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

Triple-component fermions (TCFs) are pseudospin-1 quasiparticles hosted by certain three-band semimetals in the vicinity of their band-touching nodes (2019Phys. Rev.B100235201). The excitations comprise of a flat band and two dispersive bands. The energies of the dispersive bands areE±=±αn2k⊥2n+vz2kz2withk⊥=kx2+ky2andn= 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 ofn. 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)Bapplied in thex-yplane and (ii)Bapplied in thex-zplane. For both the orientations, the longitudinal and planar magnetoelectric/magnetothermal conductivities show the usual quadratic-Bdependence 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.