Interplay of spin–orbit coupling and Coulomb interaction in ZnO-based electron system

Abstract

Spin–orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron–electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron–electron interactions can modify this coupling. Here we demonstrate the emergence of the SOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system also features strong electron–electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron–electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density.

Origin and properties of an unexpected exchange bias of Ta/Ni80Fe20/Ir20Mn80/Ta heterostructure in ultrathin limit: Impact of the oblique deposition and Ta/Ni80Fe20 alloying

“…1) and by using the previous formula, the value of the effective anisotropy constant = (1.1 ± 0.5) x 10 4 J/m 3 is calculated. Since the in-plane effective anisotropy energy has the uniaxial form and the magnetization is in the sample plane, the following relation is valid: (6) where is defined in the introduction part. The contribution of the fcc K MA anisotropy (≈ -2.7 × 10 2 J/m 3 for Py) [28,32,33] and other minority terms to are too low and are not considered in Eq.…”

“…The magnetocrystalline anisotropy (K MA ) results from the electric interaction between the non-spherical charge orbital, responsible for the orbital magnetic moment of the atom, and the crystal field created by the ions of the crystalline lattice. It favors the alignment of magnetization in specific directions of the crystal lattice due to the spin-orbit coupling [6,7]. Another important anisotropy is the shape anisotropy (K SH ), which depends on the sample geometry.…”

Interplay between exchange split Dirac and Rashba-type surface states in MnBi$_2$Te$_4$/BiTeI interface

“…The same has been previously observed under additional surface doping [39] when the surface negative charge reduces the exchange gap in pristine MBT [39], due to downshift of the upper part of the split Dirac cone. Such relationship of spin-orbit interaction and electric field effects has been revealed in various materials [44][45][46].…”

Piezoelectric manipulation of spin–orbit coupling in a Wurtzite heterostructure

“…Piezoelectricity, which uses strain to generate electrical polarization, manifests itself by combining the electric field triggered by polarization discontinuity at the interface with a deformation potential, which relies on strain, to control the electronic band structures. Based on this principle, the combination of piezoelectricity and SOC effects render wurtzite heterostructures as ideal testbeds not only to steer exotic physics, including topological phase transition, 7,8 spin transport, 9,10 electron-electron interaction, 11,12 and Landau level crossing 13 but also to improve the device performance in piezotronics and piezo-phototronic transistors. 10,14,15 In wurtzite heterostructures with inherent (spontaneous or lattice-misfit strain-induced piezoelectric) polarization, several approaches have been reported for SOC modulation, including electric field, 16,17 magnetic field, 18 alloy content, 11 geometrical form and interfacial effect.…”

“…Based on this principle, the combination of piezoelectricity and SOC effects render wurtzite heterostructures as ideal testbeds not only to steer exotic physics, including topological phase transition, 7,8 spin transport, 9,10 electron-electron interaction, 11,12 and Landau level crossing 13 but also to improve the device performance in piezotronics and piezo-phototronic transistors. 10,14,15 In wurtzite heterostructures with inherent (spontaneous or lattice-misfit strain-induced piezoelectric) polarization, several approaches have been reported for SOC modulation, including electric field, 16,17 magnetic field, 18 alloy content, 11 geometrical form and interfacial effect. 19,20 However, so far, very little attention has been paid to pure piezoelectric manipulation of SOC, particularly with piezoelectricity driven by external stimulus, which has been known as an intriguing strategy for operating electronics and optoelectronic sensing devices, 21,22 and most importantly, which shows the perspective for flexible spintronic applications.…”