The interplay of Landau level broadening and temperature on two-dimensional electron systems

Abstract

This work investigates the influence of low temperature and broadened Landau levels on the thermodynamic properties of twodimensional electron systems. The interplay between these two physical parameters on the magnetic field dependence of the chemical potential, the specific heat and the magnetization is calculated. In the absence of a complete theory that explains the Landau level broadening, experimental and theoretical studies in literature perform different model calculations of this parameter. Here it is presented that different broadening parameters of Gaussian-shaped Landau levels cause width variations in their contributions to interlevel and intralevel excitations. Below a characteristic temperature, the interlevel excitations become negligible. Likewise, at this temperature range, the effect of the Landau level broadening vanishes.

Persistent spin splitting of a two-dimensional electron gas in tilted magnetic fields

“…The contribution of these two terms are taken into account in figure 6 since µ varies with both B and T . Experimental and numerical data show that a 2DEG under a perpendicular B has a C V that oscillates as a function of B with the dips coinciding with integer ν [13,15,20,22,24]. These minima coinciding with integer ν are also demonstrated in figure 6.…”

“…Finally, when B is strong, wide and tall peaks emerge with a sharp dip that cuts through each peak. The shape of the C V (B) at region III resembles that of the spinless case [22]. The Zeeman term in this region, creates an additional dip in the previously spin-degenerate Landau levels.…”

“…When only the cyclotron energy E c is considered, that is, spin is neglected, µ peaks are large only for even ν [22,23,24]. The presence of odd ν peaks for all B region in figure 1, for example, is evidence of a substantial spin splitting.…”

The Intrinsic Features of the Specific Heat at Half-Filled Landau Levels of Two-Dimensional Electron Systems

“…3.1 For a Delta-shaped DOS As shown in the numerical calculations of Ref. [15] at constant N , despite the presence of the broadening of Landau levels, a characteristic low temperature is reached at which the 2DEG approaches its ideal electron gas behavior. Therefore, the continued use of a delta-shaped DOS is justified in heat capacity measurements at strong B and below a characteristic low T .…”

“…using the root-finding method as outlined in Ref. [15]. Here f (E) is the Fermi-Dirac distribution function and it is given as…”