Field-Tuning of the electron and hole populations in the ruthenate Bi_3Ru_3O_11

TL;DR

This study investigates the unusual electronic ground state of Bi_3Ru_3O_11, revealing field-tuned electron and hole populations and anomalous low-temperature behavior through Hall coefficient and heat capacity measurements.

Contribution

It demonstrates how magnetic field influences electron and hole populations in Bi_3Ru_3O_11, providing new insights into its compensated electronic state and low-temperature properties.

Findings

Hall coefficient decreases linearly with magnetic field at low T

Heat capacity shows anomalous flattening below 5 K

Electron and hole chemical potentials shift with magnetic field

Abstract

Experiments on the Hall coefficient R_H and heat capactity C reveal an unusual, compensated electronic ground state in the ruthenate Bi_3Ru_3O_11. At low temperature T, R_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 K, the curve C(T)/T vs. T^2 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_H.