van Kruining Koen, Hayrapetyan Armen G, Götte Jörg B
Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany.
Nanjing University, Nanjing 210093, China.
Phys Rev Lett. 2017 Jul 21;119(3):030401. doi: 10.1103/PhysRevLett.119.030401. Epub 2017 Jul 18.
We present a relativistic description of electron vortex beams in a homogeneous magnetic field. Including spin from the beginning reveals that spin-polarized electron vortex beams have a complicated azimuthal current structure, containing small rings of counterrotating current between rings of stronger corotating current. Contrary to many other problems in relativistic quantum mechanics, there exists a set of vortex beams with exactly zero spin-orbit mixing in the highly relativistic and nonparaxial regime. The well-defined phase structure of these beams is analogous to simpler scalar vortex beams, owing to the protection by the Zeeman effect. For states that do show spin-orbit mixing, the spin polarization across the beam is nonuniform rendering the spin and orbital degrees of freedom inherently inseparable.
我们给出了均匀磁场中电子涡旋束的相对论描述。从一开始就考虑自旋表明，自旋极化的电子涡旋束具有复杂的方位电流结构，在较强的同向旋转电流环之间包含反向旋转电流的小环。与相对论量子力学中的许多其他问题相反，在高度相对论性和非傍轴区域存在一组自旋 - 轨道混合恰好为零的涡旋束。由于塞曼效应的保护，这些束的明确定义的相位结构类似于更简单的标量涡旋束。对于确实表现出自旋 - 轨道混合的态，束上的自旋极化是不均匀的，使得自旋和轨道自由度本质上不可分离。
