  Ferromagnetic metallic oxides have potential applications in spincaloric
devices which utilize the spin property of charge carriers for interconversion
of heat and electricity through the spin Seebeck or the anomalous Nernst effect
or both. In this work, we synthesized polycrystalline La0.5S0.5CoO3 by
microwave irradiation method and studied its transverse thermoelectric voltage
(Nernst thermopower) and change in the linear dimension of the sample (Joule
magnetostriction) in response to external magnetic fields. In addition,
magnetization, temperature dependences of electrical resistivity, and
longitudinal Seebeck coefficient (Sxx) in absence of an external magnetic field
were also measured. The sample is ferromagnetic with a Curie temperature of TC
= 247 K and shows a metal-like resistivity above and below TC with a negative
sign of Sxx suggesting charge transport due to electrons. Magnetic field
dependence of the Nernst thermopower (Sxy) at a fixed temperature shows a rapid
increase at low fields and a tendency to saturate at high fields as like the
magnetization. Anomalous contribution to Sxy was extracted from total Sxy
measured and it exhibits a maximum value of ~ 0.21 microV/K at 180 K for H = 50
kOe, which is comparable to the value found in a single crystal for a lower Sr
content. The Joule magnetostriction is positive, i.e., the length of the sample
expands along the direction of the magnetic field and it does not saturate even
at 50 kOe. The magnetostriction increases with decreasing temperature below TC
and reaches a maximum value of 500 ppm at T = 40 K and below. Coexistence of
the anomalous Nernst thermopower and giant magnetostriction in a single
compound has potential applications for thermal energy harvesting and
low-temperature actuators, respectively.
