Abstract
Within a Kondo lattice, the strong hybridization between electrons localized in real space (r-space) and those delocalized in momentum-space (k-space) generates exotic electronic states called 'heavy fermions'. In URu2Si2 these effects begin at temperatures around 55 K but they are suddenly altered by an unidentified electronic phase transition at T-o=17.5 K. Whether this is conventional ordering of the k-space states, or a change in the hybridization of the r-space states at each U atom, is unknown. Here we use spectroscopic imaging scanning tunnelling microscopy (SI-STM) to image the evolution of URu2Si2 electronic structure simultaneously in r-space and k-space. Above T-o, the 'Fano lattice' electronic structure predicted for Kondo screening of a magnetic lattice is revealed. Below T-o, a partial energy gap without any associated density-wave signatures emerges from this Fano lattice. Heavy-quasiparticle interference imaging within this gap reveals its cause as the rapid splitting below T-o of a light k-space band into two new heavy fermion bands. Thus, the URu2Si2 'hidden order' state emerges directly from the Fano lattice electronic structure and exhibits characteristics, not of a conventional density wave, but of sudden alterations in both the hybridization at each U atom and the associated heavy fermion states.
Original language | English |
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Pages (from-to) | 570-576 |
Number of pages | 7 |
Journal | Nature |
Volume | 465 |
Issue number | 7298 |
DOIs | |
Publication status | Published - 3 Jun 2010 |
Keywords
- HEAVY-FERMION COMPOUNDS
- ELECTRON SUPERCONDUCTOR URU2SI2
- QUASI-PARTICLE INTERFERENCE
- POINT-CONTACT SPECTROSCOPY
- MAGNETIC EXCITATIONS
- SYSTEM URU2SI2
- BI2SR2CACU2O8+DELTA
- SURFACE
- STATE
- WAVE