Thermoelectric Properties of Fe0.2Co3.8Sb12-xTex ... - Physics

Freezing of the octahedral tilt near ferromagnetic transition and appearance of a glassy
phase at low temperature driven by the tilt instabilities in SrRuO 3
Chanchal Sow
Department of Physics, Indian Institute of Science, Bangalore 560012, India
SrRuO 3 is a well known itinerant ferromagnet with many intriguing characteristics. Here we
present a critical investigation on the structural, magnetic, and magnetotransport properties of
polycrystalline SrRu (1-x) O 3 (0.07 < x < 0) samples with uniquely defined ferromagnetic transition
temperatures. The ac magnetic susceptibility study exhibits the remarkable memory effect, a
distinct characteristic of glassy behavior, at low temperatures. The transport study suggests a
crossover from Fermi-liquid to non-Fermi-liquid behavior. Most strikingly, the temperaturedependent
magnetoresistance reveals the possibility for an additional magnetic ordering (apart
from ferromagnetic) by demonstrating a peak in magnetoresistance at the low temperature side
as well. In addition, the temperature-dependent coercive field shows a plateau around 50 K. In
order to understand the genesis of such unusual low-temperature magnetic features, we have
undertaken a detailed temperature dependent (5-250 K) neutron diffraction study. We observe a
freezing of the octahedral tilt near the ferromagnetic transition and unusual changes in the
structural parameters (unit-cell lattice parameters, octahedral tilt etc.) near the onset of low
temperature spin glass like phase. A reduction of the ordered magnetic moment and a decline in
the total integrated magnetic intensity is also observed around the same temperature. Hence it is
believed that the low-temperature anomalous magnetic response is closely intertwined to the
lattice-parameter change.
Reference:
[1] C. Sow, D. Samal, P. S. A. Kumar, A. K. Bera, and S. M. Yusuf, Phys. Rev. B 85, 224426
(2012).
[2] C. Sow, D. Samal, and P. S. A. Kumar, J. Appl. Phys. 111, 07E121 (2012).