scholarly journals Incommensurate smectic phase in close proximity to the high-Tc superconductor FeSe/SrTiO3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yonghao Yuan ◽  
Xuemin Fan ◽  
Xintong Wang ◽  
Ke He ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Smectic Phase ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
High Tc ◽  
High Tc Superconductor ◽  
Close Proximity ◽  
High Transition ◽  
Transition Surface ◽  
Temperature Scanning

AbstractSuperconductivity is significantly enhanced in monolayer FeSe grown on SrTiO3, but not for multilayer films, in which large strength of nematicity develops. However, the link between the high-transition temperature superconductivity in monolayer and the correlation related nematicity in multilayer FeSe films is not well understood. Here, we use low-temperature scanning tunneling microscopy to study few-layer FeSe thin films grown by molecular beam epitaxy. We observe an incommensurate long-range smectic phase, which solely appears in bilayer FeSe films. The smectic order still locally exists and gradually fades away with increasing film thickness, while it suddenly vanishes in monolayer FeSe, indicative of an abrupt smectic phase transition. Surface alkali-metal doping can suppress the smectic phase and induce high-Tc superconductivity in bilayer FeSe. Our observations provide evidence that the monolayer FeSe is in close proximity to the smectic phase, and its superconductivity is likely enhanced by this electronic instability as well.

scholarly journals Coulomb blockade effects in a topological insulator grown on a high-Tc cuprate superconductor

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Bryan Rachmilowitz ◽  
He Zhao ◽  
Zheng Ren ◽  
Hong Li ◽  
Konrad H. Thomas ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Coulomb Blockade ◽  
Spectral Feature ◽  
Capacitive Coupling ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
High Tc ◽  
Buried Interfaces ◽  
Temperature Scanning ◽  
Fresh Insight

Abstract The evidence for proximity-induced superconductivity in heterostructures of topological insulators and high-Tc cuprates has been intensely debated. We use molecular-beam epitaxy to grow thin films of topological insulator Bi2Te3 on a cuprate Bi2Sr2CaCu2O8+x, and study the surface of Bi2Te3 using low-temperature scanning tunneling microscopy and spectroscopy. In few unit-cell thick Bi2Te3 films, we find a V-shaped gap-like feature at the Fermi energy in dI/dV spectra. By reducing the coverage of Bi2Te3 films to create nanoscale islands, we discover that this spectral feature dramatically evolves into a much larger hard gap, which can be understood as a Coulomb blockade gap. This conclusion is supported by the evolution of dI/dV spectra with the lateral size of Bi2Te3 islands, as well as by topographic measurements that show an additional barrier separating Bi2Te3 and Bi2Sr2CaCu2O8+x. We conclude that the prominent gap-like feature in dI/dV spectra in Bi2Te3 films is not a proximity-induced superconducting gap. Instead, it can be explained by Coulomb blockade effects, which take into account additional resistive and capacitive coupling at the interface. Our experiments provide a fresh insight into the tunneling measurements of complex heterostructures with buried interfaces.

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

Sign in / Sign up

Export Citation Format

Share Document