Enhanced thermoelectric performance by van Hove singularities in the density of states of type-II nodal-line semimetals
Journal
Physical Review B
Journal Volume
105
Journal Issue
11
Start Page
115142
ISSN
24699950
24699969
Date Issued
2022
Author(s)
Abstract
The effects of the unique density of states (DOS) of a topological type-II nodal-line semimetal (NLS) on its thermoelectric (TE) transport properties are investigated through a combination of semianalytical and first-principles methods with "spinless Mg3Bi2"as the artificial material. The DOS in such a type-II NLS possesses two van Hove singularities near the energy of the nodal line that leads to a large S value compared to the normal metals. Combined with the linear band at the nodal line that gives high electrical conductivity σ, the type-II NLS can exhibit a relatively high TE power factor (PF=S2σ) at the nodal line. In particular, we find PF?60 μW/cmK2 at 300 K for the n-type Mg3Bi2 by considering the electron-phonon scattering, in which the relaxation time τ of carriers can be expressed as τ?DOS-1 for the type-II NLS. Furthermore, we optimize parameters for the TE power factor of type-II NLSs in general by adopting the two-band model with the DOS-dependent relaxation-time approximation. Our results suggest the type-II NLSs as a potential class of high-performance TE materials among metals and semimetals, which are traditionally considered inadequate TE materials compared to semiconductors.
Subjects
Binary Alloys
Bismuth Alloys
Electric Power Factor
Magnesium Alloys
Phonons
Thermoelectricity
Densities Of State
Nodal Line
Semi-analytical
Thermo-electric Materials
Thermoelectric Material
Thermoelectric Performance
Thermoelectric Power Factors
Thermoelectric Transport Properties
Type Ii
Van Hove Singularities
Relaxation Time
Publisher
American Physical Society
Type
journal article