection of reliable EMCD signal of Fe and Co in model CoFe 2 O 4 , indicating the potential of revealing subtle variations in magnetic microstructures. Our methodology unlocks high-resolution spin-orbit-coupling research in beam-sensitive magnetic oxides.