Breathing mode in open-orbit magnetotransport: a magnetic lens with a quantum mechanical focal length

TL;DR

This paper introduces a quantum mechanical breathing mode in open-orbit magnetotransport, where electrons periodically spread and refocus, with a focal length dependent on Planck's constant, differing from classical magnetic focusing.

Contribution

It reveals a novel quantum breathing mode in electron propagation with a focal length proportional to 5, distinct from classical effects, expanding understanding of quantum magnetotransport phenomena.

Findings

Identified a quantum breathing mode in open-orbit electron propagation.

Demonstrated the mode's focal length depends on 5, not classical parameters.

Showed the effect is intrinsic to quantum mechanics, not classical cyclotron motion.

Abstract

We consider the propagation of electrons in a lattice with an anisotropic dispersion in the $x$--$y$ plane (lattice constant $a$), such that it supports open orbits along the $x$-axis in an out-of-plane magnetic field $B$. We show that a point source excites a "breathing mode", a state that periodically spreads out and refocuses after having propagated over a distance $\ell =(eaB/h)^{-1}$ in the $x$-direction. Unlike known magnetic focusing effects, governed by the classical cyclotron radius, this is an intrinsically quantum mechanical effect with a focal length $\propto\hbar$.