||Anomalous Thermoelectric Response in an Orbital-Ordered Oxide Near and Far from Equilibrium
Nishina, Yasuo ,
Okazaki, Ryuji ,
Yasu, Yukio ,
Nakamura, FumihikoTerasaki, Ichiro
Journal of the Physical Society of Japan
093707 , 2017-09-15 , 日本物理学会
We report the thermoelectric transport properties in the orbital-ordered Mott insulating phase of Ca2RuO4 close to and far from equilibrium. Near equilibrium conditions where the temperature gradient is only applied to the sample, an insulating but non-monotonic temperature variation of the Seebeck coefficient is observed, which is accounted for in terms of a temperature-induced suppression of the orbital order. In non-equilibrium conditions where we have applied high electrical currents, we find that the Seebeck coefficient is anomalously increased in magnitude with increasing external current. The present result clearly demonstrates a non-thermal effect since the heating simply causes a decrease of the Seebeck coefficient, implying a non-trivial non-equilibrium effect such as a modification of the spin and orbital state in currents.