Transport Properties and Electronic States in the Layered Thermoelectric Rhodate (Bi1-xPbx)1.8Ba2Rh1.9Oy

Resistivity, thermopower and Hall coefficient have been systematically measured for polycrystalline samples of (Bi 1- x Pb x ) 1.8 Ba 2 Rh 1.9 O y . An upturn of the resistivity and the Hall coefficient below 50 K is ascribed to decrease in the density of states due to a pseudogap formation. The thermopower and Hall coefficient are nearly identical to those of the thermoelectric oxide Bi 2 Sr 2 Co 2 O y . This suggests a nearly identical density of states between the two oxides, which is also verified from a first-principle calculation, where a broader 4d orbital and a larger rhodium-rhodium distance along the in-plane direction accidentally give nearly the same density of states as those of the layered cobalt oxides.