  Magnetic dc susceptibility between 1.5 and 800 K, ac susceptibility and
magnetization, thermodynamic properties, temperature dependence of radio and
audio-wave dielectric constants and conductivity, contact-free dielectric
constants at mm-wavelengths, as well as ferroelectric polarization are reported
for single crystalline BiFeO3. A well developed anomaly in the magnetic
susceptibility signals the onset of antiferromagnetic order close to 635 K.
Beside this anomaly no further indications of phase or glass transitions are
indicated in the magnetic dc and ac susceptibilities down to the lowest
temperatures. The heat capacity has been measured from 2 K up to room
temperature and significant contributions from magnon excitations have been
detected. From the low-temperature heat capacity an anisotropy gap of the
magnon modes of the order of 6 meV has been determined. The dielectric
constants measured in standard two-point configuration are dominated by
Maxwell-Wagner like effects for temperatures T > 300 K and frequencies below 1
MHz. At lower temperatures the temperature dependence of the dielectric
constant and loss reveals no anomalies outside the experimental errors,
indicating neither phase transitions nor strong spin phonon coupling. The
temperature dependence of the dielectric constant was measured contact free at
microwave frequencies. At room temperature the dielectric constant has an
intrinsic value of 53. The loss is substantial and strongly frequency dependent
indicating the predominance of hopping conductivity. Finally, in small thin
samples we were able to measure the ferroelectric polarization between 10 and
200 K. The saturation polarization is of the order of 40 microC/cm^2,
comparable to reports in literature.
