Spin interferometry in anisotropic spin-orbit fields

Abstract

Electron spins in a two-dimensional electron gas (2DEG) can be manipulated by spin-orbit (SO) fields originating from either Rashba or Dresselhaus interactions with independent isotropic characteristics. Together, though, they produce anisotropic SO fields with consequences on quantum transport through spin interference. Here we study the transport properties of modelled mesoscopic rings subject to Rashba and Dresselhaus [001] SO couplings in the presence of an additional inplane Zeeman field acting as a probe. By means of 1D and 2D quantum transport simulations we show that this setting presents anisotropies in the quantum resistance as a function of the Zeeman field direction. Moreover, the anisotropic resistance can be tuned by the Rashba strength up to the point to invert its response to the Zeeman field. We also find that a topological transition in the field texture that is associated with a geometric phase switching is imprinted in the anisotropy pattern. We conclude that resistance anisotropy measurements can reveal signatures of SO textures and geometric phases in spin carriers.

Photovoltaic effect generated by spin-orbit interactions

“…This coupling obeys time-reversal symmetry which prevents spin splitting of electron transport in two-terminal junctions [7], in most cases eliminating the possibility to manipulate electronic conduction through Rashba weak links. Spin-orbit interactions do, however, have an effect on spin-polarized electrons in magnetic materials [8][9][10], and on electrons subjected to external magnetic fields [11][12][13][14][15][16]. Here we propose that imposing a time dependence on the effective magnetic fields induced by the spin-orbit coupling offers another means to destroy time-reversal symmetry of twoterminal junctions.…”

“…The equal-time lesser Green's function on the dot, as given on the main text, is obtained by setting t = t in Eq. (14), and using Eqs. (12) in conjunction with the expressions for the self energy given in the main text.…”

DC spin generation by junctions with AC driven spin-orbit interaction

“…Indeed, as seen in Eqs. (15) and (17) below for the spin polarization in the left lead, interchanging L with R in each of them to obtain the spin polarization in the right one leaves them intact,Ṁ L (t) =Ṁ R (t); the total spin is not conserved, and the junction injects the same amount of spin polarization into the two leads, even in the absence of any bias voltage. From Eqs.…”

“…For this two-terminal case, the time-independent SOI that obeys time-reversal symmetry cannot generate spin splitting. 12 Time-reversal symmetry can be broken by applying a magnetic field, either via a magnetic flux, which penetrates SOI-active loops of Aharonov-Bohm interferometers, [13][14][15] or by a Zeeman magnetic field. 16,17 Alternatives utilize ferromagnetic terminals.…”

Electric and magnetic gating of Rashba-active weak links

“…Timereversal symmetry is broken by applying a magnetic field. Indeed, several proposed devices utilize an orbital Aharonov-Bohm magnetic flux, which penetrates loops of interferometers to achieve spin splitting [13][14][15], via the interference of the spinor wave functions in the two branches of the loop.…”