Mass-asymmetry effects in coupled electron-hole quantum wire system

• Published in: The European physical journal. B, Condensed matter physics Condensed matter physics, 2010-04, Vol.74 (4), p.517-525
• Main Authors: Moudgil, R. K., Garg, Vinayak, Ahluwalia, P. K.
• Format: Article
• Language: English
• Subjects: Complex Systems; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electrons; Exact sciences and technology; Fluid- and Aerodynamics; Mesoscopic and Nanoscale Systems; Physics; Physics and Astronomy; Quantum wires; Solid State Physics; Toy industry
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2010-00103-9

The effect of mass-asymmetry on the ground-state of coupled electron-hole quantum wire system is investigated within the quantum version of the self-consistent mean-field approximation of Singwi, Tosi, Land, and Sjölander. The pair-correlation functions, static density susceptibility, and correlation energy are calculated over a range of wire parameters. We find that the mass-asymmetry affects appreciably both the intra- and inter-wire correlations, which in turn bring in a marked change in the e-h ground-state. Below a critical density, the e-h correlations now favor the liquid-Wigner crystal phase transition at a sufficiently large wire spacing. This result is in striking difference with the corresponding study on the mass-symmetric e-h wire model since here transition to the Wigner crystal phase occurs in the adequately close proximity of two wires at a much lower density, and there also occurs a crossover from Wigner to a charge-density-wave phase at relatively higher densities. We find that for a GaAs based e-h wire the critical density for Wigner crystallization is enhanced by a factor of about 2.6. As an important result, our theory captures nicely the recent experimental observation of Wigner crystallization in an un-equal density GaAs based e-h wire by Steinberg et al. [Phys. Rev. B 73 , 113307 (2006)].