Spin-orbit effects in ferroelectric PbTiO3 under tensile strain

Abstract

We report a study based on first-principles calculations complemented by a tight-binding approach and a k • p model of the spin-orbit effects in epitaxially strained PbTiO 3 . The imposed biaxial tensile strain allows us to rotate the electrical polarization of PbTiO 3 from out-of-plane to in-plane directions through structural phase transitions between a tetragonal, monoclinic, and orthorhombic phase. It is found that Ti d-state conduction bands exhibit two strong Rashba-like spin-splitting parameters of (1) 0.39 eV Å at a tensile strain η = 1.55% due to a polarization rotation in the monoclinic phase and (2) 1.08 eV Å under large tensile strain of 3.8% due to band anticrossing in the orthorhombic phase. Remarkably, we also identified the presence of a quasipersistent spin texture for the band with a d yz−zx character in the orthorhombic phase. We then conclude that using strain could be an interesting way to tune the spin-orbit effects in ferroelectric materials with technological interests.

Interplay of domain structure and phase transitions: theory, experiment and functionality

“…Effective Hamiltonian and second principles methods are based on the idea to reduce the number of degrees of freedom for the system under study while keeping an approximate description of physical properties of interest like the electronic or magnetic structures. This concept of coarse graining has been successfully used for decades in tight-binding models [188][189][190]. One class of simple and extensively used coarsegrained models for ferroic phase transitions are spin lattice models such as the Ising model.…”

Rashba spin splitting and anomalous spin textures in the bulk ferroelectric oxide perovskite KIO3

“…This can be done by calculating the total formation energy of structures with different space groups as a function of strain to know which one is the most stable at a particular strain. 61 The spin degeneracy can be restored when the structure is brought back to the parent centrosymmetric structure. The parent space group of R3m is R 3m, which is generated by the symmetry elements of R3m followed by an inversion.…”

Rashba splitting in polar-nonpolar sandwich heterostructure: a DFT study

“…The field of spin-orbitronics started with semiconductors [26] and metals [27]. Later on it expanded its domain in the non-centrosymmetric bulk oxides, such as BiAlO 3 [28], KTaO 3 [29], KIO 3 [30], PbTiO 3 [31]. Although the evidence of RSOC has been found in these bulk systems, the inherent requirement of ferroelectricity severely restricts the number of such materials.…”