Effects of the reduction of the dimension of a system upon spin ordering in a degenerate electron gas
- PDF / 207,472 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 26 Downloads / 152 Views
C PROPERTIES OF SOLID
Effects of the Reduction of the Dimension of a System upon Spin Ordering in a Degenerate Electron Gas F. E. Orlenkoa,*, S. I. Chelkaka, E. V. Orlenkoa,**, and G. G. Zegryab a
St. Petersburg State Polytechnic University, Politekhnicheskaya ul. 29, St. Petersburg, 195251 Russia * email: [email protected] ** email: [email protected] b Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021 Russia Received August 27, 2009
Abstract—Collective effects of spin ordering in a quasionedimensional degenerate electron gas are dis cussed. The total energy of the quasionedimensional system, as well as the exchange contribution per par ticle, has been calculated by the Hartree–Fock method. It has been shown that spontaneous polarization can be observed in the system when a universal parameter related to the density of the particles satisfies the ine quality rs ≥ 0.476. A comparative analysis of one, two, and threedimensional systems has been performed. A general expression has been obtained for the total energy per particle as a function of the degree of polar ization and dimension of the system. According to this expression, the possibility of spontaneous polarization in the system is closely correlated with the dimension of the system. DOI: 10.1134/S1063776110050110
1. INTRODUCTION A system of electrons or holes whose motion is free only in one spatial dimension and their motion in the second and third dimensions correspond to a discrete energy spectrum is called the dynamic onedimen sional (or quasionedimensional) system. Thus, only one of the three components of the wave vector is a good quantum number. We emphasize that such a sys tem is not onedimensional in the direct meaning, because the wavefunction of carriers is a function of three coordinates and electromagnetic fields propa gate in threedimensional space. For this reason, the theoretical predictions valid for ideally onedimen sional systems should be correspondingly changed before comparing them with the experimental data. The quasionedimensional system can be experi mentally obtained, e.g., on the (114) surface of the bis muth semimetal on which quasionedimensional properties of the electron gas [1] in the socalled topo logical metal are maintained. In this case, the contour of the Fourier surface is experimentally observed. The static and transport properties of the onedimensional electron system in a periodic potential are determined by three competing contributions [2]. The first contribution is associated with the uncer tainty principle and the character of the filling of quantum states: such a system has no pronounced Fermi “surface” [3, 4], its boundary is always spread; this property is less pronounced in systems of higher dimensions. The second contribution comes from the exchange interaction depending on the spin state of the interact
ing particles (the Pauli exclusion principle). Owing to the interparticle interaction, the system behaves as an el
Data Loading...
