- Mo, S-K;
- Lee, WS;
- Schmitt, F;
- Chen, YL;
- Lu, DH;
- Capan, C;
- Kim, DJ;
- Fisk, Z;
- Zhang, C-Q;
- Hussain, Z;
- Shen, Z-X
We present ultrahigh resolution angle-resolved photoemission data of the prototypical Kondo lattice system YbRh 2Si 2, using a 7 eV laser photon source. Detailed temperature dependent measurements reveal the development of coherent states, in the form of sharp, weakly dispersing peaks at the lowest energy of single-electron spectra, below a characteristic temperature. The characteristic temperature, obtained from angle-resolved photoemission, is intriguingly of exactly the same scale as the energy and the lifetime of the coherent state. © 2012 American Physical Society.