Giant magnetoresistance and possible miniband effects in periodic magnetic fields

2D Electron Gas in Non-Uniform Magnetic Fields

“…To a good approximation one can then write the expected magnetoresistance as [12] The magnetic field profile at the 2D electrons is relatively easy to calculate and, when this is used to calculate Oc Eq. (3) gives good agreement with the measured low field magnetoresistance [12][13][14]. At low temperatures the temperature dependence of ΔRxx/R0 is found to follow that of µ2 [14].…”

“…Figure 9 shows measured Rxx plotted against z-component of the external magnetic field, Bextz , for Bext perpendicular to the plane of the 2DEG (g5 = 0°) and at 4 = 80° (note the logarithmic scale). The strong low field magnetoresistance oscillations are not Shubnikov-de Haas oscillations but result from commensurability between the diameter of the cyclotron orbit at the Fermi level and the period of the magnetic modulation [7][8][9][10][11][12][13][14]. These commensurability oscillations are closely related to those seen for electrostatic modulation [7,8].…”

“…For ϕ = 80° an additional very large low field magnetoresistance is also present. This arises because, at large 0, the amplitude of the z-component of the sign alternating magnetic field, due to the magnetisation of the stripes, is larger than Bext,z [12][13][14] as is shown in Fig. 10.…”

“…The transport properties of two-dimensional electron systems in 1D and 2D periodically modulated magnetic fields have been studied extensively [7][8][9][10][11][12][13][14]. The type of device used is illustrated schematically in Fig.…”

“…The more direct approach, which several groups [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] have pursued, is the fabrication of lithographically patterned ferromagnetic structures above near--surface 2DEGs. Micron or submicron ferromagnetic elements such as magnetic dots and stripes can be used to produce a range of field profiles at the 2DEG.…”