Dichotomous dynamics of magnetic monopole fluids
Bibliographic record
Abstract
A recent advance in the study of emergent magnetic monopoles was the discovery that monopole motion is restricted to dynamical fractal trajectories [J. N. Hallén et al. , Science 378 , 1218 (2022)], thus explaining the characteristics of magnetic monopole noise spectra [R. Dusad et al., Nature 571 , 234 (2019); A. M. Samarakoon et al. , Proc. Natl. Acad. Sci. U.S.A. 119 , e2117453119 (2022)]. Here, we apply this novel theory to explore the dynamics of field-driven monopole currents, finding them composed of two quite distinct transport processes: initially swift fractal rearrangements of local monopole configurations followed by conventional monopole diffusion. This theory also predicts a characteristic frequency dependence of the dissipative loss angle for AC field–driven currents. To explore these novel perspectives on monopole transport, we introduce simultaneous monopole current control and measurement techniques using SQUID-based monopole current sensors. For the canonical material Dy 2 Ti 2 O 7 , we measure <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">Φ</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>t</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> , the time dependence of magnetic flux threading the sample when a net monopole current <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi>J</mml:mi> <mml:mfenced close=")" open="("> <mml:mi>t</mml:mi> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mover accent="true"> <mml:mi mathvariant="normal">Φ</mml:mi> <mml:mo>˙</mml:mo> </mml:mover> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>t</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo stretchy="false">/</mml:mo> <mml:msub> <mml:mi>μ</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> is generated by applying an external magnetic field <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mfenced close=")" open="("> <mml:mi>t</mml:mi> </mml:mfenced> <mml:mo>.</mml:mo> </mml:mrow> </mml:math> These experiments find a sharp dichotomy of monopole currents, separated by their distinct relaxation time constants before and after t ~ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mn>600</mml:mn> <mml:mo> </mml:mo> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> </mml:math> from monopole current initiation. Application of sinusoidal magnetic fields <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mfenced close=")" open="("> <mml:mi>t</mml:mi> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mi>B</mml:mi> <mml:mi mathvariant="normal">c</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> <mml:mfenced close=")" open="(" separators=""> <mml:mi>ω</mml:mi> <mml:mi>t</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> generates oscillating monopole currents whose loss angle <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi>θ</mml:mi> <mml:mfenced close=")" open="("> <mml:mi>f</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> exhibits a characteristic transition at frequency <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>f</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>1.8</mml:mn> <mml:mo> </mml:mo> <mml:mi mathvariant="normal">kHz</mml:mi> </mml:math> over the same temperature range. Finally, the magnetic noise power is also dichotomic, diminishing sharply after t ~ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mn>600</mml:mn> <mml:mo> </mml:mo> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> </mml:math> . This complex phenomenology represents an unprecedented form of dynamical heterogeneity generated by the interplay of fractionalization and local spin configurational symmetry.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".