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arXiv · 1711.05151

Evolution of the Kondo lattice and non-Fermi liquid excitations in a heavy-fermion metal

S. Seiro·L. Jiao·S. Kirchner·S. Hartmann·S. Friedemann·C. Krellner·C. Geibel·Q. Si·F. Steglich·S. Wirth
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Abstract

Strong electron correlations can give rise to extraordinary properties of metals with renormalized quasiparticles which are at the basis of Landau's Fermi liquid theory. Near a quantum critical point, these quasiparticles can be destroyed and non-Fermi liquid behavior ensues. YbRh$_2$Si$_2$ is a prototypical correlated metal as it exhibits quasiparticles formation, formation of Kondo lattice coherence and quasiparticle destruction at a field-induced quantum critical point. Here we show how, upon lowering the temperature, the Kondo lattice coherence develops and finally gives way to non-Fermi liquid electronic excitations. By measuring the single-particle excitations through scanning tunneling spectroscopy down to 0.3 K, we find the Kondo lattice peak emerging below the Kondo temperature $T_{\rm K} \sim$ 25 K, yet this peak displays a non-trivial temperature dependence with a strong increase around 3.3 K. At the lowest temperature and as a function of an external magnetic field, the width of this peak is minimized in the quantum critical regime. Our results provide a striking demonstration of the non-Fermi liquid electronic excitations in quantum critical metals, thereby elucidating the strange-metal phenomena that have been ubiquitously observed in strongly correlated electron materials.

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S. Seiro, L. Jiao, S. Kirchner, S. Hartmann, S. Friedemann, C. Krellner, C. Geibel, Q. Si, F. Steglich, S. Wirth. 2017-11-16. Evolution of the Kondo lattice and non-Fermi liquid excitations in a heavy-fermion metal. https://doi.org/10.1038/s41467-018-05801-5

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