Mesoscopic Phenomena in Microstructures of IV-VI Epilayers

Abstract

Magnetoresistance measurements of photolithographically patterned PbSe and Pb1-y Mnx Se microstructures were performed. Reproducible magnetoconductance fluctuations with the amplitude increasing with decreasing temperature were observed. Unexpectedly, these fluctuations contain a component periodic in the magnetic field, and their magnitude is greater than that expected from the current theory of the universal conductance fluctuations. Possible explanations are discussed. PACS numbers: 71.55.JvIt is generally accepted by now that because of Aharonov-Bohm interference of scattered waves, the conductance of any disordered conductor should exhibit aperiodic fluctuations as a function of the magnetic field. The mean amplitude of these fluctuations increases with decreasing length L of the sample and starts to be universal, i.e., independent of the material that the sample is made of, AG N 0.5e2 /h, once L becomes smaller than the phase breaking length Lϕ(T) [1,2]. Accordingly, the phenomenon is known under the name of universal conductance fluctuations (UCF). Indeed, a series of beautiful millikelvin experiments with nanostructures of nonmagnetic metals has fully confirmed the theoretical predictions [3]. In the case of semiconductors, however, the situation is less clear. In particular, the presence of a component periodic in the magnetic field has been detected in microstructures of n+ GaAs (551)

Conductance fluctuations in PbTe wide parabolic quantum wells

“…The only requirement is the possibility for scattering of edge electrons to the 3D electron system at the contacts. In contrast, recently observed CF in other IV-VIepilayers, particularly PbSe and Pb 1-x Mn x Se single layers of thickness ranging from 1.5 -3 µm, exhibit a clearly non-universal amplitude which changes with the magnetic field [18,19]. However, there are no non-local data which would allow a more detailed comparison with our results.…”

Conductance Fluctuations in PbSe: Manifestation of Ballistic Transport in Macroscale?

“…In our previous works [1,2] we undertook a study of mesoscopic phenomena in microstuctures of lead chalcogenides. Magnetotransport data have clearly shown the existence of quasi-periodic, reproducible conductance fluctuations in the microstructures of Pb1-x Mn x Se (0 < x < 2%).…”