Quenching of the DOS beats in a two-dimensional electron gas in tilted magnetic fields

Abstract

A two-dimensional electron gas exposed to a tilted magnetic field is considered with the Rashba spin-orbit interaction and the Zeeman effect. An exact solution for the eigenvalues was obtained assuming that two opposite spin states of adjacent Landau levels have equal probability. No crossings between adjacent eigenenergies were observed, for the tilt angles studied here (θ ≤ 80 • ), unlike in the perpendicular-magnetic-field case. The absence of crossings lead to quenched beating structures in the oscillations of the density of states (DOS). Persistent spin-splittings were observed at the weak magnetic field region. The splittings, however, can be effectively screened by an increased Landau level broadening. The results shed light on how spins can be controlled through the Rashba interaction strength, the disorder-related broadening and the magnetic field tilt angle.

Two-dimensional electron gas tilt-induced Landau level crossings

“…Moreover, only at these regions did we also observe the crossings which is indicative of beats and crossings being concomitant. Since the beats are due to the spin splitting induced by the Rashba SOI and crossings are found in the case of zero tilt [4,22] but are not found for θ < 80 • [4], we deduce that the magnetic field's tilt relative to the 2DEG plane shifts the spin splitting-induced crossings to large angles as observed in this paper.…”

“…Not only is the Rashba SOI linked with the beats in these Shubnikov-de Haas (SdH) oscillations but it also gives way to a direction-dependent energy spectrum [15]. The authors of this present paper have previously shown that when both Rashba and Zeeman interactions are taken into account there are no beating patterns in the density of states of the 2DEG for θ ≤ 80 • [4]. The authors observed that depending on the intensity of the applied magnetic field B, the Rashba SOI and Zeeman term signatures can be distinguished [5].…”

“…Collating all of the abovementioned observations, beats are found at the two ends of the tilt spectrum -the zero tilt (B = 0) [4] and the large tilt (B → B). In between these two extremities, the beats are not observed.…”

“…The Hamiltonian above is exactly solvable when B is normal to the 2DEG. However, if a finite in-plane component, B = B sin(θ), is present, the problem becomes underspecified and an analytic solution can only be achieved when additional specifications are imposed [4,20]. We circumvent the underspecified problem by imposing equal probability among pairs of LLs that are known to cross when B = 0 [4,5].…”

Integer effects in the entanglement and spin fluctuations of a quantum Hall system with Rashba interactions

“…The density of delocalized states thus remains sharp about the band centers, which causes several thermodynamic and transport quantities of the 2D electron gas to exhibit pronounced changes as the Fermi level jumps discontinuously between delocalized band gaps [20][21][22][23][24][25]. Indeed, experimental observations of the Shubnikov-de Haas effect and de Haas-van Alphen effect have been used to obtain the value of the Rashba parameter [21,24,[26][27][28][29][30][31][32][33][34][35]. The second objective of this work is to show that similar integer effects exist in the total spinorbit entanglement entropy originating from the Rashba interaction (section 3).…”