Europhys. Lett., 63 (6) , pp. 860-866 (2003)
Field tuning of the electron and hole populations in the ruthenateWei-Li Lee1, M. K. Haas2, G. Lawes3, A. P. Ramirez3, R. J. Cava2, 4 and N. P. Ong1, 4
1 Department of Physics, Princeton University - Princeton, NJ 08544, USA
2 Department of Chemistry, Princeton University - Princeton, NJ 08544, USA
3 Los Alamos National Laboratory - Los Alamos, NM 87544, USA
4 Princeton Materials Institute, Princeton University - Princeton, NJ 08544, USA
(Received 15 May 2003; accepted in final form 4 July 2003)
Experiments on the Hall coefficient and heat capacity C reveal an unusual, compensated electronic ground state in the ruthenate . At low temperature T, decreases linearly with magnetic field |H| for fields larger than the field scale set by the Zeeman energy. The results suggest that the electron and hole populations are tuned by H in opposite directions via coupling of the spins to the field. As T is decreased below 5 , the curve C(T)/T vs. T2 shows an anomalous flattening consistent with a rapidly growing Sommerfeld parameter . We discuss shifts of the electron and hole chemical potentials by H to interpret the observed behavior of .
72.15.-v - Electronic conduction in metals and alloys.
72.60.+g - Mixed conductivity and conductivity transitions.
71.27.+a - Strongly correlated electron systems; heavy fermions.
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