Manifestation of strong correlations in transport in ultraclean SiGe/Si/SiGe quantum wells

Spin effect on the low-temperature resistivity maximum in a strongly interacting 2D electron system

“…The data in B = 0 scale perfectly in a wide range of electron densities and are described well by the theory in the weak-disorder limit; deviations from the theoretical curve become pronounced for T > T max at low electron densities, similar to the results of Ref. [18]. The curve for the highest electron density in B = B * follows the theoretical dependence at all temperatures.…”

“…Notably, similar behavior of the resistivity ρ(T ) can be expected within the screening theory in its general form (for more on this, see Ref. [18]).…”

“…For comparison, in B = 0, the ρ(T ) data follow the predicted theoretical dependence [21,22] in a modest range of electron densities, according to Ref. [18]. This is not particularly surprising because the renormalization-group scaling theory holds only in the immediate vicinity of the metal-insulator transition for the resistivities low compared to πh/e 2 .…”

“…The strength of such a resistivity drop varies from system to system, reaching a 12-fold value in ultra-pure SiGe/Si/SiGe quantum wells [9]. From the theoretical standpoint, the Wigner-Mott scenario and the associated dynamical mean-field theory (DMFT) approach [15][16][17], which view the strong electron-electron interactions as the main driving force for the MIT, have been remarkably successful in providing a quantitative description of the low-temperature resistivity drop in all these systems, especially in SiGe/Si/SiGe quantum wells [18]. The experimental ratio (ρ(T ) − ρ(0))/(ρ(T max ) − ρ(0)) has been found to be a universal function of T /T max , which is consistent with the DMFT.…”

Spin effect on the low-temperature resistivity maximum in a strongly interacting 2D electron system

“…The increase of the effective mass with decreasing electron density 8 , 9 , 13 , 14 , 21 – 24 suggests that the effect of strong electron-electron interactions is the main driving force for the experimentally observed metal-insulator transition due to the fermion condensation 24 , 25 or the Wigner-Mott transition 26 , 27 . From the theoretical standpoint, the dynamical mean-field theory (DMFT) approach 26 , 28 , 29 has provided a successful quantitative description of the low-temperature resistivity drop in zero magnetic field in all these systems, especially in SiGe/Si/SiGe quantum wells 30 . Over a wide range of electron densities, the experimental ratio has been found to be a universal function of , which is consistent with the DMFT.…”