Structural and Magnetic Properties of ${\rm FeTiTaO}_{6}$

We have investigated the structural and magnetic properties of
${\rm FeTiTaO}_{6}$
. From the Rietveld-refined XRD patterns of
${\rm FeTiTaO}_{6}$
, its crystal structure at room temperature is determined to be the rutile structure with lattice constants of
$a_{0}=4.65\ \hbox{\rm{\AA}}$
, and
$c_{0}=3.02\ \hbox{\rm{\AA}}$
. The c/a ratio of 0.649 is almost same as the value in the parent rutile
${\rm TiO}_{2}$
, which is 0.644. Based on the temperature dependence of the susceptibility between 3 and 400 K, measured with superconducting quantum interference device (SQUID), the magnetic Néel temperature
$(T_{N})$
, which is defined as temperature of the maximum slope in
$dM/dT$
, is determined to be 40 K. The detailed studies of the local structure have been carried out with
$^{57}{\rm Co}$
Mössbauer spectroscopy at various temperatures. The Mössbauer spectra of
${\rm FeTiTaO}_{6}$
were composed of two six-line hyperfine patterns below 40 K. Also, the magnetic hyperfine field of
${\rm FeTiTaO}_{6}$
is found to be 472 kOe at 4.2 K. The Mössbauer spectra clearly reveal the presence of the magnetic ordering below 40 K in
${\rm FeTiTaO}_{6}$
.