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Register a new userPiezoplasmonics: strain-induced tunability of plasmon resonance in AlAs quantum wells
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Added by
Viacheslav Muravev Dr.
Publication date
2020
fields
Physics
and research's language is
English
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We demonstrate tuning of two-dimensional (2D) plasmon spectrum in modulation-doped AlAs quantum wells via the application of in-plane uniaxial strain. We show that dramatic change in the plasma spectrum is caused by strain-induced redistribution of charge carriers between anisotropic $X_x$ and $X_y$ valleys. Discovered piezoplasmonic effect provides a tool to study the band structure of 2D systems. We use piezoplasmonic effect to measure how the inter-valley energy splitting depends on the deformation. This dependency yields the AlAs deformation potential of $E_2 = (5.6 pm 0.3)$~eV.
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Terahertz photoconductivity of $100~mu$m and $20~mu$m Hall bars fabricated from narrow AlAs quantum wells (QWs) of different widths is investigated in this paper. The photoresponse is dominated by collective magnetoplasmon excitations within the body of the Hall structure. We observed a radical change of magnetoplasma spectrum measured precisely for AlAs QWs of width ranging from $4$~nm up to $15$~nm. We have shown that the observed behavior is a vivid manifestation of valley transition taking place in the two-dimensional electron system. Remarkably, we show that photoresponse for AlAs QWs of width $6$~nm features two resonances, indicating simultaneous occupation of strongly anisotropic $X_{x-y}$ valleys and isotropic $X_z$ valley in the QW plane. Our results pave the way to realizing valley-selective layered heterostructures, with potential application in valleytronics.
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