Multipocket synergy towards high thermoelectric performance in topological semimetal TaAs2
Haihua Hu, Xiaolong Feng, Yu Pan, Vicky Hasse, Honghui Wang, Bin He, Claudia Felser
Abstract
Abstract Charge-carrier compensation in topological semimetals amplifies the Nernst signal and simultaneously degrades the Seebeck coefficient. In this study, we report the simultaneous achievement of both a large Nernst signal and an unsaturating magneto-Seebeck coefficient in a topological nodal-line semimetal TaAs 2 single crystal. The unique dual-high transverse and longitudinal thermopowers are attributed to multipocket synergy effects: the combination of a strong phonon-drag effect and the two overlapping highly dispersive conduction and valence bands with electron–hole compensation and high mobility, promising a large Nernst effect; the third Dirac band causes a large magneto-Seebeck effect. High transverse and longitudinal power factors of ~3100 and ~50 μW cm −1 K −2 , respectively, are achieved, surpassing those of other topological semimetals and mainstream semiconductors. Our study presents a feasible approach for optimizing the longitudinal and transverse thermopowers in topological semimetals simultaneously and demonstrates the potential of TaAs 2 for low temperature solid-state cooling.