Berry curvature induced thermopower in type-I and type-II Weyl semimetals

Abstract

Berry curvature acts analogously to a magnetic field in the momentum-space, and it modifies the flow of charge carriers and entropy. This induces several intriguing magnetoelectric and magnetothermal transport phenomena in Weyl semimetals. Here, we explore the impact of the Berry curvature and orbital magnetization on the thermopower in tilted type-I and type-II Weyl semimetals, using semiclassical Boltzmann transport formalism. We analytically calculate the full magnetoconductivity matrix and use it to obtain the thermopower matrix for different orientations of the magnetic field (B), with respect to the tilt axis. We find that the tilt of the Weyl nodes induces linear magnetic field terms in the conductivity matrix, as well as in the thermopower matrix. The linear-B term appears in the Seebeck coefficients, when the B-field is applied along the tilt axis. Applying the magnetic field in a plane perpendicular to the tilt axis results in a quadratic-B planar Nernst effect, linear-B out-of-plane Nernst effect and quadratic-B correction in the Seebeck coefficient. arXiv:1903.01205v3 [cond-mat.mes-hall]

Chiral anomalies induced transport in Weyl metals in quantizing magnetic field

“…This manifests in the magnetothermal experiments in the form of positive magnetothermopower and positive magnetothermal conductivity [26][27][28][29], both of which have also been observed in recent experiments [30,31]. In addition to their manifestations in longitudinal magnetotransport, CAs have also been shown to give rise to the planar Hall effects in all transport coefficients [29,[32][33][34][35][36][37][38][39][40]. Recently, we predicted another anomaly, the thermal chiral anomaly in which a temperature gradient collinear with the magnetic field gives rise to charge and energy imbalance between the opposite chirality Weyl fermions [29].…”

“…So far we have explored the impact of CAs in the longitudinal magnetotransport coefficients. However, it has been shown that the origin of planar Hall effects and anisotropic longitudinal transport coefficients in nonmagnetic materials can also be related to CAs [32][33][34][35][36]. Here, we explore the impact of quantized LLs, on all the planar Hall transport coefficients and explore the possibility of quantum oscillations in them.…”

“…However, the bulk of the theoretical work till date has been focused on the semiclassical transport regime which displays a quadratic-B dependence of all transport coefficients [6,8,34,[41][42][43][44][45][46][47][48] or only in the ultraquantum regime [18] (see Fig. 1).…”

Thermal and gravitational chiral anomaly induced magneto-transport in Weyl semimetals

“…To explore the impact of anomalies on longitudinal magneto-resistance (MR), we define generic MR γ ≡ γ(B)/γ(0) − 1, where γ denotes the transport coefficients: σ, α,ᾱ, κ or S. To evaluate the MR, we need to add the Drude components to the respective transport coefficients. Evaluating the Drude components for each Weyl node [39], we have {σ s 0 , α s 0 ,κ s 0 } =…”

Energy magnetization and transport in systems with a non-zero Berry curvature in a magnetic field

“…Similarly, in response to a temperature gradient, without any external magnetic field, it generate a transverse Hall voltage, known as the anomalous Nernst effect [9,[12][13][14]. Coupled with the Boltzmann transport theory, the modified semiclassical equations have been employed to study transport in topological insulators [15], Chern Insulators [16], Weyl Semi-Metals [13,14,[17][18][19][20][21][22], Kondo Insulators [23], Rashba systems [24,25], optical lattices and quasicrystals [26,27], superconductors [28], non-Hermitian systems [29,30], as well as in various other systems [31][32][33][34][35][36][37]. Non-linear effects in transport have also been studied within this formalism [38][39][40][41][42][43].…”