Influence of the substrate on the spin-orbit splitting in surface alloys on (111) noble-metal surfaces

Abstract

We have studied by angle-resolved photoelectron spectroscopy the ordered XCu 2 surface alloys formed by X = Sb and Bi on a Cu͑111͒ substrate. We found clear analogies with the corresponding XAg 2 alloys formed by the same elements on Ag͑111͒. The electronic states near the Fermi level are similarly split by the spin-orbit ͑SO͒ interaction with the smaller splitting in XCu 2 reflecting the smaller atomic SO parameter of Cu vs Ag. The charge transfer from the Bi and Sb adatoms to the substrate atoms and their outward relaxation are different for two substrates; both determine the Fermi energy of the two-dimensional electron gas.

Bulk and surface band structure of the new family of semiconductors BiTeX (X=I, Br, Cl)

“…Such numbers would potentially enable the operation of future room temperature spintronics devices. These novel systems, however, are usually the surfaces of bulk metals [6,7], or interfaces grown on metallic substrates [3,8], thus not suitable for technological applications, and also in the rare instances of semiconducting materials, they are artificially grown structures [4,9,10]. For these reasons the advent of an entirely new class of bulk semiconducting materials, the bismuth tellurohalides BiTeX (X = I, Br, Cl), possessing a wide (>100 meV) band gap and hosting bulk and surface states with a large SO splitting (Ref.…”

Many-body interactions and Rashba splitting of the surface state on Cu(110)

“…The Rashba effect has been extensively studied in surface states that are mostly centered at the point of the surface Brillouin zone (SBZ) in many heavy elements, such as Au(111) [2,13,14], Ag/Au(111) [15], and low-index surfaces of Bi [16,17], as well as in the surface alloys Sb/Ag(111) [18], Bi/Ag(111) [19,20], and Bi/Cu(111) [21]. Because SOC is weaker in elements with a smaller nuclear charge, it has been difficult to detect the Rashba splitting in light elements.…”

Unfolding spinor wave functions and expectation values of general operators: Introducing the unfolding-density operator

“…Another important overlooked issue is the problem not only of unfolding the eigenvalues of the crystal Hamiltonian, but the more general one of unfolding the expectation values of any given operator, such as, for instance, the Pauli spin matrices. This is important for the study of, e.g., the spin polarization of graphene's π bands induced by a heavy metal substrate [14][15][16][17][18], as well as in Rashba-type splitting of Shockley surface states on reconstructed surfaces [19,20] and in surface alloys [21][22][23][24].…”