Skew scattering dominated anomalous Nernst effect in monovalent cation doped bulk La1-xNaxMnO3

We report the anomalous Nernst effect (ANE), i.e. creation of electrical voltage transverse to the direction of applied temperature gradient and magnetic field in bulk samples of La1-xNaxMnO3 (x = 0.02, 0.05, 0.1 and 0.3) whose ferromagnetic Cure temperature(TC) varies from 251 K for x = 0.02 to 310 K for x = 0.3. We measured both the magnetic field and temperature dependences of ANE. While ANE is negligible much above TC, it increases rapidly at TC and exhibits a peak just below it. The field dependence of ANE closely follows magnetization. The maximum value of ANE at TC increases from x = 0.02 to 0.1, but decreases significantly for x = 0.3. Besides ANE, we also measured dc resistivity and longitudinal Seebeck coefficient as a function of temperature and used these data to analyze our results. Our data analysis indicates that skew scattering is the main source of the ANE in these oxides.