Stabilization and Manipulation of Electronically Phase-Separated Ground States in Defective Indium Atom Wires on Silicon

Abstract

Exploration and manipulation of electronic states in low-dimensional systems are of great importance in the fundamental and practical aspects of nanomaterial and nanotechnology. Here, we demonstrate that the incorporation of vacancy defects into monatomic indium wires on n-type Si(111) can stabilize electronically phase-separated ground states where the insulating 8×2 and metallic 4×1 phases coexist. Furthermore, the areal ratio of the two phases in the phase-separated states can be tuned reversibly by electric field or charge doping, and such tunabilities can be quantitatively captured by first principles-based modeling and simulations. The present results extend the realm of electronic phase separation from strongly correlated d-electron materials typically in bulk form to weakly interacting sp-electron systems in reduced dimensionality.

Equivalence of electronic and mechanical stresses in structural phase stabilization: A case study of indium wires on Si(111)

“…According to our recent STM and DFT study 12 , the vacancy creation in In wires produces a compressive lattice strain to change the relative stability of the 4×1 and 8×2 structures, as discussed below. We here examine how the MS evolves with contracting the lattice constant a of the Si(111) substrate by 1%.…”

“…6(c)]. The latter electronically phase-separated ground state can be attributed to large compressive strains 12 due to high defect density, consistent with the present theoretical prediction that the magnitudes of ∆σ M xx +∆σ M yy and ∆E 8×2−4×1 decrease with contracting a. On the other hand, the ES-driven tuning effect is demonstrated by adopting either n-or p-type substrate: i.e., for a certain defect density, only the 8×2 phase is present on p-type substrate (hole doping) [ Fig.…”

“…For the surface structures formed by epitaxial metal atom adsorption on semiconductor surfaces, there are frequently competing electronic phases 10-13 because of their reduced phase space, and the stability of these phases can be effectively tuned by deforming the lattice 12 or by varying charge carriers 13 . In this sense, the low-dimensional electronic systems formed on surfaces provide a unique playground to demonstrate the tuning effect of phase stability in terms of surface MS and ES (hereafter MS and ES refer to the surface ones).…”

Homogeneous and heterogeneous nucleations in the surface phase transition: Si(111)4 × 1-In

“…A Si(111)-In surface composed of an array of indium atomic chains is a prototypical example undergoing a symmetry-breaking (4 × 1-to-8 × 2) structural phase transition, accompanied by a metalinsulator transition at approximately 120-130 K [3]. Interesting phenomena, such as phase separation [10][11][12][13] and topological soliton excitations [11,[14][15][16], have also been reported in this system.…”

Cooperative interplay between impurities and charge density wave in the phase transition of atomic wires

“…Impurities in this quasi-1D In/Si(111) system affect the phase transition [24][25][26][27][28][29][30], and produce intriguing phenomena such as phase separation [31] and topological soliton excitations [32] as well. While most impurities decreased the T c [25][26][27][28][29], oxygen was exceptional in that it increased the T c [26].…”