Topological electronic structure and Rashba effect in Bi thin layers: theoretical predictions and experiments

Abstract

The goal of the present review is to cross-compare theoretical predictions with selected experimental results of spin-and angle-resolved photoelectron spectroscopy on bismuth thin films exhibiting topological properties and a strong Rashba effect. Despite the bulk Bi crystal is topologically trivial, a single free-standing Bi(1 1 1) bilayer has been predicted by calculations to be a topological insulator. This triggered a large series of studies of ultrathin Bi(1 1 1) films grown on various substrates. Using selected examples we review theoretical predictions of atomic and electronic structure of Bi thin films exhibiting topological properties due to interaction with a substrate. We survey as well experimental signatures of topological surface states, as obtained namely by angle-resolved photoelectron spectroscopy.

Bi ultra-thin crystalline films on InAs(1 1 1)A and B substrates: a combined core-level and valence-band angle-resolved and dichroic photoemission study

“…Along this line many investigations of the changes with respect to bulkBi of the electronic structure of Bi thin films deposited on semiconductors, e.g.Si(1 1 1) [7,8], SiC(0 0 0 1) [9], and highly-oriented pyrolytic graphite [10], have been performed. Such studies on Bi thin films are also of importance for a better understanding of the physical properties of topological insulators [1,3,[11][12][13]] (see also [14] review).…”

Tailoring the electronic structure of thin Bi films via the growth on vicinal Ge(111)

“…5 In addition, as a consequence of its large atomic number, the spin-orbit interaction plays a relevant role in determining the Bi electronic band structure. For instance, surface electronic states are split in spin-polarized bands by the so-called Rashba effect, 6,7 an occurrence that can be exploited in the field of spintronics for, e.g., the generation and manipulation of spin currents. [8][9][10] For such technological applications, Bi is employed in the form of thin films or nanostructures.…”

“…13,[19][20][21][22] The (111) face of Si and Ge guarantees the growth of high quality Bi films, which proceeds via the formation and successive coalescence of islands with a crystallographic structure reminiscent of the rhombohedral lattice of bulk Bi, which can be viewed as a stack of buckled bilayers (BL), with one bilayer weakly bonded to the adjacent ones along the [111] direction. 6 The exact crystallographic evolution of Bi films is rather complex and influenced by several factors, including the substrate temperature and the actual atomic arrangement at the Bi/semiconductor interface. 11,23 Generally, at low coverages a Bi(110)-like, or "pseudocubic" face is usually observed, while at larger Bi coverages an "hexagonal" Bi(111) face is stabilized.…”

Structural properties of Bi/Au(110)

“…Different ordered structures were observed. At low coverage (<1 ML) Bi arrays and 2D structure were obtained while at higher coverage (>1 ML) the thicker Bi films grow with lattice constant close to the (110) surface of bulk Bi [41].…”