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From magnetic order to valence-change crossover in EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ using He-gas pressure
by Bernd Wolf, Felix Spathelf, Jan Zimmermann, Theresa Lundbeck, Marius Peters, Kristin Kliemt, Cornelius Krellner, Michael Lang
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Submission summary
| Authors (as registered SciPost users): | Bernd Wolf |
| Submission information | |
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| Preprint Link: | scipost_202207_00023v1 (pdf) |
| Date submitted: | 2022-07-15 13:00 |
| Submitted by: | Wolf, Bernd |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | International Conference on Strongly Correlated Electron Systems (SCES2022) |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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Abstract
We present results of magnetic susceptibility and thermal expansion measurements performed on high-quality single crystals of EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ for 0 $\leq$ x $\leq$ 0.2 and temperatures 2 K $\leq T \leq$ 300 K. Data were taken at ambient pressure and finite He-gas pressure $p$ $\leq$ 0.5 GPa. For x = 0 and ambient pressure we observe a pronounced valence-change crossover centred around $T'_V$ $\approx$ 160 K with a non-magnetic ground state. This valence-change crossover is characterized by an extraordinarily strong pressure dependence of d$T'_V$ /d$p$ = (80 $\pm 10)$ K/GPa. We observe a shift of $T'_V$ to lower temperatures with increasing Ge-concentration, reaching $T'_V$ $\approx$ 90 K for x = 0.1, while still showing a non-magnetic ground state. Remarkably, on further increasing x to 0.2 we find a stable Eu$^{(2+\delta)+}$ valence with long-range antiferromagnetic order below $T_N$ = (47.5 $\pm$ 0.1) K, reflecting a close competition between two energy scales in this system. In fact, by the application of hydrostatic pressure as small as 0.1 GPa, the ground state of this system can be changed from long-range antiferromagnetic order for $p$ $<$ 0.1 GPa to an intermediate-valence state for $p$ $\geq$ 0.1 GPa.
Current status:
Reports on this Submission
Report #1 by Anonymous (Referee 1) on 2022-10-4 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202207_00023v1, delivered 2022-10-04, doi: 10.21468/SciPost.Report.5826
Strengths
1) the paper reports on new experimental data on the valence crossover in EuPd2(Si1-xGex)2 systems by measures of the magnetic susceptibility and thermal expansion at ambient and applied pressures.
2) The paper is clearly written and the results are pertinent.
Weaknesses
1) I recommend to put the legend in figs 3a) and fig 3). It is annoying to be forced to read the figure to see the legend.
2) The paper would profit from a plot of the doping, pressure, temperature phase diagram. I strongly recommend this for publication.
Report
As stated above the paper is clearly written and deserves publication in the proceedings of the SCES conference. However, I strongly recommend to show a phase diagram indicating the thermal expansion and susceptibility data under pressure.
Requested changes
1) legend in fig 3
2) additional figure (or as insert) of phase diagram indicating the phase lines AF, valence transition as function of pressure, concentration.
Author: Bernd Wolf on 2022-10-21 [id 2942]
(in reply to Report 1 on 2022-10-04)Anonymous Report 1 on 2022-10-4 (Invited Report) for scipost_202207_00023v1
„From magnetic order to valence-change crossover in EuPd2(Si1-xGex)2 using He-gas pressure”
by B Wolf, et al.
report:
The paper reports on new experimental data on the valence crossover in EuPd2(Si1-xGex)2 systems by measures of the magnetic susceptibility and thermal expansion at ambient and applied pressures. The paper is clearly written and the results are pertinent and deserves publication in the proceedings of the SCES conference. However, I strongly recommend to show a phase diagram indicating the thermal expansion and susceptibility data under pressure. Furthermore, I recommend to put the legend in fig. 3a) and fig. 3b).
We thank the Referee for reading the manuscript and for his/her comments and recommendations. As suggested by the referee, we added legends in fig. 3a and fig. 3b. In addition, we provide an inset in fig. 3b which displays a p-T phase diagram of EuPd2(Si1-xGex)2 and we modified the figure captions accordingly. Two sentences have been added at the beginning of the last paragraph on page 5 and at the end of page 5 where we refer to the new inset of figure 3b.
To facilitate the work by the Referee and the Editor, we provide, in addition to the revised version, a PDF version of the revised manuscript, where we indicate all the changes made. We believe that by addressing the points raised by the Referee the revised paper is now ready for publication.
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letter_editor-20102022-BW-ML.pdf