Tailoring Spin Textures in Non-centrosymmetric Systems

In non-centrosymmetric systems, the non-vanishing gradient of the electrostatic potential results in a momentum dependent magnetic field in the rest frame of the electrons. The coupling of this field with the spin of the electron lifts the spin-degeneracy of the bands in an otherwise non-magnetic system and also leads to complex spin textures in the reciprocal space. Spin textures depending on the symmetry may display Rashba, Dresselhaus, persistent or more complex spin configurations that are important for spintronics application. We show a class of polar non-centrosymmetric ferroelectric systems have all the necessary ingredients to host Rashba-Dresselhaus effect. We shall argue in addition to crystal symmetry, the orbital character of the bands at a particular k-point and the associated symmetry plays a crucial role in in stabilizing persistent spin texture (PST) in these systems. Finally we show a class of non-polar half-Heusler alloys with rich local symmetry of the wavevectors display Dresselhaus effect, Rashba effect with both linear and non-linear terms, non-trivial Zeeman spin splitting and band splitting with vanishing spin polarization making them ideal candidate for application in spin valleytronics.