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 CoFe₂O₄, 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 CoFe₂O₄, indicating the potential of revealing subtle variations in magnetic microstructures. Our methodology unlocks high-resolution spin-orbit-coupling research in beam-sensitive magnetic oxides.

Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed (hcp) structure, which fails to provide sufficient independent slip systems for homogeneous deformation. Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture. 〈c + a〉 slip, tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation, whereas the orientation dependence becomes less obvious with further increasing strain. The high work hardening rate at the strain of 2%–5% is accompanied by the significant increase of 〈c + a〉 slip and tension twinning activities. The fine microstructure strongly restricts the activation and growth of twinning, resulting in a slow exhaust of tension twinning and thin compression twins. The restriction of twinning and the activation of profuse 〈c + a〉 slip near grain/twin boundaries, relaxing the stress concentration, sustain the homogeneous deformation to a high strain.

Mg-3Gd (wt.%) samples with different initial grain sizes were prepared to evaluate the grain size effect on microstructural evolution during cold rolling and subsequent annealing hardening response. The deformation behavior and mechanical response of the as-rolled and annealed samples were systematically investigated by a combination of electron microscopy and microhardness characterization. The results show that the twinning activities were highly suppressed in the fine-grained samples during rolling. Upon increasing the rolling reduction to 40%, ultra-fine grain structures with a volume fraction of ∼28% were formed due to the activation of multiple slip systems. Conversely, twinning dominated the early stages of deformation in the coarse-grained samples. After a 10% rolling reduction, numerous twins with a volume fraction of ∼23% were formed. Further increasing the rolling reduction to 40%, high-density dislocations were activated and twin structures with a volume fraction of ∼36% were formed. The annealing hardening response of deformed samples was effectively enhanced compared to that of the non-deformed samples, which was attributed to the enhanced Gd segregation along grain boundaries, twin boundaries and dislocation cores. Moreover, the grain size and rolling reduction were found to affect the microstructure evolution during annealing, resulting in a notable difference in the annealing hardening response of Mg-3Gd alloy between samples of different grain sizes deformed to different strains. These findings highlight the crucial importance of microstructural and processing parameters in the design of high-strength, cost-effective Mg alloys.