Abstract
The thermoelectric coefficients have been measured down to a very low temperature for the Yb-based heavy-fermion compounds and , often considered as model systems for the local quantum criticality case. We observe a striking difference in the behavior of the Seebeck coefficient in the vicinity of their respective quantum critical point (QCP). Approaching the critical field, is enhanced in , but drastically reduced in . The ratio of thermopower to specific heat remains constant for , but it is significantly reduced near the QCP in . In both systems, on the other hand, the Nernst coefficient shows a diverging behavior near the QCP. The interplay between valence and magnetic quantum criticality and the additional possibility of a Lifshitz transition crossing the critical field under magnetic field are discussed as the origin of the different behaviors of these compounds.
- Received 13 February 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.156405
© 2012 American Physical Society