Anomalous Hall Effect in AgSbTe2

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Abstract
The Hall coefficient of the ternary semiconductor AgSbTe2 near room temperature is positive in some specimens and negative in others, although the Seebeck coefficient is always positive. The negative Hall coefficient decreases as the temperature is lowered from 180°K to 70°K and changes sign in lower temperatures. This negative Hall coefficient is associated with the presence in the AgSbTe2 of a second phase consisting of Ag2Te. The properties of the two‐phase material are interpreted in terms of the theory of the transport properties of inhomogeneous semiconductors. In single‐phase AgSbTe2 containing 3×1019 holes per cm3, the hole mobility is 35 cm2/v sec at 300°K and it varies approximately as T−0.5. {Note added in proof. It has been suggested by Armstrong, Faust, and Tiller [J. Appl. Phys. 31, 1954 (1960)] that the pattern in Fig. 3(a) is associated with the presence of Sb2Te3 as a Widmanstätten precipitate along {111} planes in the AgSbTe2. This would indicate that none of the material was single phase. Even though the Sb2Te3 in the measured specimens is present in quantities too small to be detected in our x‐ray powder photographs, it may have some effect on the measured properties. Therefore, the electrical properties of single‐phase AgSbTe2 have yet to be determined.} The lattice thermal conductivity is so low (0.0064 watts/cm°C at 290°K) that the calculated ``phonon mean free path'' is less than the nearest neighbor distance. The thermal conductivity of a specimen rich in AgSbTe2–Ag2Te eutectic is higher than that of either of the components. This excess thermal conductivity is attributed to circulating thermoelectric currents.