Abrupt enhancement of spin–orbit scattering time in ultrathin semimetallic SrIrO3 close to the metal–insulator transition

Abstract

We report a magnetotransport study of spin relaxation in 1.4–21.2 nm epitaxial SrIrO3 thin films coherently strained on SrTiO3 substrates. Fully charge compensated semimetallic transport has been observed in SrIrO3 films thicker than 1.6 nm, where the charge mobility at 10 K increases from 45 cm2/V s to 150 cm2/V s with decreasing film thickness. In the two-dimensional regime, the charge dephasing and spin–orbit scattering lengths extracted from the weak localization/anti-localization effects show power-law dependence on temperature, pointing to the important role of electron–electron interaction. The spin–orbit scattering time τso exhibits an Elliott–Yafet mechanism dominated quasi-linear dependence on the momentum relaxation time τp. Ultrathin films approaching the critical thickness of metal–insulator transition show an abrupt enhancement in τso, with the corresponding τso/τp about 7.6 times of the value for thicker films. A likely origin for such unusual enhancement is the onset of strong electron correlation, which leads to charge gap formation and suppresses spin scattering.

Evidence of weak antilocalization in quantum interference effects of (001) oriented La0.7Sr0.3MnO3–SrRuO3 superlattices

“…As the LSMO thickness increases, Δσ(H) of the [20 u:c: SRO/5 u:c: LSMO] Â15 superlattice shows a transition from WL to WAL with the increasing field. However, similar Δσ(H) has been observed in the SrIrO 3 grown on STO40 and LaAlO 3 //SrTiO 3 /LaAlO 3 heterostructure,41 which is explained by the modification of weak localization by spin-orbit coupling. The positive MR of the [20 u:c: SRO/3 u:c: LSMO] Â15 superlattice is attributed to spin-orbit coupling associated with magnetic anisotropy, i.e., spin and bond length fluctuation 42,43.…”

Epitaxial NiCo2O4 film as an emergent spintronic material: Magnetism and transport properties

“…As shown in Fig. 5(a), the easy axis is along the out-of-plane [001] direction, while the in-plane [100] direction becomes a hard axis.…”

“…Defining the energy integral 𝐼 𝑀𝑑𝐻 , where H, H sat , and M are the magnetic field, saturation magnetic field for the hard axis, and magnetization, respetively, the free energy different between the inplane [100] direction and out-of-plane [001] direction can be calculated as 𝐸 𝐼 𝐼 , which is equal to 𝐹 𝑥 𝐹 𝑧̂ 𝐵 𝑒 𝑒 ). This mean that 𝐵 .…”

“…As shown in Fig. 5(d), as 𝐵 < 0, the compressive strain increases the energy along the [100] and [010] directions, making them the hard axes. Meanwhile, the energy along the [001] direction is reduced, making it a global easy axis.…”

Oxidic 2D Materials

“…Research into new physical and chemical properties as well as the development of functional applications is also possible by combining two layers to form heterostructured bilayers. The large amount of newly accessible properties creates entirely new application potentials and motivated initial investigations of thin film phenomena and considerations of their practical implementation [3,225,226].…”