Abstract
We study experimentally and theoretically the temperature dependence of transverse magnetic routing of light emission from hybrid plasmonic-semiconductor quantum well structures where the exciton emission from the quantum well is routed into surface plasmon polaritons propagating along a nearby semiconductor-metal interface. In II-VI and III-V direct band semiconductors the magnitude of routing is governed by the circular polarization of exciton optical transitions, that is induced by a magnetic field. For structures comprising a (Cd,Mn)Te/(Cd,Mg)Te diluted magnetic semiconductor quantum well we observe a strong directionality of the emission up to 15% at low temperature of 20 K and magnetic field of 485 mT due to giant Zeeman splitting of holes mediated via the strong exchange interaction with Mn$^{2+}$ ions. For increasing temperatures towards room-temperature the magnetic susceptibility decreases and the directionality strongly decreases to 4% at T = 45 K. We also propose an alternative design based on a non-magnetic (In,Ga)As/(In,Al)As quantum well structure, suitable for higher temperatures. According to our calculations, such structure can demonstrate emission directionality up to 5% for temperatures below 200 K and moderate magnetic fields of 1 T.
Highlights
Recent achievements in nanotechnology boosted rapid development of magnetophotonics—an emerging field where a magnetic field is used to alter the optical response of nanophotonic structures, e.g., amplitude, phase, and polarization of the electromagnetic wave transmitted through the structure [1]
Significant progress has been achieved by combination of noble metals with magnetic materials resulting in hybrid plasmonic structures, where the magnetic field induces a substantial modulation of optical spectra and their polarization in the vicinity of plasmonic resonances due to enhancement of the Faraday or Kerr magneto-optical effects [7,8]
Using the approach based on spinmomentum locking we have recently demonstrated transverse magnetic routing of light emission (TMRLE) for diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum well (QW) structures where the directional emission of excitons in Published by the American Physical Society
Summary
Recent achievements in nanotechnology boosted rapid development of magnetophotonics—an emerging field where a magnetic field is used to alter the optical response of nanophotonic structures, e.g., amplitude, phase, and polarization of the electromagnetic wave transmitted through the structure [1]. This effect is termed spin-momentum locking [17,18]: Evanescent plasmons carry so-called transverse spin ∝ kSPP × z. Because of the spin-momentum locking effect for surface plasmons, elliptically polarized excitons are directionally coupled to either left- or right-propagating plasmons, depending on the transition ellipticity defined by the sign of Pc. Phenomenologically, the emitted surface plasmons propagate predominantly along one of the directions perpendicular to the magnetic field given by the wave vector kSPP ∝ B × ez [see Fig. 1(a)]. V considers alternative (i.e., temperature independent), nonmagnetic structures (without magnetic ions) for the realization of TMRLE across a wide temperature range
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