Field tuning of the electron and hole populations in the ruthenate $\chem{Bi_3Ru_3O_{11}}$

Wei-Li Lee; M. K. Haas; G. Lawes; A. P. Ramirez; R. J. Cava; N. P. Ong

doi:doi:10.1209/epl/i2003-00599-0

DOI: 10.1209/epl/i2003-00599-0
Europhys. Lett., 63 (6) , pp. 860-866 (2003)

Field tuning of the electron and hole populations in the ruthenate $\chem{Bi_3Ru_3O_{11}}$

Wei-Li Lee¹, M. K. Haas², G. Lawes³, A. P. Ramirez³, R. J. Cava^{2, 4} and N. P. Ong^{1, 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)

Abstract
Experiments on the Hall coefficient $R_{\ab{H}}$ and heat capacity C reveal an unusual, compensated electronic ground state in the ruthenate $\chem{Bi_3Ru_3O_{11}}$ . At low temperature T, $R_{\ab{H}}$ 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 $\un{K}$ , the curve C(T)/T vs. T² shows an anomalous flattening consistent with a rapidly growing Sommerfeld parameter $\gamma(T)$ . We discuss shifts of the electron and hole chemical potentials by H to interpret the observed behavior of $R_{\ab{H}}$ .

PACS
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.

© EDP Sciences 2003