Synthesis of SnTe Nanoplates with {100} and {111} Surfaces

Abstract

SnTe is a topological crystalline insulator that possesses spin-polarized, Dirac-dispersive surface states protected by crystal symmetry. Multiple surface states exist on the {100}, {110}, and {111} surfaces of SnTe, with the band structure of surface states depending on the mirror symmetry of a particular surface. Thus, to access surface states selectively, it is critical to control the morphology of SnTe such that only desired crystallographic surfaces are present. Here, we grow SnTe nanostructures using vapor-liquid-solid and vapor-solid growth mechanisms. Previously, SnTe nanowires and nanocrystals have been grown [Saghir et al. Cryst. Growth Des. 2014, 14, 2009-2013; Safdar et al. Cryst. Growth Des. 2014, 14, 2502-2509; Safdar et al. Nano Lett. 2013, 13, 5344-5349; Li et al. Nano Lett. 2013, 13, 5443-5448]. In this report, we demonstrate the synthesis of SnTe nanoplates with lateral dimensions spanning tens of micrometers and thicknesses of a few hundred nanometers. The top and bottom surfaces are either (100) or (111), maximizing topological surface states on these surfaces. Magnetotransport on these SnTe nanoplates shows a high bulk carrier density, consistent with bulk SnTe crystals arising due to defects such as Sn vacancies. In addition, we observe a structural phase transition in these nanoplates from the high-temperature rock salt to a low-temperature rhombohedral structure. For nanoplates with a very high carrier density, we observe a slight upturn in resistance at low temperatures, indicating electron-electron interactions.

Unexpected Au Alloying in Tailoring In-Doped SnTe Nanostructures with Gold Nanoparticles

“…Soon after the discovery of SnTe a bulk TCI, several methods to grow SnTe nanostructures by vapor transport with Ar gas flow with/without a gold catalyst were reported [31][32][33][34][35][36]. These suggested that In-SnTe nanostructures can be made available with similar growth methods.…”

Superconducting Sn1–xInxTe Nanoplates

“…[26][27][28][29][30] In particular, SnTe nanoplates with both {100} and {111} surfaces were successfully grown using Au catalyst, but without the catalyst, only nanoblocks of SnTe were reported to grow. 30 Here, we report the growth of Sn1-xInxTe nanoplates with {100} and {111} Figure 1a.…”

“…[26][27][28][29][30] In particular, SnTe nanoplates with both {100} and {111} surfaces were successfully grown using Au catalyst, but without the catalyst, only nanoblocks of SnTe were reported to grow. 30 Here, we report the growth of Sn1-xInxTe nanoplates with {100} and {111} Figure 1a. The growth was performed by first raising the temperature of the source material to 500 °C at the rate of 8 °C/min and then to 600 °C at the rate of 1.7 °C/min; after that, the source temperature was kept at 600 °C [T1 as indicated in Figure 1a] for a specified time period.…”

Surface magnetism in topological crystalline insulators

“…Rotational symmetries in particular yield multiple mirror planes, and connect distinct surface Dirac cones to one another, yielding a multiplicity of easy axis directions. For sufficiently high symmetry, all the surface Dirac points may be related by symmetry operations, resulting in a fully gapped surface spectrum and a large number of groundstate orientations.To illustrate this physics, we present detailed calculations for the (111) surface of (Sn,Pb)Te [8,[20][21][22], using a known model Hamiltonian [3,23]. The (111) surface states are characterized in this system by four surface Dirac points, one at theΓ point and one at each of three Fig.…”