Magnetoresistance and magnetothermopower in the rhodium misfit oxide [ Bi 1.95 Ba 1.95 Rh 0.1 O 4 ] [ Rh O 2 ] 1.8

摘要: The magnetotransport properties of the Rh-based $[{\mathrm{Bi}}_{1.95}{\mathrm{Ba}}_{1.95}{\mathrm{Rh}}_{0.1}{\mathrm{O}}_{4}]{[\mathrm{Rh}{\mathrm{O}}_{2}]}_{1.8}$ misfit oxide have been investigated. A metallic behavior is observed, coexisting with a large thermopower $S$ $+95\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{V}∕\mathrm{K}$ at room temperature, similar to what observed in cobalt based oxides. This value can be explained by coexistence ${\mathrm{Rh}}^{3+}(4{d}^{6})$ and ${\mathrm{Rh}}^{4+}(4{d}^{5})$ $\mathrm{Rh}{\mathrm{O}}_{2}$ layers, suggesting that they same influence as isoelectronic low spin state ${t}_{2g}^{6}$ $S=0$ ${\mathrm{Co}}^{3+}$ $(3{d}^{6})$ ${t}_{2g}^{5}$ $S=1∕2$ ${\mathrm{Co}}^{4+}$ $(3{d}^{5})$ From specific heat measurements, coefficient $\ensuremath{\gamma}=38\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}\phantom{\rule{0.2em}{0ex}}\mathrm{mol}{(\mathrm{Rh})}^{\ensuremath{-}1}$ shows electron correlations are moderately strong. small magnetoresistance $T$, two contributions, first negative up $7\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, positive for ${\ensuremath{\mu}}_{0}Hg7\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, reaching $+5%$ $14\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ $T=2.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. unique example rhodium oxides, emphasizing peculiarity transport arising from these $\mathrm{Cd}{\mathrm{I}}_{2}$ type layers. depends also strongly on field, magnetothermopower $\ensuremath{-}50%$ $9\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ $2.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.