Phonon Drag and Carrier Diffusion Contributions in Thermoelectric Power of M3C60 (M = K, Rb) Fullerides
D. Varshneya and N. Singhb
aMaterials Science Laboratory, School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore, 452001, India
bDepartment of Physics, Ranchi College, Ranchi University Ranchi, Jharkhand, 834008, India
Received: July 21, 2012
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The thermoelectric power (S) of M3C60 (M = K, Rb) alkali intercalated fullerides is theoretically investigated by considering the Mott expression within parabolic band approximation to reveal the electron diffusive thermoelectric power (Scdiff). We follow the Fermi energy as electron parameter and Scdiff discerned linear temperature dependence. S infers a change in slope above transition temperature and becomes almost linear above 70 K for M3C60 alkali intercalated fullerides. As a next step, the phonon drag thermoelectric power (Sphdrag) is computed within relaxation time approximation when thermoelectric power is limited by scattering of phonons from defects, grain boundaries, phonons and electrons as carriers. It is noticed that the Sphdrag of K3C60 is anomalous and it is an artifact of strong phonon-electron and -phonon scattering mechanism. The thermoelectric power within relaxation time approximation has been taken into account ignoring a possible energy dependence of the scattering rates. Behaviour of S(T) is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions in M3C60 (M = K, Rb) alkali intercalated fullerides.

DOI: 10.12693/APhysPolA.123.752
PACS numbers: 74.70.Wz, 74.25.fg, 74.25.Kc