Tuning the antiferromagnetic ground state of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>Ce</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mi>RhIn</mml:mi> <mml:mn>8</mml:mn> </mml:msub> </mml:mrow> </mml:math> by Ga substitution
Bibliographic record
Abstract
We explore the effect of Ga substitution on the physical properties of single crystals of ${\mathrm{Ce}}_{2}{\mathrm{RhIn}}_{8}$ through measurements of temperature-dependent specific heat, magnetic susceptibility, and electrical resistivity. Our data on ${\mathrm{Ce}}_{2}{\mathrm{RhIn}}_{8\ensuremath{-}x}{\mathrm{Ga}}_{x}$, single crystals reveal a monotonic decrease of the antiferromagnetic transition temperature from ${T}_{N}=2.77$ K for the parent compound to ${T}_{N}$ = 1.96 K for the highest Ga concentration achieved ($x=0.55$). To understand the evolution of the crystalline electric field (CEF) scheme and exchange interactions as a function of Ga substitution, we fit our thermodynamic data to a Hamiltonian containing a tetragonal CEF term and mean-field isotropic exchange terms. Our results show a systematic increase in the energies of the first and second excited states as a function of Ga concentration. Moreover, we find significant changes to the CEF ground-state (GS) wave function ($\mathrm{\ensuremath{\Gamma}}=\ensuremath{\alpha}\ensuremath{\mid}\ifmmode\pm\else\textpm\fi{}5/2\ensuremath{\rangle}+\sqrt{1\ensuremath{-}{\ensuremath{\alpha}}^{2}}\ensuremath{\mid}\ensuremath{\mp}3/2\ensuremath{\rangle}$), including an increase in the $\ensuremath{\alpha}$ coefficient and in the $\ensuremath{\mid}{B}_{2}^{0}\ensuremath{\mid}$ CEF parameter, with increasing Ga concentration. This evolution of the GS wave function drives the system away from the quantum critical point, whereas the chemical pressure associated with the Ga substitution drives the system towards it. Such behavior raises the question of whether pressure-induced superconductivity can be stabilized in this system. Our electrical resistivity and heat capacity measurements on ${\mathrm{Ce}}_{2}{\mathrm{RhIn}}_{7.64}{\mathrm{Ga}}_{0.36}$ under hydrostatic pressure reveal a zero-resistance state; however, no bulk superconductivity is detected. These results suggest that the occurrence of bulk superconductivity may be unfavorable in this system due to the observed CEF GS wave-function evolution and/or to the pair-breaking mechanism in the ${\mathrm{Ce}}_{2}{\mathrm{RhIn}}_{8\ensuremath{-}x}{\mathrm{Ga}}_{x}$ series.
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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 | 0.000 | 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".