Orbital magnetic ratchet effect

Abstract

Magnetic ratchets -two-dimensional systems with superimposed non-centrosymmetric ferromagnetic gratings -are considered theoretically. It is demonstrated that excitation by radiation results in a directed motion of two-dimensional carriers due to pure orbital effect of the periodic magnetic field. Magnetic ratchets based on various two-dimensional systems like topological insulators, graphene and semiconductor heterostructures are investigated. The mechanisms of the electric current generation caused by both radiation-induced heating of carriers and by acceleration in the radiation electric field in the presence of space-oscillating Lorentz force are studied in detail. The electric currents sensitive to the linear polarization plane orientation as well as to the radiation helicity are calculated. It is demonstrated that the frequency dependence of the magnetic ratchet currents is determined by the dominant elastic scattering mechanism of two-dimensional carriers and differs for the systems with linear and parabolic energy dispersions.

Magnetic quantum ratchet effect in (Cd,Mn)Te- and CdTe-based quantum well structures with a lateral asymmetric superlattice

“…Finally we note, that while here we have dealt with a homogeneous magnetic field, the observed ratchet photocurrent in superlattices made of hard magnetic material (Dy) opens a possibility to study the ratchet effect driven by an inhomogeneous periodic magnetic field recently suggested in Refs. [33,45]. This kind of experiments would apply remnant magnetization of Dy together with the enhanced magnetic properties of DMS QWs and is a future task.…”

“…The DGG structure of sample 4 has been fabricated by depositing 75-nm-thick Dy and 15-nm-thick Au films. Premagnetizating the hard magnetic Dy-based superlattice enables realization of a magnetic ratchet which features an inhomogeneous magnetic field, recently suggested in [33,45].…”

Magnetic ratchet effect in bilayer graphene

“…The magnetic ratchet effect is a generic feature of inversionasymmetric two-dimensional systems [1][2][3][4][5][6][7][8]. It consists of the production of a dc electric current in response to a steady in-plane magnetic field B and an alternating electric field E, in the presence of inversion asymmetry.…”

Terahertz Electric Field Driven Electric Currents and Ratchet Effects in Graphene

“…Magnetic quantum ratchet effect has also been treated theoretically for bi‐layer graphene and graphene superimposed by an asymmetric lateral superlattice . The former work considered the orbital effect of an in‐plane magnetic field on electrons in bilayer graphene, deriving linear‐in‐field contributions to the low‐energy Hamiltonian arising from the presence of either skew interlayer coupling or interlayer potential asymmetry.…”