Collapse of ${\rho }_{xx}$ ringlike structures in 2DEGs under tilted magnetic fields

Abstract

In the quantum Hall regime, the longitudinal resistivity ${\rho }_{xx}$ plotted as a density--magnetic-field ($n_{2D}-B$) diagram displays ringlike structures due to the crossings of two sets of spin split Landau levels from different subbands [e.g., Zhang \textit{et al.}, Phys. Rev. Lett. \textbf{95}, 216801 (2005)]. For tilted magnetic fields, some of these ringlike structures "shrink" as the tilt angle is increased and fully collapse at ${\theta }_c\approx 6^{\circ }$. Here we theoretically investigate the topology of these structures via a non-interacting model for the 2DEG. We account for the inter Landau-level coupling induced by the tilted magnetic field via perturbation theory. This coupling results in anti-crossings of Landau levels with parallel spins. With the new energy spectrum, we calculate the corresponding $n_{2D}-B$ diagram of the density of states (DOS) near the Fermi level. We argue that the DOS displays the same topology as ${\rho }_{xx}$ in the $n_{2D}-B$ diagram. For the ring with filling factor $\nu =4$, we find that the anti-crossings make it shrink for increasing tilt angles and collapse at a large enough angle. Using effective parameters to fit the $\theta =0^{\circ }$ data, we find a collapsing angle ${\theta }_c\approx 3.6^{\circ }$. Despite this factor-of-two discrepancy with the experimental data, our model captures the essential mechanism underlying the ring collapse.

arXiv comment3 pages, 2 figures; Proceedings of the PASPS V Conference Held in August 2008 in Foz do Iguaçu, Brazil

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Cited by in corpus (3)

• Many-body effects on the ${\rho }_{xx}$ ringlike structures in two-subband wells
• Persistent spin splitting of a two-dimensional electron gas in tilted magnetic fields
• Quenching of the DOS beats in a two-dimensional electron gas in tilted magnetic fields