Direct observation of competition between charge order and itinerant ferromagnetism in vdW crystal Fe5-xGeTe2

Abstract The interplay of symmetry-breaking ordered states, such as superconductivity, charge density waves (CDW), magnetism and pseudogap, is a fundamental issue in correlated system. CDW and antiferromagnetism often coexist in the proximity of phase diagram region in cuprates. It is also worthy nothing that different order states appear in a situation on comparable temperature scales, so these orders are intertwined and competing on the same footing. The magnetism of vdW material Fe5-xGeTe2 with the one of the highest reported bulk Curie temperatures, is found to be sensitive to thermal history and external magnetic field. However, the temperature-dependent magnetization with two characteristic points still lacks a unified picture to describe. Using angle-resolved photoemission spectroscopy, scanning tunneling microscopy, magnetic properties measurements, and the first-principles calculations, the complex yet intriguing magnetic behaviors are gradually unveiled. A competition mechanism between charge order and ferromagnetism is proposed and firmly observed by experimental measurements. As the ferromagnetic order strengthens at low temperature, the charge order will be suppressed. Exchange splitting in itinerant ferromagnetism plays a significant role in the temperature evolution of band structure and causes a Lifshitz transition, which provides more control means to realize novel devices at room temperature.

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STM studies of crystal growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086179 ◽

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.

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Atomic origin of the scanning tunneling microscopy images of charge-density-waves on 1T-TaSe2

Physica B Condensed Matter ◽

10.1016/j.physb.2007.11.026 ◽

2008 ◽

Vol 403 (13-16) ◽

pp. 2207-2210 ◽

Cited By ~ 1

Author(s):

D. Stoltz ◽

M. Bielmann ◽

L. Schlapbach ◽

M. Bovet ◽

H. Berger ◽

...

Keyword(s):

Scanning Tunneling Microscopy ◽

Charge Density ◽

Charge Density Waves ◽

Scanning Tunneling ◽

Density Waves ◽

Tunneling Microscopy ◽

Microscopy Images

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Images of charge-density waves obtained with scanning tunneling microscopy

Surface Science Letters ◽

10.1016/0167-2584(87)90714-6 ◽

1987 ◽

Vol 181 (1-2) ◽

pp. A86

Author(s):

R.V. Coleman ◽

W.W. McNairy ◽

C.G. Slough ◽

P.K. Hansma ◽

B. Drake

Keyword(s):

Scanning Tunneling Microscopy ◽

Charge Density ◽

Charge Density Waves ◽

Scanning Tunneling ◽

Density Waves ◽

Tunneling Microscopy

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Density of states modulations from oxygen phonons ind-wave superconductors: Reconciling angle-resolved photoemission spectroscopy and scanning tunneling microscopy

Physical Review B ◽

10.1103/physrevb.81.214512 ◽

2010 ◽

Vol 81 (21) ◽

Cited By ~ 14

Author(s):

S. Johnston ◽

T. P. Devereaux

Keyword(s):

Scanning Tunneling Microscopy ◽

Density Of States ◽

Photoemission Spectroscopy ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Angle Resolved Photoemission Spectroscopy

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STM STUDIES OF ELECTRONIC ORDER IN THE UNDERDOPED SURFACE OF YBa2Cu3Oy

International Journal of Modern Physics B ◽

10.1142/s0217979207044184 ◽

2007 ◽

Vol 21 (18n19) ◽

pp. 3199-3201

Author(s):

TERUKAZU NISHIZAKI ◽

NORIO KOBAYASHI ◽

MAKOTO MAKI

Keyword(s):

Low Temperature ◽

Scanning Tunneling ◽

Long Range Order ◽

Tunneling Microscopy ◽

One Dimensional ◽

Stm Image ◽

Temperature Scanning ◽

The One ◽

Carrier Doping ◽

Electronic Order

To study the nanoscale electronic order in high-T c superconductors, we have performed low-temperature scanning tunneling microscopy (STM) experiments on YBa 2 Cu 3 O y, single crystals. The electronic state of the underdoped CuO 2 plane is studied through the BaO surface taking advantage of the cleaved surface, which has an insufficient carrier doping into the topmost CuO 2 plane because of the incomplete carrier reservoir. The STM image measured at low bias-voltage below 20 mV shows the one-dimensional (1D) electronic modulation along the Cu - O bonds. The 1D modulation do not have long-range order and the periodicity varies within the range ~ 2a - 4a depending on the position on the surface. These results indicate that electronic order in underdoped YBa 2 Cu 3 O y, differs from the 4a×4a checkerboard structure observed in Bi 2 Sr 2 CaCu 2 O y and Ca 2-x Na x CuO 2 Cl 2.

