Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ${\mathrm{ZrAs}}_{1.58}{\mathrm{Se}}_{0.39}$

Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ${ZrAs}_{1.58} {Se}_{0.39}$

T. Cichorek, L. Bochenek, M. Schmidt, A. Czulucki, G. Auffermann, R. Kniep, R. Niewa, F. Steglich, and S. Kirchner

Phys. Rev. Lett. 117, 106601 – Published 1 September 2016

Abstract

We address the origin of the magnetic-field-independent $- | A | T^{1 / 2}$ term observed in the low-temperature resistivity of several As-based metallic systems of the PbFCl structure type. For the layered compound ${ZrAs}_{1.58} {Se}_{0.39}$ , we show that vacancies in the square nets of As give rise to the low-temperature transport anomaly over a wide temperature regime of almost two decades in temperature. This low-temperature behavior is in line with the nonmagnetic version of the two-channel Kondo effect, whose origin we ascribe to a dynamic Jahn-Teller effect operating at the vacancy-carrying As layer with a $C_{4}$ symmetry. The pair-breaking nature of the dynamical defects in the square nets of As explains the low superconducting transition temperature $T_{c} \approx 0.14 K$ of ${ZrAs}_{1.58} {Se}_{0.39}$ compared to the free-of-vacancies homologue ${ZrP}_{1.54} S_{0.46}$ ( $T_{c} \approx 3.7 K$ ). Our findings should be relevant to a wide class of metals with disordered pnictogen layers.

Received 21 November 2015

DOI:https://doi.org/10.1103/PhysRevLett.117.106601

Physics Subject Headings (PhySH)

Kondo effect Vacancies

Pnictides

Transport techniques

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

T. Cichorek and L. Bochenek

Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wroclaw, Poland

M. Schmidt, A. Czulucki, G. Auffermann, and R. Kniep

Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany

R. Niewa

Institute of Inorganic Chemistry, University of Stuttgart, 70569 Stuttgart, Germany

F. Steglich

Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany, Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang 310058, China, and Institute of Physics, Chinese Academy of Science, Beijing 100190, China

S. Kirchner^*

Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang 310058, China

^*stefan.kirchner@correlated-matter.com

Comments & Replies

Comment on “Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ${ZrAs}_{1.58} {Se}_{0.39}$ ”

Daniel Gnida

Phys. Rev. Lett. 118, 259701 (2017)

Cichorek et al. Reply:

T. Cichorek, L. Bochenek, M. Schmidt, R. Niewa, A. Czulucki, G. Auffermann, F. Steglich, R. Kniep, and S. Kirchner

Phys. Rev. Lett. 118, 259702 (2017)

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Vol. 117, Iss. 10 — 2 September 2016

