Ten years of <scp>EMCD</scp> : what has been achieved
Bibliographic record
Abstract
Energy loss magnetic chiral dichroism (EMCD), established in 2006 [1] celebrates its 10 th anniversary. EMCD is the TEM equivalent of the X‐ray magnetic circular dichroism (XMCD) technique routinely applied on synchrotron beam lines for the study of magnetic moments. The EMCD signal is detected as an asymmetry in the energy filtered diffraction pattern, or alternatively as a slight difference in the fine structure of energy loss spectra for particular momentum transfers in the inelastic interaction (Fig. 1). The extremely high spatial resolution of modern TEMs makes EMCD interesting for spintronic and micromagnetic applications. In the last decade, the technique has evolved into a reliable tool demonstrating nm‐resolution, site selectivity and separation of spin and orbital moments via sum rules. One of the consequences of EMCD is that the outgoing inelastically scattered probe electrons have topological charge. Structurally, they are identical with vortex electrons that can be routinely created in the electron microscope [2]. Such vortices are characterized by a spiraling wavefront and a phase singularity at the center, similar to optical vortices that were first described by Nye & Berry [3]. Owing to their short wavelength, these matter waves can be focused to atomic size. Another novel aspect is their magnetic moment, quantized in multiples of the Bohr magneton, independent of the electron spin. These features make electron vortices extremely attractive as a nanoscale probe for magnetic materials. The discovery of vortex electron beams has spurred efforts to use them for EMCD because of their intrinsic chirality. It became soon clear that atom‐sized vortices are needed to achieve this goal [4], as shown in Fig. 2. At the time of writing, the closest successful approach to such beams is the shaping of the incident wave front with a Cs corrector such that it matches the point group symmetry of the selected atomic column, revealing EMCD signals with atomic resolution [5]. A promising alternative is the use of holographic vortex filters in the outgoing beam to detect spin polarized transitions [6], as sketched in Fig. 3. Other than in the standard EMCD geometry, this approach does not require a precise alignment of the crystal, and would thus allow the study of nanocrystalline and amorphous materials.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.005 |
| Scholarly communication | 0.004 | 0.008 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.003 | 0.005 |
| Insufficient payload (model declined to judge) | 0.016 | 0.008 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".