Systematics of Molecular Self-Assembled Networks at Topological Insulators Surfaces

Abstract

The success of topological insulators (TI) in creating devices with unique functionalities is directly connected to the ability of coupling their helical spin states to well-defined perturbations. However, up to now, TI-based heterostructures always resulted in very disordered interfaces, characterized by strong mesoscopic fluctuations of the chemical potential that make the spin-momentum locking ill-defined over length scales of few nanometers or even completely destroy topological states. These limitations call for the ability to control topological interfaces with atomic precision. Here, we demonstrate that molecular self-assembly processes driven by inherent interactions among the constituents offer the opportunity to create well-defined networks at TIs surfaces. Even more remarkably, we show that the symmetry of the overlayer can be finely controlled by appropriate chemical modifications. By analyzing the influence of the molecules on the TI electronic properties, we rationalize our results in terms of the charge redistribution taking place at the interface. Overall, our approach offers a precise and fast way to produce tailor-made nanoscale surface landscapes. In particular, our findings make organic materials ideal TIs counterparts, because they offer the possibility to chemically tune both electronic and magnetic properties within the same family of molecules, thereby bringing us a significant step closer toward an application of this fascinating class of materials.

In-plane topological p-n junction in the three-dimensional topological insulator Bi2−xSbxTe3−ySey

“…3 and Supplementary Note 4). Note that F4-TCNQ molecules make an action as additional scattering centers as well as an electron acceptor on the surface of 3D-TIs, whereas the previous report of transition metal phtalocyanine molecules act as an electron donor with absence of backward scattering3435. As shown in Supplementary Fig.…”

Crystal growth of Bi2Te3 and noble cleaved (0001) surface properties

“…Thus, it can be concluded that the chemically cleaned Bi 2 Te 3 (0001) surface can be prepared by the crystal cleavage in the air environment. The specially exposed facets of crystals have been demonstrated to show enhanced properties in various applications [74][75][76][77][78][79][80][81][82]. The Bi 2 Se 3 -type crystals, including Bi 2 Te 3 , possess strongly specific properties of the (0001) surface and this factor should be accounted in the microcrystal growth and TI structure preparation.…”

Activating the molecular spinterface

“…Opening the portfolio of inorganic materials for molecular functionalization could create new opportunities currently only hinted at in the literature 76 . Recently, for example, it has been shown that the hybridization of molecules with skyrmions 77 and topological insulators [78][79][80][81] can be used to modify their topologically protected spin texture. In the specific case of topological insulators (Fig.…”