2D Electronic Transport with Strong Spin-Orbit Coupling in Bi(2-) Square Net of Y2O2Bi Thin Film Grown by Multilayer Solid-Phase Epitaxy

Superconductivity and improved electrical conduction in anti-ThCr2Si2-type RE 2O2Sb and RE 2O2Bi with pnictogen square net

Layered compounds have shown rich physical properties such as high-temperature superconductivity. Recently, monatomic honeycomb lattice systems, such as graphene, have been studied extensively, whereas monatomic pnictogen square nets in layered compounds also exhibit interesting electronic properties owing to their unusual negative valence states. Among them, anti-ThCr2Si2-type RE 2O2 Pn (RE = rare earth, Pn = Sb, Bi) with monoatomic Pn square nets were recently found to exhibit interesting electronic properties such as superconductivity and high carrier mobility. In this article, we review recent studies on crystal structures, electronic properties, and thin-film growth of RE 2O2 Pn.

“Flat/steep band model” for superconductors containing Bi square nets

The crystal structures of a new family of superconductors containing a Bi square net and their electronic structures around the Fermi level have been reviewed. The structures of these compounds can be viewed as stacked layers denoted by [Bi][(RE)(M 2Bi2)(RE)] RE = rare earth or alkaline earth metal, M = transition metal. Flat/steep band features are shown to exist in all these new superconductors, though the pairing mechanisms may be very different. The Dirac Fermion behavior is reviewed and its implications are discussed.

Mixed-Valence Nickel Bis(azamacrocycle) Compounds with Ghost-Leg-type Sheets

The fabrication of so-called ghost-leg sheets and their electronic properties is reported. This unique sheet structure is composed of one-dimensional mixed-valence nickel chains, which are linked with one another by bis(azamacrocycle) ligands. They are also topologically unique Ni^II /Ni^III mixed-valence complexes, as confirmed by X-ray and optical measurements. Moreover, their magnetic susceptibilities indicated two-dimensional antiferromagnetic behavior following the Fisher 1D chain model with interchain interactions, where spins on Ni^III sites mutually interact antiferromagnetically in the sheets.

Universal modeling of weak antilocalization corrections in quasi-two-dimensional electron systems using predetermined return orbitals

We have developed a method to calculate the weak localization and antilocalization corrections based on the real-space simulation, where we provide 147 885 predetermined return orbitals of quasi-two-dimensional electrons with up to 5000 scattering events that are repeatedly used. Our model subsumes that of Golub [L. E. Golub, Phys. Rev. B 71, 235310 (2005)PRBMDO1098-012110.1103/PhysRevB.71.235310] when the Rashba spin-orbit interaction (SOI) is assumed. Our computation is very simple, fast, and versatile, where the numerical results, obtained all at once, cover wide ranges of the magnetic field under various one-electron interactions H^{'} exactly. Thus, it has straightforward extensibility to incorporate interactions other than the Rashba SOI, such as the linear and cubic Dresselhaus SOIs, Zeeman effect, and even interactions relevant to the valley and pseudo spin degrees of freedom, which should provide a unique tool to study new classes of materials like emerging 2D materials. Using our computation, we also demonstrate the robustness of a persistent spin helix state against the cubic Dresselhaus SOI.