Diffusion Monte Carlo study of excitons and biexcitons in a mass-asymmetric electron–hole bilayer

Sharma, Rajesh O.; Saini, L. K.; Bahuguna, Bhagwati Prasad

doi:10.1039/c7cp02934a

Cited by 3 publications

(3 citation statements)

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“…Two-dimensional systems of coupled, parallel quantum layers (electron-electron or electron-hole bilayers) show many unique phenomena [26][27][28][29][30][31][32]. Similarly, in 1D systems the additional interaction between charge carriers residing in different wires yields quantum properties such * sharmarajesh0387@gmail.com as non-Abelian topological phases (edge properties) [33][34][35][36][37], Coulomb drag between wires [38][39][40], nonadditive dispersion [41][42][43][44], enhancement in the onset of Wigner crystallization [45], and formation of biexcitons [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Ground-state properties of electron-electron biwire systems

et al. 2021

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The correlation between electrons in different quantum wires is expected to affect the electronic properties of quantum electron-electron biwire systems. Here, we use the variational Monte Carlo method to study the ground-state properties of parallel, infinitely thin electron-electron biwires for several electron densities (rs) and interwire separations (d). Specifically, the ground-state energy, the correlation energy, the interaction energy, the pair-correlation function (PCF), the static structure factor (SSF), and the momentum distribution (MD) function are calculated. We find that the interaction energy increases as ln(d) for d → 0 and it decreases as d −2 when d → ∞. The PCF shows oscillatory behavior at all densities considered here. As two parallel wires approach each other, interwire correlations increase while intrawire correlations decrease as evidenced by the behavior of the PCF, SSF, and MD. The system evolves from two monowires of density parameter rs to a single monowire of density parameter rs/2 as d is reduced from infinity to zero. The MD reveals Tomonaga-Luttinger (TL) liquid behavior with a power-law nature near kF even in the presence of an extra interwire interaction between the electrons in biwire systems. It is observed that when d is reduced the MD decreases for k < kF and increases for k > kF, similar to its behavior with increasing rs. The TL liquid exponent is extracted by fitting the MD data near kF, from which the TL liquid interaction parameter Kρ is calculated. The value of the TL parameter is found to be in agreement with that of a single wire for large separation between the two wires.

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Section: Introductionmentioning

confidence: 99%

Ground-state properties of electron-electron biwire systems

et al. 2021

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“…On the other hand, at sufficiently small inter-layer distances, the Coulomb attraction between the electrons and holes becomes strong, and as a result the electron and hole may bind together to form an exciton. If the separation d is very small, then exctions may bind together to form biexcitons [25][26][27]. Eventually, when d reduces to 0, tunnelling of particles between the layers sets in, due to which the bilayer system should again show the properties of a single-layer system.…”

Section: Resultsmentioning

confidence: 99%

“…Other phases are possible, such as the biexciton and CDW phases, which are not included here to reduce the computational complexity. We have also not considered the mass asymmetric case [26][27][28][29] because it is important to understand the underlying physics of simple systems before moving onto more realistic but more complicated systems. The rest of this paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Phase diagram of a symmetric electron–hole bilayer system: a variational Monte Carlo study

Sharma

Saini²,

Bahuguna³

2018

J. Phys.: Condens. Matter

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We study the phase diagram of a symmetric electron-hole bilayer system at absolute zero temperature and in zero magnetic field within the quantum Monte Carlo approach. In particular, we conduct variational Monte Carlo simulations for various phases, i.e. the paramagnetic fluid phase, the ferromagnetic fluid phase, the anti-ferromagnetic Wigner crystal phase, the ferromagnetic Wigner crystal phase and the excitonic phase, to estimate the ground-state energy at different values of in-layer density and inter-layer spacing. Slater-Jastrow style trial wave functions, with single-particle orbitals appropriate for different phases, are used to construct the phase diagram in the (r , d) plane by finding the relative stability of trial wave functions. At very small layer separations, we find that the fluid phases are stable, with the paramagnetic fluid phase being particularly stable at [Formula: see text] and the ferromagnetic fluid phase being particularly stable at [Formula: see text]. As the layer spacing increases, we first find that there is a phase transition from the ferromagnetic fluid phase to the ferromagnetic Wigner crystal phase when d reaches 0.4 a.u. at r = 20, and before there is a return to the ferromagnetic fluid phase when d approaches 1 a.u. However, for r < 20 and [Formula: see text] a.u., the excitonic phase is found to be stable. We do not find that the anti-ferromagnetic Wigner crystal is stable over the considered range of r and d. We also find that as r increases, the critical layer separations for Wigner crystallization increase.

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