The spin-orbit interaction generally leads to spin splitting (SS) of electron and hole energy states in solids, a splitting that is characterized by a scaling with the wavevector $bf k$. Whereas for {it 3D bulk zincblende} solids the electron (heavy
hole) SS exhibits a cubic (linear) scaling with $k$, in {it 2D quantum-wells} the electron (heavy hole) SS is currently believed to have a mostly linear (cubic) scaling. Such expectations are based on using a small 3D envelope function basis set to describe 2D physics. By treating instead the 2D system explicitly in a multi-band many-body approach we discover a large linear scaling of hole states in 2D. This scaling emerges from hole bands coupling that would be unsuspected by the standard model that judges coupling by energy proximity. This discovery of a linear Dresselhaus k-scaling for holes in 2D implies a different understanding of hole-physics in low-dimensions.
We have made a phase-sensitive measurement on the corner junction of the iron-based superconductor BaFe1.8Co0.2As2, and observed the typical Fraunhofer-like diffraction pattern. The result suggests that there is no phase shift between the a-c face an
d b-c face of a crystal, which indicates that the superconducting wavefunction of the iron based superconductor is different from that of a cuprate superconductor.
