Investigation of a New Type of Oscillations in the Magnetoresistance

Abstract

A new type of oscillations in the transverse magnetoresistanee of nondegenerate semiconductors due to inelastic scattering of electrons by optical phonons was theoretically predicted by Gurevich and Firsov. 1 This new effect can be observed if the phonon spectrum of the crystal has an optical branch and if the magnetic field is sufficiently strong to satisfy the condition ftr = iiH/c = (erH/m*c)» 1, where Q is the cyclotron frequency, r is the electronic relaxation time, and ji is the electronic mobility. Later Efros 2 generalized the Gurevich-Firsov theory for degenerate statistics.The physical nature of these oscillations can be explained as follows. At very high magnetic field the distance between the adjacent Landau levels, HQ,, exceeds the longitudinal optical phonon energy, HQJ Q , and the probability of electron-phonon scattering is relatively small. When the magnetic field decreases, the Landau splitting energy H£l becomes equal to HOJ Q . Then the probability of electron-phonon scattering sharply increases, causing the p xx component of the resistivity tensor to increase (the magnetic field H is supposed to be oriented along the z axis).Further decrease of the magnetic field breaks the resonance condition, and the number of transitions induced by optical phonons is decreased until a new resonance is approached. The resonance condition is a> 0 = M£2, where M is an integer. Thus the part of the magnetoresistanee due to scattering by optical phonons should oscillate with a period A(l/#) =e/m*u> 0 c, a)depending on the effective mass m* and co 0 .We have also investigated theoretically similar oscillations of the longitudinal magnetoresistanee for the case of low temperatures, where (fiw 0 /kT) 10 15 20 25 30 35 Kkgauss FIG.

Strong magnetophonon oscillations in extra-large graphene

“…These advances are mostly due to graphene’s intrinsically high carrier mobility that is preserved by state-of-the-art heterostructure engineering in which graphene is encapsulated between hexagonal boron nitride layers 13,14 and electrically tuned with atomically smooth metallic gates 8,15 . Nonetheless, one of the first discoveries in quantum transport, well known for over 50 years 16,17 , has remained conspicuously absent in graphene–magnetophonon oscillations 18,19 .…”

Magnetophonon spectroscopy of Dirac fermion scattering by transverse and longitudinal acoustic phonons in graphene

“…In 1961, theoretical work by Gurevich and Firsov predicted that inelastic scattering of electrons by phonons can induce oscillations in the magnetoresistance of semiconductors 1 . Magnetophonon resonance (MPR) has since been used to probe spectroscopically electron-phonon interactions in a wide range of bulk semiconductors [2][3][4][5] and semiconductor heterostructures in which carriers are confined in two-dimensions (2D) by a quantum well potential [6][7][8][9][10] .…”

Probing electronic structures of graphene under magnetic field and electric field by Raman spectroscopy

“…Thus, the energy and lifetime of the specific phonon could be dramatically affected when MPR happens. MPR was predicted and experimentally observed in early 1960s by Firsov et al [29]. Many experiments were carried out on MPR effect of semiconductors since its discovery [30][31][32].…”

“…Magneto-phonon resonance is an effect which occurs when the phonon energy of the material equals to the separation between Landau levels. The physical nature of this MPR can be understood that the possibility of phonon-electron interaction will sharply increase when MPR occurs [29]. Thus, the energy and lifetime of the specific phonon could be dramatically affected when MPR happens.…”

“…The intensity ratio of the D peak and G peak is increasing from 0.05, 0.86 to 2.75 with the dosage values increasing from 0.03, 0.3 to 3 nC/μm 2 . It implies that more disorder was introduced into graphene lattice when the D peak intensity wasMajor part of this chapter is adapted from Shen, X. et al, Nanoscale 2013, 5, 3352-3358 29.…”