Thermoelectric transport of the half-filled lowest Landau level in a p -type Ge/SiGe heterostructure

We investigate the thermoelectric transport properties of the half-filled lowest Landau level $v=1/2$ in a gated two-dimensional hole system in a strained Ge/SiGe heterostructure. The electron-diffusion dominated regime is achieved below 600 mK, where the diffusion thermopower ${{S}_{xx}}^{d}$ at $v=1/2$ shows a linear temperature dependence. In contrast, the diffusion-dominated Nernst signal ${{S}_{xy}}^{d}$ of $v=1/2$ is found to approach zero, which is independent of the measurement configuration (sweeping magnetic field at a fixed hole density or sweeping the density by a gate at a fixed magnetic field).