Critical point anomalies in doped ${\mathrm{CeRhIn}}_{5}$

Critical point anomalies in doped ${CeRhIn}_{5}$

R. Mathew Roy, S. Pal, R. Yang, S. Roh, S. Shin, T. B. Park, T. Park, and M. Dressel

Phys. Rev. B 109, 075149 – Published 22 February 2024

Abstract

The heavy-fermion compound ${CeRhIn}_{5}$ can be tuned through a quantum critical point, when In is partially replaced by Sn. In this way additional charge carriers are introduced and the antiferromagnetic order is gradually suppressed to zero temperature. Here we investigate the temperature-dependent optical properties of $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ single crystals for $x = 4.4 %$ , 6.9%, and 9.8%. With increasing Sn concentration the infrared conductivity reveals a clear enhancement of the $c − f$ hybridization strength. At low temperatures we observe a non-Fermi-liquid behavior in the frequency dependence of the scattering rate and effective mass up to approximately 50 meV in all three compounds. In addition, below a characteristic temperature $T^{*} \approx 10$ K, the temperature-dependent resistivity $ρ (T)$ follows a $log T$ behavior, typical for a non-Fermi-liquid. The temperature-dependent magnetization also exhibits anomalous behavior below $T^{*}$ . Our investigation reveal that below $T^{*}$ the system shows a pronounced non-Fermi-liquid behavior and $T^{*}$ monotonically increases as the quantum critical point is approached.

Received 11 October 2023
Revised 10 January 2024
Accepted 7 February 2024

DOI:https://doi.org/10.1103/PhysRevB.109.075149

Physics Subject Headings (PhySH)

Electrical conductivity Fermions Kondo effect Magnetic susceptibility Optical conductivity Quantum phase transitions

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

R. Mathew Roy ¹, S. Pal ¹, R. Yang¹, S. Roh¹, S. Shin², T. B. Park³, T. Park ³, and M. Dressel ¹

¹1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
²Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
³Centre for Quantum Materials and Superconductivity (CQMS), Sungkyunkwan University, Suon 16419, Republic of Korea

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Vol. 109, Iss. 7 — 15 February 2024

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Figure 1
The temperature-dependent reflectivity of $CeRh {({Sn}_{1 - x} {In}_{x})}_{5}$ with Sn concentrations of $x = 4.4 %$ , 6.9%, and 9.8%, respectively. The inset shows the low-frequency reflectivity for $T = 10$ K and 300 K on a logarithmic scale; the Hagen-Rubens extrapolation below 80 ${cm}^{- 1}$ is indicated by dashed lines.
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Figure 2
Real part of the optical conductivity of $CeRh {({Sn}_{1 - x} {In}_{x})}_{5}$ obtained from reflectivity measurements at different temperatures, with Sn concentrations of $x = 4.4 %$ , 6.9%, and 9.8%, respectively. Note the different ordinates. The insets demonstrate how the 10 K spectra can be modeled by Drude and Lorentz terms. The MIR feature that characterizes the formation of heavy fermions develops below 30 K, which gets more prominently broadened toward 9.8% Sn concentration.
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Figure 3
Comparison of the low-temperature conductivity of $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ with $x = 4.4 %$ , 6.9%, and 9.8%. The arrows illustrate the evolution of $E_{MIR}$ with increasing Sn concentration indicating an enhancement of $c − f$ hybridization strength. The inset presents the transfer of spectral weight from the Drude to the Lorentz component with increasing Sn concentration.
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Figure 4
(a) The frequency-dependent scattering rate $Γ (ω)$ of $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ reveals a linear $ω$ dependence indicating a non-Fermi-liquid behavior. The dotted lines represent $Γ \propto ω$ for the three compositions. (b) The corresponding frequency-dependent effective mass $m^{*} (ω)$ diverges at low frequencies.
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Figure 5
(a) Normalized resistivity for three compounds indicating a drop in resistivity with the formation of Kondo lattice and a sharp drop around the coherent temperature $T_{coh}$ . (b)–(d) Low-temperature resistivity of $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ . The left and lower axes use logarithmic scales. The upper and right axes correspond to a $ρ (T)$ vs $T^{2}$ representation. The arrows indicate the lower-temperature limit of the Fermi liquid behavior, where $ρ (T) \propto T^{2}$ is observed.
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Figure 6
(a) Magnetic susceptibility as a function of temperature for different Sn concentrations in $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ . With increasing $x$ the susceptibility drops in magnitude and a saturation is observed as heavy-fermion quasiparticles form. The inset shows a rise in susceptibility for Sn $6.9 %$ and Sn $9.8 %$ . (b)–(d) Temperature-dependent susceptibility of $CeRh {({In}_{1 - x} {Sn}_{x})}_{5}$ with $x = 4.4 %$ , 6.9%, and 9.8%. No clear saturation is found at low temperatures. For 4.4% of Sn an antiferromagnetic transition is seen at 2 K. An anomaly-like hump broadens and shifts to higher temperature with increasing Sn concentration.
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Physical Review B

covering condensed matter and materials physics

Critical point anomalies in doped ${CeRhIn}_{5}$

R. Mathew Roy, S. Pal, R. Yang, S. Roh, S. Shin, T. B. Park, T. Park, and M. Dressel

Phys. Rev. B 109, 075149 – Published 22 February 2024

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Physical Review B

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Critical point anomalies in doped CeRhIn5

R. Mathew Roy, S. Pal, R. Yang, S. Roh, S. Shin, T. B. Park, T. Park, and M. Dressel

Phys. Rev. B 109, 075149 – Published 22 February 2024

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Critical point anomalies in doped ${CeRhIn}_{5}$