Persistent spin helix in Rashba-Dresselhaus ferroelectric CsBiNb2O7

Abstract

Ferroelectric Rashba semiconductors (FERSC) are a novel class of multifunctional materials showing a giant Rashba spin splitting which can be reversed by switching the electric polarization. Although they are excellent candidates as channels in spin field effect transistors, the experimental research has been limited so far to semiconducting GeTe, in which ferroelectric switching is often prevented by heavy doping and/or large leakage currents. Here, we report that CsBiNb2O7, a layered perovskite of Dion-Jacobson type, is a robust ferroelectric with sufficiently strong spin-orbit coupling and spin texture reversible by electric field. Moreover, we reveal that its topmost valence band's spin texture is quasi-independent from the momentum, as a result of the low symmetry of its ferroelectric phase. The peculiar spin polarization pattern in the momentum space may yield the so-called "persistent spin helix", a specific spin-wave mode which protects the spin from decoherence in diffusive transport regime, potentially ensuring a very long spin lifetime in this material.

Large spin splittings due to the orbital degree of freedom and spin textures in a ferroelectric nitride perovskite

“…Our models of Eqs. (1) and (2) for the and L points contain some terms that have been previously proposed [4,5,9,13,14,49,50]. Recently, we also became aware of work about Rashba-Dresselhaus spin splittings in LaWN 3 [51].…”

“…Spin splitting in ferroelectric materials is attracting a great deal of attention because it offers the possibility of novel spintronic devices based on electric control of spin textures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Recently, various ferroelectrics presenting large spin splittings have been proposed theoretically or synthesized, including GeTe [6], SnTe [7], hyperferroelectrics [10,12], halides [8], and iodide perovskites [11], and the recently discovered Bi 2 WO 3 [3], BiInO 3 [5], and HfO 2 [9].…”

“…Moreover, most of the observed spin textures, including those for HfO 2 [9] and BiInO 3 [5], are of linear Dresselhaus (spin-splitting parameter denoted by λ D ) or linear Rashba (spin-splitting parameter referred to as λ R ) type, or even a mixture of them by varying the ratio between λ D and λ R . For instance, the persistent spin textures, whose spin configurations do not depend on momentum, have been predicted to occur in BiInO 3 [5], CsBiNb 2 O 7 [13], and other materials [5] (in these cases, λ D and λ R are almost equal in magnitude). On one hand, the spin splittings and textures for most of these systems were well described by a two-band effective Hamiltonian involving only spin degree of freedom (SDF) (i.e., spin up |↑ and spin down |↓ ).…”

Topological Transition in Pb1-xSnxSe using Meta-GGA Exchange-Correlation Functional

“…We look also to the role played by the spin-orbit coupling (SOC) in driving this transition. We stress that SOC is a relativistic effect that may give rise to exotic effects like complex spin texture [34], spin Hall effect [35], topological phases [36], large magnetocrystalline anisotropy [37][38][39], and non collinear phases [40].…”

Discreteness of space from anisotropic spin–orbit interaction

“…Let us consider the minimal Hamiltonian (H R D ) with Rashba and Dresselhaus coupling up to third-order in momentum with all the symmetry allowed terms in the p z = 0 plane [20]…”