Z₃ Charge Density Wave of Silicon Atomic Chains on a Vicinal Silicon Surface

Abstract

An ideal one-dimensional electronic system is formed along atomic chains on Au-decorated vicinal silicon surfaces, but the nature of its low-temperature phases has been puzzling for last two decades. Here, we unambiguously identify the low-temperature structural distortion of this surface using high-resolution atomic force microscopy and scanning tunneling microscopy. The most important structural ingredient of this surface, the step-edge Si chains, are found to be strongly buckled, every third atom down, forming trimer unit cells. This observation is consistent with the recent model of rehybridized dangling bonds and rules out the antiferromagnetic spin ordering proposed earlier. The spectroscopy and electronic structure calculation indicate a charge density wave insulator with a Z 3 topology, making it possible to exploit topological phases and excitations. The tunneling current was found to substantially lower the energy barrier between three degenerate CDW states, which induces a dynamically fluctuating CDW at very low temperature.

Transition metal dichalcogenide magnetic atomic chains

“…According to crystal eld theory, the metal ions in MX 2 chains are tetrahedrally coordinated, and the ve d orbitals will split into degenerate e g (d x congurations being 3d 0 , 3d 1 , 3d 2 , and 3d 3 , respectively. The e g orbitals are occupied with one, two, and three electrons, generating one, two, and one unpaired 3d electrons.…”

“…1 One example is atomically thin 2D graphene, which exhibits intriguing physical properties. 2 In spired by the discoveries of 2D atomically thin materials, exploring atomically thin onedimensional (1D) wires (or atomic chains), such as silicon, 3 carbon, 4 pnictogen, 5 chalcogen, 6,7 iodine, 8 metal chain, 9,10 semiconducting compound, 11,12 metal oxide, 13 oxyhydroxide, 14 and molecular wire [15][16][17] etc., provoking enormous attentions for exotic electronic properties, ranging from strong quantum confinement, 18,19 novel edge states, 20,21 to polarization, 22,23 as well as wide applications in nanoconnectors, 10,24 transistors, 25 optoelectronics, 26 catalysts, 27,28 and spintronics 15,29 .…”

Diffusion-Dependent Pattern Formation on Crystal Surfaces

“…From our point of view, the most interesting is the analysis of the vicinal surface, which is the subject of several theoretical and experimental studies. − This type of surface is important in catalysis during the growth of nanostructures or engineering since steps are active sites for nucleation or chemical reactions. Many previous investigations have focused on the growth of crystals in different aspects, − step bunching or meandering. − In particular, the emergence of the step-bunching instability has been systematically studied .…”

Quasi-Periodic Growth of One-Dimensional Copper Boride on Cu(110)

“…An appropriate choice of a 1-D template, such as the Cu (110) surface of the fcc crystal, has enabled us to grow atomic chains. 10,11 Thus, a formation of the copper boride interface on Cu(110) is expected to lead to a unique 1-D system that can be characterized with surface-sensitive imaging, such as scanning tunneling microscopy (STM).…”

“…This unique environment has opened new research fields and has provided a space to examine interface materials that cannot be explored in a pure 2-D system. − One of the recent findings was a long-range ordered layer of copper boride (Cu-Boride) that was grown incommensurately on the (111) surface of a copper crystal. − This was unexpected because boron has been known to rarely form bulk compounds with group 11 elements. , Moreover, the 2-D copper boride was composed of an alternating array of boron and copper chains, which indicated an intriguing relationship between the 2-D and 1-D atomic structures. An appropriate choice of a 1-D template, such as the Cu (110) surface of the fcc crystal, has enabled us to grow atomic chains. , Thus, a formation of the copper boride interface on Cu(110) is expected to lead to a unique 1-D system that can be characterized with surface-sensitive imaging, such as scanning tunneling microscopy (STM).…”