Unusual anisotropy of inplane field magnetoresistance in ultra-high mobility SiGe/Si/SiGe quantum wells

Abstract

We find an unusual anisotropy of the inplane field magnetoresistance with higher resistance in the parallel orientation of the field, B , and current, I, in ultra-high mobility SiGe/Si/SiGe quantum wells. The anisotropy depends on the orientation between the inplane field and current relative to the crystallographic axes of the sample and is a consequence of the ridges on the quantum well surface. For the parallel or perpendicular orientations between current and ridges, a method of converting the magnetoresistance measured at I ⊥ B into the one measured at I B is suggested and is shown to yield results that agree with the experiment.

Chapter 2. Metal-Insulator Transition in a Strongly Correlated Two-Dimensional Electron System

“…The interest in flat-band materials [59,60,61,62] is ignited, in particular, by the fact that, due to the anomalous density of states, the flattening of the band may be important for the construction of room temperature superconductivity. The appearance of a flat band is theoretically predicted [49,63,64] in heavy fermions, high-temperature superconducting materials, 3 He, and twodimensional electron systems. As the strength of fermion-fermion interaction is increased, the single-particle spectrum becomes progressively flatter in the vicinity of the Fermi energy eventually forming a plateau.…”

“…The first set were ultra-high mobility SiGe/Si/SiGe quantum wells described in detail in Refs. [2,3]. The peak electron mobility, µ, in these samples reaches 240 m 2 /Vs.…”

Metallic state in a strongly interacting spinless two-valley electron system in two dimensions

“…The samples studied are SiGe/Si/SiGe quantum wells of unprecedented quality similar to those described in detail in Refs. [37,38]. The peak electron mobility in these samples reaches 240 m 2 /Vs.…”

Spin effect on the low-temperature resistivity maximum in a strongly interacting 2D electron system

“…The in-plane magnetic field was perpendicular to the current to exclude the influence of ridges on the quantum well surface on the resistance measured at high electron densities (for more details, see Refs. 60 , 61 ). Measurements were carried out in an Oxford TLM-400 dilution refrigerator with a base temperature of mK.…”