Charge-density waves studied with the use of a scanning tunneling microscope

Slough, C. G.; McNairy, W. W.; Coleman, R. V.; Drake, B.; Hansma, P. K.

doi:10.1103/physrevb.34.994

Cited by 93 publications

(27 citation statements)

References 35 publications

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“…The initial MoSe 2 sample was prepared by the solid-phase synthesis [13] from selenium and molybdenum and characterized by XRD and elemental analysis. According to XRD, the size of MoSe 2 crystallites was 1000 Å in the basal plane.…”

Section: Preparation Of the Catalystsmentioning

confidence: 99%

Activity of MoSe2/Al2O3 catalysts in decomposition of thiophene and selenophene

Kochubey

Rogov

Babenko

2007

React Kinet Catal Lett

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The rate of thiophene decomposition was shown to be independent of the type of chalcogens used in catalysts МоХ 2 /Al 2 O 3 , where Х = S, Se. On the contrary, the rate of selenophene decomposition was shown to be higher on catalysts MoSe 2 than that on MoS 2 . This observation suggests that the decomposition proceeds on anion vacancies. The decomposition of either thiophene over MoSe 2 or selenophene over MoS 2 results in the formation of partially substituted chalcogenides. At that, the molar ratios of the substituted chalcogen to Mo were shown to coincide in both cases. The fact that the rate of the thiophene decomposition does not depend on the degree of anion exchange indicates that the decomposition is not associated with hydrogenolysis.

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Section: Preparation Of the Catalystsmentioning

confidence: 99%

Activity of MoSe2/Al2O3 catalysts in decomposition of thiophene and selenophene

Kochubey

Rogov

Babenko

2007

React Kinet Catal Lett

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“…8,16 Charge order in 2H -TaSe 2 is incommensurate between 122 and 90 K, below which it locks into a 3a 0 × 3a 0 (with a 0 being the in-plane lattice parameter) commensurate charge modulation. 16,17 The incommensurate CDW has been shown to lead to incomplete gapping. Its form and temperature dependence have been discussed in relationship to the opening of the pseudogap in cuprates.…”

Section: Introductionmentioning

confidence: 99%

“…16 1T -TaSe 2 also develops a charge-density wave at low temperatures, 8,18 with, however, a periodicity of √ 13a 0 × √ 13a 0 rotated by 13.5 • with respect to the atomic lattice. 17,19 Within the CDW state, 1T -TaSe 2 has a high in-plane resistivity and a c-axis mean free path below the interplanar distance. No superconductivity has been reported in this material so far at ambient pressure and without doping.…”

Section: Introductionmentioning

confidence: 99%

Scanning tunneling measurements of layers of superconducting 2H-TaSe2: Evidence for a zero-bias anomaly in single layers

et al. 2013

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We report a characterization of surfaces of the dichalcogenide TaSe 2 using scanning tunneling microscopy and spectroscopy at 150 mK. When the top layer has the 2H structure and the layer immediately below the 1T structure, we find a singular spatial dependence of the tunneling conductance below 1 K, changing from a zero-bias peak on top of Se atoms to a gap in between Se atoms. The zero-bias peak is additionally modulated by the commensurate 3a 0 × 3a 0 charge-density wave of 2H -TaSe 2 . Multilayers of 2H -TaSe 2 show a spatially homogeneous superconducting gap with a critical temperature also of 1 K. We discuss possible origins for the peculiar tunneling conductance in single layers.

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“…Among such materials used in STM are MoS 2 (Weimer et al, 1988), NbSe 2 , 3 (Banda et al, 1988), WS 2 , TaSe 2 , and TaS 2 . Most studies have focused on the observation of charge density waves (CDW) (Coleman et al, 1985;Slough et al, 1986;Thomson et al, 1988), although in recent studies these materials are used as substrates for deposition of metals (Uozumi, 1988) and polymers ).…”

Section: Graphite As a Substratementioning

confidence: 99%

Scanning Tunneling Microscopy

Salmerón

2002

Characterization of Materials

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Scanning tunneling microscopy (STM) is a technique for the determination of the structure of surfaces, with spatial resolution on the angstrom scale. In an oversimplified description, STM allows imaging of the surface of conductive materials down to the atomic level. The technique is based on the measurement and control of the current of electrons tunneling between a sharp stylus (hereafter called the tip) and the sample surface. During imaging, the tip is separated a few angstroms (3 to 10 Å) from the surface, while it is being rastered with the help of piezoelectric transducers. The area scanned is tens to thousands of angstroms on a side. STM has the advantage over other microscopies that its operation does not require any special environmental conditions. Imaging can be performed in vacuum, at high pressures (including air), and in liquids. The choice of the environment is determined mostly by the requirements of the sample and its surface condition. Acquisition of STM images is relatively simple with modern instruments. Most of the experimental time is spent on sample preparation and tip conditioning in the appropriate environment (ultrahigh vacuum, electrochemical cell, or controlled atmosphere). Tip conditioning and noise reduction can sometimes add considerable time, depending on factors such as the nature of the experiment and reactivity of the sample. This time depends also on the type of information being sought. In considering the ultimate resolution obtainable with the STM, it is important to consider the role of tip geometry. On flat parts of the sample, where one tip atom is responsible for the tunneling, STM reaches its maximum performance. On rough surfaces, however, the tunneling point on the tip apex changes as it moves over sharp corners and changing slopes. The image is then a convolution of the tip and surface shapes, and the final resolution is determined by the tip radius and profile. STM is thus not the best technique to probe, for example, highly corrugated a patterned surfaces, and porous materials.

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Charge-density waves studied with the use of a scanning tunneling microscope

Cited by 93 publications

References 35 publications

Activity of MoSe2/Al2O3 catalysts in decomposition of thiophene and selenophene

Activity of MoSe2/Al2O3 catalysts in decomposition of thiophene and selenophene

Scanning tunneling measurements of layers of superconducting 2H-TaSe2: Evidence for a zero-bias anomaly in single layers

Scanning Tunneling Microscopy

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