Abstract
We have investigated the structural and magnetic phase transitions in with synchrotron powder x-ray diffraction, resonant ultrasound spectroscopy, and magnetization measurements. Upon Nb doping, the structural transition shifts to higher temperatures and the room temperature lattice parameter increases while the magnitude of the octahedral tilting decreases. In addition, Nb substitution for Ti destabilizes the antiferromagnetic ground state of the parent compound and long-range ferromagnetic order is observed in the samples with . The structural transition in pure and doped compounds is marked by a dramatic steplike softening of the elastic moduli near , which resembles that of and can be adequately modeled using the Landau free energy model employing the same coupling between strain and octahedral tilting order parameter as previously used to model .
1 More- Received 20 May 2015
DOI:https://doi.org/10.1103/PhysRevB.92.024109
©2015 American Physical Society