Is it possible to make a thermoelectric nanomaterials which has figure of merit=100 even if the the material is ballistic and the Manybody localization transition parameter is large.
no no, FOM=100, not FOM=1 has been already achieved , even FOM=2 also can be achieved from nanostructured materials. so I am asking about FOM>= 10^x, x>=2.
The FOM is a measure for the efficiency, not equal the efficiency. If the FOM is infinitely, the efficiency corresponds to the Carnot-efficiency. In principly, high FOM numbers are possible, because FOM=100 doesn't mean 100%. Practically see the answer of H. Pandey. Furthermore, in the case of ballistic transport the conductivity is high but the thermal conductivity too, because there is no backscattering of electrons, e.g. the ratio is 0/0 and therefore undetermined. The maximum you can reach, is the Carnot-efficiency what depends from the temperature difference only.