La substitution studies on the heavy-fermion superconductor CeRh${}_2$As${}_2$

Abstract

CeRh${}_2$As${}_2$ has been receiving considerable attention due to its unusual two-phase superconductivity. The superconducting (SC) phase appears at $T_{\mathrm{c}}$ = 0.35 K in an ordered state (phase I) of the Ce-4$f$ moments, which develops below $T_0$ = 0.55 K. The microscopic nature of phase I has not been fully established yet. We report a single-crystal study of the effect of La substitution on these low-temperature phases in Ce${}_{1-\text{x}}$La${}_{\text{x}}$Rh${}_2$As${}_2$ up to $x$ = 0.1. The lattice parameters increase monotonically with $x$, corresponding to an effective negative pressure of approximately -0.3 GPa for $x$ = 0.1. While the Ce${}^{3+}$ local valence state and the non-Fermi-liquid behavior are preserved, the resistivity coherence maximum $T_{\max }^{\ast }$ $\approx$ 45 K in the pristine sample shifts to lower temperatures with increasing $x$, indicating a suppression of the Kondo energy scale upon lattice expansion. On the other hand, both $T_{\mathrm{c}}$ and $T_0$ are rapidly suppressed to below 0.1 K for $x$ $>$ 0.05. Notably, such a rapid decrease of $T_{\mathrm{c}}$ under moderate negative pressure is unexpected, but is rather consistent with substitution-induced disorder effect which leads to strong pair breaking in unconventional superconductors. The observed fragility of phase I under both pressure and disorder may imply its itinerant origin.

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• Superconductivity and Local Inversion-Symmetry Breaking
• Possible quadrupole density wave in the superconducting Kondo lattice CeRh2As2
• Topological crystalline superconductivity in locally noncentrosymmetric CeRh${}_2$As${}_2$
• Observation of antiferromagnetic order as odd-parity multipoles inside the superconducting phase in CeRh${}_2$As${}_2$
• Non-symmorphic symmetry and field-driven odd-parity pairing in CeRh${}_2$As${}_2$
• Field-angle dependence reveals odd-parity superconductivity in CeRh${}_2$As${}_2$
• Two scenarios for superconductivity in CeRh${}_2$As${}_2$
• Parity transition of spin-singlet superconductivity using sub-lattice degrees of freedom
• Discovery of magnetic phase transitions in heavy-fermion superconductor CeRh${}_2$As${}_2$
• Decoupling multi-phase superconductivity from normal state ordering in CeRh${}_2$As${}_2$
• Coexistence of near-EF flat band and van Hove singularity in a two-phase superconductor
• Fermi Surface Nesting with Heavy Quasiparticles in the Locally Noncentrosymmetric Superconductor CeRh${}_2$As${}_2$
• Spectroscopic evidence of Kondo-induced quasi-quartet in CeRh${}_2$As${}_2$
• Correlation-induced Fermi surface evolution and topological crystalline superconductivity in CeRh2As2
• Exploring Fermi Surface Nesting and the Nature of Heavy Quasiparticles in the Spin-Triplet Superconductor Candidate CeRh${}_2$As${}_2$
• Conventional type-II superconductivity in locally non-centrosymmetric LaRh${}_2$As${}_2$ single crystals
• Pressure-tuned quantum criticality in the locally non-centrosymmetric superconductor CeRh${}_2$As${}_2$
• Coexistence of local magnetism and superconductivity in the heavy-fermion CeRh${}_2$As${}_2$ revealed by $\mu$SR studies
• Tuning the parity of superconductivity in CeRh2As2 via pressure
• Kramers' degenerate magnetism and superconductivity
• Exposing the odd-parity superconductivity in CeRh${}_2$As${}_2$ with hydrostatic pressure
• Anisotropic magnetic and quadrupolar H-T phase diagram of CeRh2As2
• Origin of the non-Fermi-liquid behavior in CeRh2As2
• Unified picture of superconductivity and magnetism in CeRh${}_2$As${}_2$
• The phase diagram of CeRh${}_2$As${}_2$ for out-of-plane magnetic field
• Disorder-induced suppression of superconductivity in infinite-layer nickelates
• Thermodynamics, elastic anomalies and excitations in the field induced phases of CeRh2As2