Thermoelectrics of type-I and type-II nodal line semimetals within the two-band model
Jyesta Mahayu Adhidewata (a*), Ahmad Ridwan T. Nugraha (b**), Eddwi H. Hasdeo (b)(c), Bobby Eka Gunara (a***)

(a) Theoretical High Energy Physics Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132, Indonesia
*jyesta.mahayu[at]s.itb.ac.id
(b) Research Center for Physics, Indonesian Institute of Sciences (LIPI), Tangerang Selatan 15314, Indonesia
**ahmad.ridwan.tresna.nugraha[at]lipi.go.id
(c) Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg, Luxembourg
***bobby[at]fi.itb.ac.id

Abstract

Metals and semimetals are often considered bad thermoelectric (TE) materials due to their low Seebeck coefficients. However, in this work, we would like to show that topological semimetals in the class of nodal-line semimetals could potentially have a higher than average performance as TE materials. Nodal-line semimetals (NLSs) are bulk semimetals with an intersection between the conduction band and valence band in the form of a line (thus called the nodal line). We construct a two-band model using an almost-linear conduction and parabolic (or Mexican-hat) valence bands which overlap near the band edge to represent a type-I (or type-II) NLS. We calculate TE properties of the NLSs using the semiclassical Boltzmann transport theory with the relaxation time approximation. We expect to obtain a large enough Seebeck coefficient from the presence of a discontinuity in the density of states due to band overlap. Here we seek to optimize the parameters of our model which will hopefully allow us to determine potential candidates for TE materials among semimetals.

Keywords: Boltzmann transport equation, nodal-line semimetal, thermoelectrics

Topic: Materials Physics