Correlation between crystal purity and the charge density wave in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mi>T</mml:mi><mml:mo>−</mml:mo><mml:msub><mml:mi>VSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Sayers, Charles J.; Farrar, Liam; Bending, S. J.; Cattelan, Mattia; Jones, Alfred J. H.; Fox, Neil A.; Kociok‐Köhn, Gabriele; Koshmak, Konstantin; Laverock, J.; Pasquali, Luca; Como, Enrico Da

doi:10.1103/physrevmaterials.4.025002

Cited by 20 publications

(25 citation statements)

References 42 publications

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“…Given these promising results, we believe it is worthwhile to develop and refine combined ultrafast techniques. Our approach can be employed to investigate the detailed mechanisms driving the phase transitions in a wide range of strongly correlated materials [70][71][72].…”

Section: Discussionmentioning

confidence: 99%

Investigation of the non-equilibrium state of strongly correlated materials by complementary ultrafast spectroscopy techniques

et al. 2021

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Photoinduced non-thermal phase transitions are new paradigms of exotic non-equilibrium physics of strongly correlated materials. An ultrashort optical pulse can drive the system to a new order through complex microscopic interactions that do not occur in the equilibrium state. Ultrafast spectroscopies are unique tools to reveal the underlying mechanisms of such transitions which lead to transient phases of matter. Yet, their individual specificities often do not provide an exhaustive picture of the physical problem. One effective solution to enhance their performance is the integration of different ultrafast techniques. This provides an opportunity to simultaneously probe physical phenomena from different perspectives while maintaining the same experimental conditions. In this context, we performed complementary experiments by combining time-resolved reflectivity and time and angle-resolved photoemission spectroscopy. We demonstrate the advantage of this combined approach by investigating the complex charge density wave (CDW) phase in 1T-TiSe 2 . Specifically, we show the key role of lattice degrees of freedom to establish and stabilize the CDW in this material.

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Section: Discussionmentioning

confidence: 99%

Investigation of the non-equilibrium state of strongly correlated materials by complementary ultrafast spectroscopy techniques

et al. 2021

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“…This conclusion is supported by reports from both chemical vapour transport (CVT) crystal growth of TMDs and CVD growth utilising W(CO) 6 as the W source [8,20,52]. In the case of CVT growth, studies have shown that the materials suffer from a natural chalcogen deficiency due to the volatility of the chalcogen atoms [53,54]. To alleviate this, CVTproduced TMDs are deliberately grown with a stoichiometric ratio greater than 2:1 (chalcogen: metal).…”

Section: Resultsmentioning

confidence: 94%

Optimisation of processing conditions during CVD growth of 2D WS2 films from a chloride precursor

et al. 2022

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Monolayer tungsten disulphide (WS2) is a direct band gap semiconductor which holds promise for a wide range of optoelectronic applications. The large-area growth of WS2 has previously been successfully achieved using a W(CO)6 precursor, however, this is flammable and a potent source of carbon monoxide (CO) upon decomposition. To address this issue, we have developed a process for the wafer-scale growth of monolayer WS2 from a tungsten hexachloride (WCl6) precursor in a commercial cold-wall CVD reactor. In comparison to W(CO)6, WCl6 is less toxic and less reactive and so lends itself better to the large-scale CVD growth of 2D layers. We demonstrate that a post-growth H2S anneal can lead to a dramatic improvement in the optical quality of our films as confirmed by photoluminescence (PL) and Raman measurements. Optimised films exhibit PL exciton emission peaks with full width at half maximum of 51 ± 2 meV, comparable to other state-of-the-art methods. We demonstrate that our WS2 films can be readily transferred from the sapphire growth substrate to a Si/SiO2 target substrate with no detectable degradation in quality using a polystyrene support layer. Our approach represents a promising step towards the industrial-scale fabrication of p-n junctions, photodetectors and transistors based on monolayer WS2.

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“…The preparation and characterisation of single crystals of VSe 2 are extensively reported in Ref. [16]. In summary, it was reported that in order to obtain near ideal stoichiometry and to minimise the presence of defects, samples were prepared by chemical vapour transport at a growth temperature of 550 • C. Electrical transport measurements show a residual resistance ratio or RRR = 49 and a CDW transition temperature, T c = 112.7 K. The work reported here was carried out on a single crystal with approximate dimensions of 2 × 3 mm.…”

Section: Methodsmentioning

confidence: 99%

“…For example, angle resolved photoemission and scanning tunnelling spectroscopy experiments report gap sizes varying between 13 to 130 meV [7,8,11,14,15]. Recently, some of us reported the sensitivity of the CDW properties to defects and overall stoichiometry [16]. It was demonstrated that depending on sample growth conditions the defects and Se deficiencies proliferate, while optimal growth conditions can be achieved to produce stoichiometric, clean crystals with an enhanced critical transition temperature for the CDW phase.…”

Section: Introductionmentioning

confidence: 99%

Observation of the charge density wave collective mode in the infrared optical response of VSe$_2$

Feng,

Henke,

Morice

et al. 2021

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We present a detailed study of the bulk electronic structure of high quality VSe2 single crystals using optical spectroscopy. Upon entering the charge density wave phase below the critical temperature of 112 K, the optical conductivity of VSe2 undergoes a significant rearrangement. A Drude response present above the critical temperature is suppressed while a new interband transition appears around 0.07 eV. From our analysis, we estimate that part of the spectral weight of the Drude response is transferred to a collective mode of the CDW phase. The remaining normal state charge dynamics appears to become strongly damped by interactions with the lattice as evidenced by a mass enhancement factor m * /m≈3. In addition to the changes taking place in the electronic structure, we observe the emergence of infrared active phonons below the critical temperature associated with the 4a × 4a lattice reconstruction.

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Correlation between crystal purity and the charge density wave in 1T−VSe2

Cited by 20 publications

References 42 publications

Investigation of the non-equilibrium state of strongly correlated materials by complementary ultrafast spectroscopy techniques

Investigation of the non-equilibrium state of strongly correlated materials by complementary ultrafast spectroscopy techniques

Optimisation of processing conditions during CVD growth of 2D WS2 films from a chloride precursor

Observation of the charge density wave collective mode in the infrared optical response of VSe$_2$

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