Absence of nonlocal resistance in microstructures of PbTe quantum wells

Abstract

We report on experiments allowing to set an upper limit on the magnitude of the spin Hall effect and the conductance by edge channels in quantum wells of PbTe embedded between PbEuTe barriers. We reexamine previous data obtained for epitaxial microstructures of n-type PbSe and PbTe, in which pronounced nonlocal effects and reproducible magnetoresistance oscillations were found. Here we show that these effects are brought about by a quasi-periodic network of threading dislocations adjacent to the BaF 2 substrate, which give rise to a p-type interfacial layer and an associated parasitic parallel conductance. We then present results of transport measurements on microstructures of modulation doped PbTe/(Pb,Eu)Te:Bi heterostructures for which the influence of parasitic parallel conductance is minimized, and for which quantum Hall transport had been observed, on similar samples, previously. These structures are of H-shaped geometry and they are patterned of 12 nm thick strained PbTe quantum wells embedded between Pb 0.92 Eu 0.08 Te barriers. The structures have different lateral sizes corresponding to both diffusive and ballistic electron transport in non-equivalent L valleys. For these structures no nonlocal resistance is detected confirming that PbTe is a trivial insulator. The magnitude of spin Hall angle g is estimated to be smaller than 0.02 for PbTe/PbEuTe microstructures in the diffusive regime.

Signatures of dephasing by mirror-symmetry breaking in weak-antilocalization magnetoresistance across the topological transition in Pb1−xSnxSe

“…Despite that ARPES data presented in Figs. 4(a)-4(d) confirm the expected n-type character of Pb 1−x Sn x Se, a positive sign of the Hall coefficient is observed, pointing out to a relatively large contribution from holes at the interface to BaF 2 , as found earlier for PbTe/BaF 2 epilayers [51]. Highfield parabolic positive MR for the field perpendicular to the film plane, shown in Figs.…”

Nonlocal resistance and its fluctuations in microstructures of band-inverted HgTe/(Hg,Cd)Te quantum wells

“…Otherwise, a false nonlocal signal may occur, as it was recently demonstrated in Hall microstructures of PbTe. 37 Therefore, only a series of nonlocal voltage measurements, taken between consecutive contact probes distributed around the structure perimeter, confirms the edge conduction. Here we have shown that in the depletion regime, electric potential measured around the circumference of the structure is really compatible with the edge conduction picture.…”

All‐electrical detection of spin Hall effect in semiconductors

“…Corresponding measurements were reported by Brüne et al for HgTe microstructures and by Mihajlović et al for Au Hall bars. Kolwas et al carried out measurements in PbTe quantum wells and a similar setup was also used by Balakrishnan et al to experimentally determine the strength of spin–orbit coupling in graphene. However, reports for semiconductors are still rare.…”