Band alignment in SiC-based one-dimensional van der Waals homojunctions

The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial strain and an external electric field. According to the calculated results, the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-II band alignment and robust electronic structures with different diameters or widths. Furthermore,the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-I band alignment, respectively, in a range of[-0.3,-0.1] V/A and [0.1, 0.3] V/A and change into metal when the electric field intensity is equal to or higher than0.4 V/A. Interestingly, the SiCNTs/SiCNRs 1D vdWhs have robust electronic structures under axial strain. These findings demonstrate theoretically that the SiCNTs/SiCNRs 1D vdWhs can be employed in nanoelectronics devices.

Grüneisen ratio quest for self-duality of quantum criticality in a spin-1/2 XY chain with Dzyaloshinskii–Moriya interaction

The quantum phase transition(QPT)and quantum criticality of an anisotropic spin-1/2 XY chain under the interplay of magnetic field and Dzyaloshinskii-Moriya(DM)interaction,which is interpreted as an electric field,are investigated,wherein the anisotropic parameter plays a similar role as the superconducting pairing gap in the interacting Kitaev topological superconductor model that protects the topological order.It is shown that the thermal Drude weight is a good quantity to characterize the gapped(D_(th)=0)and gapless(D_(th)>0)ground states.The continuous QPT is marked by a quantum critical point(QCP)associated with entropy accumulation,which is manifested by a characteristic Güneisen ratio(GR)with or without selfduality symmetry.It is shown that at a self-dual QCP,the GR keeps a finite value as T→0,while at a general QCP without self-duality symmetry,it displays a power-law temperature dependent divergence:Γ(T,r_(c))∼±T^(−1),which provides a novel thermodynamic means for probing QPT.