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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
Preprint Link: scipost_202207_00023v2  (pdf)
Date accepted: 2023-04-25
Date submitted: 2022-11-04 09:14
Submitted by: Wolf, Bernd
Submitted to: SciPost Physics Proceedings
Proceedings issue: International Conference on Strongly Correlated Electron Systems (SCES2022)
Ontological classification
Academic field: Physics
  • Condensed Matter Physics - Experiment


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.

Author comments upon resubmission

---------------------------------------------------------------------- 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. ----------------------------------------------------------------------

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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). comments: 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 fig ure 3b.

List of changes

1.) added legends in fig. 3a and fig. 3b.
2.) provide an inset in fig. 3b.
3.) we modify the figure caption of fig.3
4.) added two sentences 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 fig ure 3b.

Published as SciPost Phys. Proc. 11, 022 (2023)

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Anonymous on 2022-12-06  [id 3105]

The paper has been changed concerning my first report and should be published in the present form.