Anomalous Exciton Hall Effect Kozin, V K; Shabashov, V A; Kavokin, A V ...
Physical review letters,
2021-Jan-22, Volume:
126, Issue:
3
Journal Article
Peer reviewed
Open access
It is well known that electrically neutral excitons can still be affected by crossed electric and magnetic fields that make them move in a direction perpendicular to both fields. We show that a ...similar effect appears in the absence of external electric fields, in the case of scattering of an exciton flow by charged impurities in the presence of the external magnetic field. As a result, the exciton flow changes the direction of its propagation that may be described in terms of the Hall conductivity for excitons. We develop a theory of this effect, which we refer to as the anomalous exciton Hall effect, to distinguish it from the exciton Hall effect that arises due to the valley selective exciton transport in transition metal dichalcogenides. According to our estimations, the effect is relatively weak for optically active or bright excitons in conventional GaAs quantum wells, but it becomes significant for optically inactive or dark excitons, because of the difference of the lifetimes. This makes the proposed effect a convenient tool for spatial separation of dark and bright excitons.
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The positron annihilation lifetimes were measured using a 48V positron source in noncentrosymmetric cubic single crystals of CoSi, FeSi and MnSi. The following lifetimes were determined from the ...positron annihilation time spectra: 168(1) ps for CoSi, 114(1) ps for FeSi and 111(1) ps for MnSi. For single-crystal CoSi, the positron annihilation lifetime was also determined with a 22Na positron source. For CoSi, the lifetimes obtained from different positron sources are consistent. The differences in the positron annihilation lifetimes in MnSi and FeSi, on the one hand, and in the Weyl semimetal CoSi, on the other hand, are possibly caused by the formation of a positron + electron bound state (positronium).
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Abstract
The anomalous exciton Hall effect is a phenomenon that occurs in a quantum well in the presence of an external magnetic field applied perpendicular to the surface due to the interaction of ...the exciton dipole moment with an electric field, formed by the charged impurities. The effect was fully described in 1 for different magnetic field regimes. In this paper, we focus on the way the perturbation method was used for finding the ground state energy of an exciton in the limit of a weak magnetic field.
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