By generalizing the isotope effect for elemental superconductors (SCs) to the case of pairing in the 2-phonon exchange mechanism for composite SCs, we give here an explanation of the well-known increase in the critica...By generalizing the isotope effect for elemental superconductors (SCs) to the case of pairing in the 2-phonon exchange mechanism for composite SCs, we give here an explanation of the well-known increase in the critical temperature (Tc) of Bi2Sr2CaCu2O8 from 95 K to 110 K and of Bi2Sr2Ca2Cu3O10 from 105 to 115 - 125 K when Bi and Sr in these are replaced by Tl and Ba, respectively. On this basis, we also give the estimated Tcs of some hypothetical SCs, assuming that they may be fabricated by substitutions similar to Bi → Tl and Sr → Ba.展开更多
We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, pie...We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, piezoelectric scattering （PE）, and polar-optic phonon scattering （POP）. We find that DE and PE are the more significant limiting factors at intermediate temperatures of 40 K to 250 K, while POP becomes dominant as room temperature is approached. Detailed numerical results are presented for the change of electron mobility with respect to temperature and carrier density. We conclude that these three types of phonon scattering, which are generally determined by the material properties but not the technical processing, are hard limits to the 2DEG mobility.展开更多
文摘By generalizing the isotope effect for elemental superconductors (SCs) to the case of pairing in the 2-phonon exchange mechanism for composite SCs, we give here an explanation of the well-known increase in the critical temperature (Tc) of Bi2Sr2CaCu2O8 from 95 K to 110 K and of Bi2Sr2Ca2Cu3O10 from 105 to 115 - 125 K when Bi and Sr in these are replaced by Tl and Ba, respectively. On this basis, we also give the estimated Tcs of some hypothetical SCs, assuming that they may be fabricated by substitutions similar to Bi → Tl and Sr → Ba.
基金supported in part by the Grainger Center for Electric Machinery and Electromechanics of the University of Illinois
文摘We theoretically present the intrinsic limits to electron mobility in the modulation-doped AIGaN/GaN two-dimensional electron gas （2DEG） due to effects including acoustic deformation potential （DP） scattering, piezoelectric scattering （PE）, and polar-optic phonon scattering （POP）. We find that DE and PE are the more significant limiting factors at intermediate temperatures of 40 K to 250 K, while POP becomes dominant as room temperature is approached. Detailed numerical results are presented for the change of electron mobility with respect to temperature and carrier density. We conclude that these three types of phonon scattering, which are generally determined by the material properties but not the technical processing, are hard limits to the 2DEG mobility.
