Origin of the enhanced ferroelectricity in multiferroic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>SmM</mml:mi><mml:msub><mml:mi mathvariant="normal">n</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math>
Bibliographic record
Abstract
In orthorhombic $\mathrm{SmM}{\mathrm{n}}_{2}{\mathrm{O}}_{5}$ single crystals, $\mathrm{S}{\mathrm{m}}^{3+}$ crystal-field (CF) excitations are studied by infrared transmission as a function of temperature and under applied magnetic field up to 10 T. These measurements are complemented with the study of Raman-active phonon frequency shifts as a function of temperature between 300 and 5 K. The frequencies of all $^{6}H_{j}$ crystal-field levels of $\mathrm{S}{\mathrm{m}}^{3+}$ were determined as well as those of $^{6}F_{j}$. At high temperatures, the evolutions of $\mathrm{S}{\mathrm{m}}^{3+}$ CF excitations exhibit anomalies around the characteristic temperatures, ${T}^{*}\ensuremath{\sim}60\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and ${T}^{\mathrm{S}}\ensuremath{\sim}120\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and reflect the thermal disorder induced by splitting of the Sm--O bonds in $\mathrm{SmM}{\mathrm{n}}_{2}{\mathrm{O}}_{5}$ that contribute to the frequency and linewidth phonon shifting. At low temperatures, the degeneracy of the ground-state Kramers doublet is lifted (${\mathrm{\ensuremath{\Delta}}}_{0}\ensuremath{\sim}36\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$) due to the $\mathrm{S}{\mathrm{m}}^{3+}\ensuremath{-}\mathrm{M}{\mathrm{n}}^{3+}$ interaction in the ferroelectric phase and strongly enhanced below ${T}_{\mathrm{C}}\ensuremath{\sim}26\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The Sm-Mn exchange interaction ${J}_{6}$ is determined and compared to that of Gd-Mn interaction in $\mathrm{GdM}{\mathrm{n}}_{2}{\mathrm{O}}_{5}$. The Sm magnetic moment ${m}_{\mathrm{Sm}}(T)$ and the Sm contribution to the magnetic susceptibility are also evaluated from ${\mathrm{\ensuremath{\Delta}}}_{0}(T)$, indicating that the Sm-Mn interaction is strongly implicated in the magnetic and the ferroelectric orderings below $\ensuremath{\sim}26\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The study of the $\mathrm{S}{\mathrm{m}}^{3+}$ CF excitations as a function of magnetic field reveals twinning in $\mathrm{SmM}{\mathrm{n}}_{2}{\mathrm{O}}_{5}$. This twinning could affect its electric polarization behavior versus magnetic field.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.005 |
| Meta-epidemiology (narrow) | 0.002 | 0.003 |
| Meta-epidemiology (broad) | 0.001 | 0.004 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.005 | 0.004 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.436 | 0.010 |
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; both teacher heads agree on what is shown here.
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".