Visualizing the formation of the Kondo lattice and the hidden order in URu2Si2

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 23; pp. 10383 - 10388
• Main Authors: Aynajian, Pegor, da Silva Neto, Eduardo H., Parker, Colin V., Huang, Yingkai, Pasupathy, Abhay, Mydosh, John, Yazdani, Ali
• Format: Journal Article
• Language: English
• Published: National Acad Sciences 08.06.2010; National Academy of Sciences
• Subjects: Physical Sciences
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1005892107

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.