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Figure 1
Structural disorder in zirconium pnictide chalcogenides. (a) The PbFCl structure type with the fully occupied $Q (2 c)$ site (green) by Ch together with Pn. The $Pn (2 a)$ site (blue) arranged within planar layers is only occupied to 97% by As in ${ZrAs}_{1.58} {Se}_{0.39}$ , but it is fully occupied by P in ${ZrP}_{1.54} S_{0.46}$ . (b) The vacancies in ${ZrAs}_{1.58} {Se}_{0.39}$ (left panel) manifest random displacements of As within the layer due to homoatomic covalent bond formation. This is indicated by flattened displacement ellipsoids in the structure refinements, while the refined displacement ellipsoids in ${ZrP}_{1.54} S_{0.46}$ (right panel) are nearly spherical.
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Figure 2
Characteristics of the pnictide chalcogenide superconductors ${ZrAs}_{1.58} {Se}_{0.39}$ and ${ZrP}_{1.54} S_{0.46}$ . (a) Normal-state electrical resistivity along the $c$ axis of ${ZrAs}_{1.58} {Se}_{0.39}$ and ${ZrP}_{1.54} S_{0.46}$ (the two specimens of the former material were cut off from the same single crystal). (b) The same results, but with a focus on the vicinity of the superconducting transition, as $ρ / ρ_{0}$ vs $T / T_{c}^{onset}$ . For clarity, the temperature scale of the $ρ (T)$ data for the P-based system was multiplied by a factor of 5. (c) Low-temperature specific heat for ${ZrAs}_{1.58} {Se}_{0.39}$ and ${ZrP}_{1.54} S_{0.46}$ . (Inset) Electronic specific heat of ${ZrP}_{1.54} S_{0.46}$ in the vicinity of the superconducting phase transition, as $C_{e} / T$ vs temperature. $C_{e} = C - C_{ph}$ , where $C_{ph}$ is the phonon contribution, estimated from the normal-state $B = 0.5 T$ data. (d) Zero-field-cooled (ZFC) and field-cooled (FC) dc magnetic susceptibility as a function of temperature for ${ZrP}_{1.54} S_{0.46}$ . (Inset) Evidence for large shielding in ${ZrAs}_{1.58} {Se}_{0.39}$ is provided by the sizable diamagnetic signal of the ac magnetic susceptibility below about $T = 0.125 K$ .
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Figure 3
Evidence for the 2CK effect due to As vacancies. (a) Despite very similar basic low-temperature properties of ${ZrAs}_{1.58} {Se}_{0.39}$ and ${ZrP}_{1.54} S_{0.46}$ , these sister compounds display qualitatively different responses of $(ρ - ρ_{\min}) / ρ_{\min}$ vs $T^{1 / 2}$ . Note the magnetic-field-independent $- | A | T^{1 / 2}$ contribution to $ρ (T)$ for ${ZrAs}_{1.58} {Se}_{0.39}$ , i.e., for a system with vacancies in the pnictogen layer. (Inset) Low- $T$ resistivity of ${ZrP}_{1.54} S_{0.46}$ measured in zero and varying magnetic fields up to 14 T. For $B = 0$ , $ρ_{\min} = ρ (9 K)$ was taken. (b) Remarkable differences of the $B$ -independent low- $T$ $ρ (T)$ as $(ρ - ρ_{\min}) / ρ_{\min}$ vs $T^{1 / 2}$ for two single-crystalline ${ZrAs}_{1.58} {Se}_{0.39}$ specimens with similar residual resistivities. The dashed line shows the magnitude of a hypothetical $- | A | T^{1 / 2}$ correction to $ρ (T)$ for sample 2 due to a 3D EEI assuming that ${\tilde{F}}_{σ} = 0$ . (Inset) Magnetic-field dependence of $ρ (T)$ of ${ZrAs}_{1.58} {Se}_{0.39}$ and ${ZrP}_{1.54} S_{0.46}$ single crystals. Note that the data for ${ZrAs}_{1.58} {Se}_{0.39}$ are divided by a factor of 10. (c)–(f) Dynamic structural scattering centers in metallic arsenide selenides. Shown are different possible arrangements of dimers or oligomers within the As layer triggered by the vacancy (the red square). Arsenic atoms may, for example, arrange as dimers, trimers, oligomers of several As atoms, or infinite chains with a zigzag or sawtooth configuration. (f) is obtained from (e) by a $π / 2$ rotation of the arrangement of (e), indicating how the $C_{4}$ symmetry is dynamically restored.
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Physical Review Letters

Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ZrAs1.58Se0.39

T. Cichorek, L. Bochenek, M. Schmidt, A. Czulucki, G. Auffermann, R. Kniep, R. Niewa, F. Steglich, and S. Kirchner

Phys. Rev. Lett. 117, 106601 – Published 1 September 2016

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Comments & Replies

Comment on “Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ZrAs1.58Se0.39”

Daniel Gnida

Phys. Rev. Lett. 118, 259701 (2017)

Cichorek et al. Reply:

T. Cichorek, L. Bochenek, M. Schmidt, R. Niewa, A. Czulucki, G. Auffermann, F. Steglich, R. Kniep, and S. Kirchner

Phys. Rev. Lett. 118, 259702 (2017)

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Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ${ZrAs}_{1.58} {Se}_{0.39}$

Comment on “Two-Channel Kondo Physics due to As Vacancies in the Layered Compound ${ZrAs}_{1.58} {Se}_{0.39}$ ”