1202.2753 (Y. Machida et al.)

Thermoelectric response near a quantum critical point of beta-YbAlB4 and
YbRh2Si2: A comparative study    [PDF]

Y. Machida, K. Tomokuni, C. Ogura, K. Izawa, K. Kuga, S. Nakatsuji, G. Lapertot, G. Knebel, J. -P. Brison, J. Flouquet

The thermoelectric coefficients have been measured on the Yb-based heavy
fermion compounds beta-YbAlB4 and YbRh2Si2 down to a very low temperature. We
observe a striking difference in the behavior of the Seebeck coefficient, S in
the vicinity of the Quantum Critical Point (QCP) in the two systems. As the
critical field is approached, S/T enhances in beta-YbAlB4 but is drastically
reduced in YbRh2Si2. While in the former system, the ratio of
thermopower-to-specific heat remains constant, it drastically drops near the
QCP in YbRh2Si2. In both systems, on the other hand, the Nernst coefficient
shows a diverging behavior near the QCP. The results provide a new window to
the way various energy scales of the system behave and eventually vanish near a
QCP.

View original: http://arxiv.org/abs/1202.2753