(a) A conducting solid with a significant energy-dependent DOSs. (b) A junction of conducting solids A and B with different DOSs, which is the situation where the Seebeck effect was originally discovered. (c) A conducting solid with a steep energy dependence of the electron relaxation time τ. (d) A junction between two conducting solids of significantly different τ. The vertical axis denotes either N(ɛ) or τ(ɛ) at the Fermi level. The horizontal axis denotes temperature, or equivalently, the Fermi energy, due to their correlation. Note that scenarios c and d both produce a τ mismatch, which we exploit towards an enhanced Seebeck effect. When applying a magnetic field along the z direction, only in these two cases, transverse electric potential along the y direction (the Nernst effect) can be expected. In the case a and b, such a signal is fully compensated due to the Sondheimer cancellation (see text).