We present an investigation of the optical constants of the near stoichiometric GdN films. Transmission and reflection spectra are collected for the paramagnetic and the ferromagnetic GdN in the photon energy range of...We present an investigation of the optical constants of the near stoichiometric GdN films. Transmission and reflection spectra are collected for the paramagnetic and the ferromagnetic GdN in the photon energy range of 0.5-5.5 eV. In the ferromagnetic phase, behaviors of minority and majority spin states are specifically focussed on, which indicate spin-split joint density of states. The results confirm the LSDA＋U estimates of energy gap associated with the majority-spins and also the magnitude of spin splitting.展开更多
The spin-polarized band structures of an ultrathinheterostructure are calculated via first-principles density functional theory.The electron–phonon interaction and the superconducting properties of the ultrathinheter...The spin-polarized band structures of an ultrathinheterostructure are calculated via first-principles density functional theory.The electron–phonon interaction and the superconducting properties of the ultrathinheterostructure are studied by using the fully anisotropic Migdal–Eliashberg theory powered by Wannier–Fourier interpolation.Due to the complex Fermi surface in this low-dimensional system,the electron–phonon interaction and the superconducting gap display significant anisotropy.The temperature dependence of the superconducting gap can be fitted by solving numerically the Bardeen–Cooper–Schrieffer(BCS)gap equation with an adjustable parameter α,suggesting that phonon-mediated mechanism as its superconducting origin.Large Rashba spin-splitting and superconductivity coexist in this heterostructure,suggesting that this hybrid low-dimensional system will have some specific applications.展开更多
Transport characteristics of single crystal bismuth films on Si（111）-7×7 are found to be metallic or insulating at temperature below or above Tc, respectively. The transition temperature Tc decreases as the fil...Transport characteristics of single crystal bismuth films on Si（111）-7×7 are found to be metallic or insulating at temperature below or above Tc, respectively. The transition temperature Tc decreases as the film thickness increases. By combining thickness dependence of the films resistivity, we find the insulating behaviour results from the states inside film, while the metallic behaviour originates from the interface states. We show that quantum size effect in a Bi film, such as the semimetal-to-semiconductor transition, is only observable at a temperature higher than Tc.展开更多
文摘We present an investigation of the optical constants of the near stoichiometric GdN films. Transmission and reflection spectra are collected for the paramagnetic and the ferromagnetic GdN in the photon energy range of 0.5-5.5 eV. In the ferromagnetic phase, behaviors of minority and majority spin states are specifically focussed on, which indicate spin-split joint density of states. The results confirm the LSDA＋U estimates of energy gap associated with the majority-spins and also the magnitude of spin splitting.
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20141441)
文摘The spin-polarized band structures of an ultrathinheterostructure are calculated via first-principles density functional theory.The electron–phonon interaction and the superconducting properties of the ultrathinheterostructure are studied by using the fully anisotropic Migdal–Eliashberg theory powered by Wannier–Fourier interpolation.Due to the complex Fermi surface in this low-dimensional system,the electron–phonon interaction and the superconducting gap display significant anisotropy.The temperature dependence of the superconducting gap can be fitted by solving numerically the Bardeen–Cooper–Schrieffer(BCS)gap equation with an adjustable parameter α,suggesting that phonon-mediated mechanism as its superconducting origin.Large Rashba spin-splitting and superconductivity coexist in this heterostructure,suggesting that this hybrid low-dimensional system will have some specific applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10874217 and 10427402)the National Basic Research Program of China(973 Program)(Grant No.2006CB933000)
文摘Transport characteristics of single crystal bismuth films on Si（111）-7×7 are found to be metallic or insulating at temperature below or above Tc, respectively. The transition temperature Tc decreases as the film thickness increases. By combining thickness dependence of the films resistivity, we find the insulating behaviour results from the states inside film, while the metallic behaviour originates from the interface states. We show that quantum size effect in a Bi film, such as the semimetal-to-semiconductor transition, is only observable at a temperature higher than Tc.
