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Visualizing the formation of the Kondo lattice and the hidden order in URu 2 Si 2

2010; National Academy of Sciences; Volume: 107; Issue: 23 Linguagem: Inglês

10.1073/pnas.1005892107

1091-6490

Pegor Aynajian, Eduardo H. da Silva Neto, Colin Parker, Y. K. Huang, Abhay N. Pasupathy, J. A. Mydosh, Ali Yazdani,

Physics of Superconductivity and Magnetism

Heavy electronic states originating from the f atomic orbitals underlie a rich variety of quantum phases of matter. We use atomic scale imaging and spectroscopy with the scanning tunneling microscope to examine the novel electronic states that emerge from the uranium f states in URu(2)Si(2). We find that, as the temperature is lowered, partial screening of the f electrons' spins gives rise to a spatially modulated Kondo-Fano resonance that is maximal between the surface U atoms. At T = 17.5 K, URu(2)Si(2) is known to undergo a second-order phase transition from the Kondo lattice state into a phase with a hidden order parameter. From tunneling spectroscopy, we identify a spatially modulated, bias-asymmetric energy gap with a mean-field temperature dependence that develops in the hidden order state. Spectroscopic imaging further reveals a spatial correlation between the hidden order gap and the Kondo resonance, suggesting that the two phenomena involve the same electronic states.