Charge density wave fluctuations, heavy electrons, and superconductivity in KNi${}_2$S${}_2$

Abstract

Understanding the complexities of electronic and magnetic ground states in solids is one of the main goals of solid-state physics. Materials with the canonical ThCr${}_2$Si${}_2$-type structure have proved particularly fruitful in this regards, as they exhibit a wide range of technologically advantageous physical properties described by "many-body physics," including high-temperature superconductivity and heavy fermion behavior. Here, using high-resolution synchrotron X-ray diffraction and time-of-flight neutron scattering, we show that the isostructural mixed valence compound, KNi${}_2$S${}_2$, displays a number of highly unusual structural transitions, most notably the presence of charge density wave fluctuations that disappear on cooling. This behavior occurs without magnetic or charge order, in contrast to expectations based on all other known materials. Furthermore, the low-temperature electronic state of KNi${}_2$S${}_2$ is found to exhibit many characteristics of heavy-fermion behavior, including a heavy electron state ($m^{\ast }/m_e\sim$ 24), with a negative coefficient of thermal expansion, and superconductivity below $T_c$ = 0.46(2) K. In the potassium nickel sulfide, these behaviors arise in the absence of localized magnetism, and instead appear to originate in proximity to charge order.

10 pages, 14 Figures

References in corpus (18)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• Evidence for an electron nematic phase transition in underdoped iron pnictide superconductors
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Reemerging superconductivity at 48 K across quantum criticality in iron chalcogenides
• Multiband magnetism and superconductivity in Fe-based compounds
• Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3
• Valley density-wave and multiband superconductivity in Fe-pnictides
• Orbital Selective Magnetism in the Spin-Ladder Iron Selenides Ba${}_{1-x}$K${}_x$Fe${}_2$Se${}_3$
• Mixed-Valence-Driven Heavy-Fermion Behavior and Superconductivity in KNi${}_2$Se${}_2$
• Metal-Insulator Transition and Orbital Order in PbRuO3
• Type I Superconductivity in YbSb2 Single Crystals
• Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions
• Sleuthing Hidden Order
• Stoichiometry, Spin Fluctuations, and Superconductivity in LaNiPO
• Structural Phase Transitions in SrRh2As2
• Anisotropic magnetoelastic coupling in single-crystalline CeFeAsO as seen via high-resolution x-ray diffraction

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• Correlated local dipoles in PbTe
• Multiband Superconductivity of Heavy Electrons in TlNi2Se2 single crystal
• Multi-gap nodeless superconductivity in nickel chalcogenide TlNi2Se2
• Superconductivity in a new layered nickel-selenide CsNi2Se2
• Anomalous Dome-like Superconductivity in RE2(Cu1-xNix)5As3O2(RE=La, Pr, Nd)
• Correlation effects in the electronic structure of the Ni-based superconducting KNi2S2
• Anomalous Pressure Dependence of the Superconducting Transition Temperature in TlNi${}_2$Se${}_{2-x}$S${}_x$
• Theory of Charge Order and Heavy-Electron Formation in the Mixed-Valence Compound KNi${}_2$Se${}_2$
• Optical properties of TlNi2Se2: Observation of pseudogap formation
• A Single-Crystal Neutron Diffraction Study on Magnetic Structure of CsCo2Se2
• Trends in structural, electronic properties, Fermi surface topology, and inter-atomic bonding in the series of ternary layered dichalcogenides KNi2S2, KNi2Se2, and KNi2Te2 from first principles calculations
• Representational Analysis of Extended Disorder in Atomistic Ensembles Derived from Total Scattering Data