Berry curvature induced anisotropic magnetotransport in a quadratic triple-component fermionic system

Abstract

Triple-component fermions (TCFs) are pseudospin-1 quasiparticles hosted by certain three-band semimetals in the vicinity of their band-touching nodes (2019 Phys. Rev. B 100 235201). The excitations comprise of a flat band and two dispersive bands. The energies of the dispersive bands are with and n = 1, 2, 3. In this work, we obtain the exact expression of Berry curvature, approximate form of density of states and Fermi energy as a function of carrier density for any value of n. In particular, we study the Berry curvature induced electrical and thermal magnetotransport properties of quadratic (n = 2) TCFs using semiclassical Boltzmann transport formalism. Since the energy spectrum is anisotropic, we consider two orientations of magnetic field (B): (i) B applied in the x–y plane and (ii) B applied in the x–z plane. For both the orientations, the longitudinal and planar magnetoelectric/magnetothermal conductivities show the usual quadratic-B dependence and oscillatory behavior with respect to the angle between the applied electric field/temperature gradient and magnetic field as observed in other topological semimetals. However, the out-of-plane magnetoconductivity has an oscillatory dependence on angle between the applied fields for the second orientation but is angle-independent for the first one. We observe large differences in the magnitudes of transport coefficients for the two orientations at a given Fermi energy. A noteworthy feature of quadratic TCFs which is typically absent in conventional systems is that certain transport coefficients and their ratios are independent of Fermi energy within the low-energy model.