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Charge-density waves observed at 4.2 K by scanning-tunneling microscopy

Physical Review B ◽

10.1103/physrevb.37.2741 ◽

1988 ◽

Vol 37 (5) ◽

pp. 2741-2744 ◽

Cited By ~ 58

Author(s):

B. Giambattista ◽

A. Johnson ◽

R. V. Coleman ◽

B. Drake ◽

P. K. Hansma

Keyword(s):

Scanning Tunneling Microscopy ◽

Charge Density ◽

Charge Density Waves ◽

Scanning Tunneling ◽

Density Waves ◽

Tunneling Microscopy

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Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization

10.26434/chemrxiv.12771254 ◽

2020 ◽

Author(s):

Anja Haags ◽

Alexander Reichmann ◽

Qitang Fan ◽

Larissa Egger ◽

Hans Kirschner ◽

...

Keyword(s):

Electronic Structure ◽

Density Functional ◽

Photoemission Spectroscopy ◽

Scanning Tunneling ◽

Orbital Structure ◽

Tunneling Microscopy ◽

Angle Resolved Photoemission Spectroscopy ◽

Highest Occupied Molecular Orbital ◽

Shed Light ◽

Aromatic Stabilization

We revisit the question of kekulene’s aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene’s highest occupied molecular orbital by photoelectron tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C–C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.<br>

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Twisted charge-density-wave patterns in bilayer 2D crystals and modulated electronic states

2D Materials ◽

10.1088/2053-1583/ac427f ◽

2021 ◽

Author(s):

Yaoyao Chen ◽

Liwei Liu ◽

Xuan Song ◽

Han Yang ◽

zeping Huang ◽

...

Keyword(s):

Charge Density ◽

Density Wave ◽

Single Layer ◽

Interlayer Coupling ◽

Charge Density Waves ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Atomic Lattices ◽

Fresh Insight ◽

2D Crystals

Abstract The twistronics of the atomic-thick two-dimensional (2D) van der Waals materials has opened a new venue to investigate the interlayer coupling. Till now, most studies focus on the twist of atomic lattices and the resulted moiré superstructures, while the reports about the twist of charge density waves (CDW), the superstructures of which are from individual layers are limited. Here, using molecular beam epitaxy, we construct bilayer (BL) 1T-NbSe2 vertical structures. With high resolution scanning tunneling microscopy observations, we identify two cases of CDW twisted stacking with atomic precision. The typical twist angles are 0o and 60o between the 1st and the 2nd layer, although the top Se atomic lattices of these two layers are parallel. Compared to the single layer case, the dI/dV at BL shows an insulator-to-metal transition, with the Hubbard bands shrinking towards the Fermi level (EF ). More intriguingly, interlayer coupling states rise near EF , which are dependent on the CDW twist angles. These findings give fresh insight into the engineering of 2D materials by CDW twisting and are potentially applicable for future nanoelectronic devices.

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GROWTH AND STABILITY OF ULTRA-THIN Pb FILMS ON Pb/Si(111)-α-√3 × √3

Surface Review and Letters ◽

10.1142/s0218625x11014473 ◽

2011 ◽

Vol 18 (01n02) ◽

pp. 77-82

Author(s):

WEN-JUAN LI ◽

YU-JIE SUN ◽

XIE-GANG ZHU ◽

GUANG WANG ◽

YAN-FENG ZHANG ◽

...

Keyword(s):

Low Temperature ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Temperature Dependent ◽

Angle Resolved Photoemission Spectroscopy ◽

Thermal Expansion Coefficients ◽

Interface Charge ◽

Temperature Scanning ◽

Surface Morphologies ◽

Atomically Flat

Ultra-thin Pb films with magic thicknesses of 2 monolayer (ML), 4 ML and 6 ML were prepared of atomically flat on the substrate of Si (111)-α-√3 × √3 (or SIC phase) at 145 K. Their surface morphologies and stability were studied by low temperature scanning tunneling microscopy and temperature-dependent angle resolved photoemission spectroscopy. We found that the well ordered SIC interface can lower the diffusion barrier and enhance the interface charge transfer, leading to different critical thickness compared to Pb / Si (111)-7 × 7 grown under same conditions. Enhanced thermal expansion coefficients were also observed in ultra-thin Pb films at low temperature.

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