Spin-orbit field switching of magnetization in ferromagnetic films with perpendicular anisotropy

As an alternative to conventional magnetic field, the effective spin-orbit field in transition metals, derived from the Rashba field experienced by itinerant electrons confined in a spatial inversion asymmetric plane through the s-d exchange interaction, is proposed for the manipulation of magnetization. Magnetization switching in ferromagnetic thin films with perpendicular magnetocrystalline anisotropy can be achieved by current induced spin-orbit field, with small in-plane applied magnetic field. Spin-orbit field induced by current pulses as short as 10 ps can initiate ultrafast magnetization switching effectively, with experimentally achievable current densities. The whole switching process completes in about 100 ps.Comment: 4 pages, 3 figure

Magnetoplasmons excitations in graphene for filling factors ν≤6\nu \leq 6

In the frame of the Hartree-Fock approximation, the dispersion of magnetoplasmons in Graphene is derived for all types of transitions for filling factors $\nu\leq 6$. The optical conductivity components of the magnetoplasmon curves are calculated. It is shown that the electron-electron interactions lead to a strong re-normalization of the apparent Fermi velocity of Graphene which is different for different types of transitions.Comment: 15 pages, 7 figure

Double-exciton component of the cyclotron spin-flip mode in a quantum Hall ferromagnet

We report on the calculation of the cyclotron spin-flip excitation (CSFE) in a spin-polarized quantum Hall system at unit filling. This mode has a double-exciton component which contributes to the CSFE correlation energy but can not be found by means of a mean field approach. The result is compared with available experimental data.Comment: 9 pages, 2 figure

Evidence for magnetoplasmon character of the cyclotron resonance response of a two-dimensional electron gas

Experimental results on the absolute magneto-transmission of a series of high density, high mobility GaAs quantum wells are compared with the predictions of a recent magnetoplasmon theory for values of the filling factor above 2. We show that the magnetoplasmon picture can explain the non-linear features observed in the magnetic field evolution of the cyclotron resonance energies and of the absorption oscillator strength. This provides experimental evidence that inter Landau level excitations probed by infrared spectroscopy need to be considered as many body excitations in terms of magnetoplasmons: this is especially true when interpreting the oscillator strengths of the cyclotron transitions

Harper-Hofstadter problem for 2D electron gas with k{\bf k}-linear Rashba spin-orbit coupling

The Harper-Hofstadter problem for two-dimensional electron gas with Rashba spin-orbit coupling subject to periodic potential and perpendicular magnetic field is studied analytically and numerically. The butterfly-like energy spectrum, spinor wave functions as well as the spin density and average spin polarization are calculated for actual parameters of semiconductor structure. Our calculations show that in two-dimensional electron gas subject to periodic potential and uniform magnetic field the effects of energy spectrum splitting caused by large spin-orbit Rashba coupling can be observed experimentally.Comment: 8 pages, 6 figures. submitted to Europhys. Letter

Spin-Orbit Coupling and Tunneling Current in a Parabolic Quantum Dot

We propose a novel approach to explore the properties of a quantum dot in the presence of the spin-orbit interaction and in a tilted magnetic field. The spin-orbit coupling within the quantum dot manifest itself as anti-crossing of the energy levels when the tilt angle is varied. The anti-crossing gap has a non-monotonic dependence on the magnitude of the magnetic field and exhibits a peak at some finite values of the magnetic field. From the dependence of the tunneling current through the quantum dot on the bias voltage and the tilt angle, the anti-crossing gap and most importantly the spin-orbit strength can be uniquely determined

Interacting fermions in two dimensions: beyond the perturbation theory

We consider a system of 2D fermions with short-range interaction. A straightforward perturbation theory is shown to be ill-defined even for an infinitesimally weak interaction, as the perturbative series for the self-energy diverges near the mass shell. We show that the divergences result from the interaction of fermions with the zero-sound collective mode. By re-summing the most divergent diagrams, we obtain a closed form of the self-energy near the mass shell. The spectral function exhibits a threshold feature at the onset of the emission of the zero-sound waves. We also show that the interaction with the zero sound does not affect a non-analytic, $T^{2}$-part of the specific heat.Comment: 5 pages, 4 figure

Rashba interaction in quantum wires with in-plane magnetic fields

We analyze the spectral and transport properties of ballistic quasi one-dimensional systems in the presence of spin-orbit coupling and in-plane agnetic fields. Our results demonstrate that Rashba precession and intersubband coupling must be treated on equal footing for wavevectors near the magnetic field induced gaps. We find that intersubband coupling limits the occurrence of negative effective masses at the gap edges and modifies the linear conductance curves in the strong coupling limit. The effect of the magnetic field on the spin textured orientation of the wire magnetization is discussed.Comment: 6 pages, 6 figures; new figures, discussion extende

Robustness of Majorana Modes and Minigaps in a Spin-Orbit-Coupled Semiconductor-Superconductor Heterostructure

We study the robustness of Majorana zero energy modes and minigaps of quasiparticle excitations in a vortex by numerically solving Bogoliubov-deGennes equations in a heterostructure composed of an \textit{s} -wave superconductor, a spin-orbit-coupled semiconductor thin film, and a magnetic insulator. This heterostructure was proposed recently as a platform for observing non-Abelian statistics and performing topological quantum computation. The dependence of the Majorana zero energy states and the minigaps on various physics parameters (Zeeman field, chemical potential, spin-orbit coupling strength) is characterized. We find the minigaps depend strongly on the spin-orbit coupling strength. In certain parameter region, the minigaps are linearly proportional to the \textit{s}-wave superconducting pairing gap $\Delta_{s}$, which is very different from the $\Delta_{s}^{2}$ dependence in a regular \textit{s-} or \textit{\p}-wave superconductor. We characterize the zero energy chiral edge state at the boundary and calculate the STM signal in the vortex core that shows a pronounced zero energy peak. We show that the Majorana zero energy states are robust in the presence of various types of impurities. We find the existence of impurity potential may increase the minigaps and thus benefit topological quantum computation.Comment: 11 pages, 15 figure