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Media type:
E-Article
Title:
Fluence dependent dynamics of excitons in monolayer MoSi2Z4 (Z = pnictogen)
Contributor:
Yadav, Pushpendra;
Khamari, Bramhachari;
Singh, Bahadur;
Adarsh, K V;
Agarwal, Amit
imprint:
IOP Publishing, 2023
Published in:Journal of Physics: Condensed Matter
Language:
Not determined
DOI:
10.1088/1361-648x/acc43f
ISSN:
0953-8984;
1361-648X
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title>
<jats:p>Reduced dielectric screening in two-dimensional materials enables bound excitons, which modifies their optical absorption and optoelectronic response. Here, we demonstrate the existence of excitons in the bandgap of the monolayer family of the newly discovered synthetic <jats:inline-formula>
<jats:tex-math><?CDATA $\mathrm{MoSi}_{2}{\mathrm{Z}}_{4}$?></jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msub>
<mml:mrow>
<mml:mi mathvariant="normal">M</mml:mi>
<mml:mi mathvariant="normal">o</mml:mi>
<mml:mi mathvariant="normal">S</mml:mi>
<mml:mi mathvariant="normal">i</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mn>2</mml:mn>
</mml:mrow>
</mml:msub>
<mml:msub>
<mml:mrow>
<mml:mrow>
<mml:mi mathvariant="normal">Z</mml:mi>
</mml:mrow>
</mml:mrow>
<mml:mrow>
<mml:mn>4</mml:mn>
</mml:mrow>
</mml:msub>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacc43fieqn1.gif" xlink:type="simple" />
</jats:inline-formula> (Z=N, P, and As) series of materials. All three monolayers support several bright and strongly bound excitons with binding energies varying from 1 eV to 1.35 eV for the lowest energy exciton resonances. We show that on increasing the pump fluence or photo-excited carrier density, the lowest energy exciton first undergoes a redshift followed by a blueshift, due to the renormalized exciton binding energies. The exciton binding energy varies as a Lennard-Jones-like potential as a function of the inter-exciton spacing. This establishes an atom-like attractive and repulsive interaction between excitons depending on the inter-exciton separation. Our study shows that the <jats:inline-formula>
<jats:tex-math><?CDATA $\mathrm{MoSi}_{2}{\mathrm{Z}}_{4}$?></jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msub>
<mml:mrow>
<mml:mi mathvariant="normal">M</mml:mi>
<mml:mi mathvariant="normal">o</mml:mi>
<mml:mi mathvariant="normal">S</mml:mi>
<mml:mi mathvariant="normal">i</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mn>2</mml:mn>
</mml:mrow>
</mml:msub>
<mml:msub>
<mml:mrow>
<mml:mrow>
<mml:mi mathvariant="normal">Z</mml:mi>
</mml:mrow>
</mml:mrow>
<mml:mrow>
<mml:mn>4</mml:mn>
</mml:mrow>
</mml:msub>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacc43fieqn2.gif" xlink:type="simple" />
</jats:inline-formula> series of monolayers offer an exciting test-bed for exploring the physics of strongly bound excitons and their non-equilibrium dynamics.</jats:p>