Giant transient Nernst–Ettingshausen effect in nearly gapless materials

We have measured a pulsed laser induced transient Nernst-Ettingshausen (TNE) effect for semimetal Bi and for nearly gapless materials Bi-Sb and Bi-Te alloy single crystals at 4.2 K and under magnetic fields up to 4 T. We have found the giant longitudinal-TNE (l-TNE) and transverse-TNE (t-TNE) signals for all materials. The l-TNE signals show a quite unusual antisymmetric magnetic field dependence, which suggests a mechanism of bipolar state caused by breakdown of space inversion symmetry.