Electronic conduction process in 1T-TaS2

Hambourger, Paul D.; Salvo, F. J. Di

doi:10.1016/0378-4363(80)90227-2

Cited by 23 publications

(10 citation statements)

References 7 publications

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“…The previously published values of resistivity anisotropy of 1T-TaS 2 in the C and NC phases are in the range of hundreds 10 and thousands 11 , which is suspiciously high given the results of recent band structure calculations and angle resolved photoemission spectroscopy experiments, indicating a sizeable band dispersion along the k z axis of the Brillouin zone [31][32][33][34][35] . A plot of our data for ρ ⊥ and ρ ǁ of 1T-TaS 2 between 2 K and 400 K (Fig.…”

Section: Anomalously Low Resistivity Anisotropymentioning

confidence: 88%

“…Characterisation of the coupling between the layers in van der Waals materials is therefore of great interest, and valuable information can be revealed by probing the out-of-plane charge transport. However, contrary to its in-plane counterpart this property has not been given a lot of attention so far, with the existing data being rather scarce and in some cases inconsistent [7][8][9][10][11] . With the aforementioned discoveries in mind, one can raise a question: to what extent can various layered materials be really classified as quasi-two-dimensional?…”

Section: Introductionmentioning

confidence: 99%

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Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS2

et al. 2020

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Layered transition metal dichalcogenides (TMDs) are commonly classified as quasi-two-dimensional materials, meaning that their electronic structure closely resembles that of an individual layer, which results in resistivity anisotropies reaching thousands. Here, we show that this rule does not hold for 1T-TaS 2-a compound with the richest phase diagram among TMDs. Although the onset of charge density wave order makes the in-plane conduction non-metallic, we reveal that the out-of-plane charge transport is metallic and the resistivity anisotropy is close to one. We support our findings with ab initio calculations predicting a pronounced quasi-onedimensional character of the electronic structure. Consequently, we interpret the highly debated metal-insulator transition in 1T-TaS 2 as a quasi-one-dimensional instability, contrary to the long-standing Mott localisation picture. In a broader context, these findings are relevant for the newly born field of van der Waals heterostructures, where tuning interlayer interactions (e.g., by twist, strain, intercalation, etc.) leads to new emergent phenomena.

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Section: Anomalously Low Resistivity Anisotropymentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS2

et al. 2020

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“…To this end, we assume that the heat dissipation process can be simulated effectively by a 1D model. At first glance, electrical transport measurements point to negligible outof-plane heat conduction as they reveal an out-of-plane to in-plane resistivity anisotropy of ρ ⊥ /ρ = 500 [79]. However, the anisotropy between the spot diameter, d OPT = 1 mm, and the penetration depth into the bulk, z OPT = 33 nm, of the optical pump beam is two orders of magnitude larger.…”

Section: Heat Diffusion Dynamicsmentioning

confidence: 99%

Time-resolved x-ray photoelectron spectroscopy at FLASH

et al. 2012

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Coherent and incoherent excitations of the Gd(0001) surface on ultrafast timescales Uwe Bovensiepen -Time-resolved HAXPES at SACLA: probe and pump pulse-induced space-charge effects L-P Oloff, M Oura, K Rossnagel et al. Abstract. The technique of time-resolved pump-probe x-ray photoelectron spectroscopy using the free-electron laser in Hamburg (FLASH) is described in detail. Particular foci lie on the macrobunch resolving detection scheme, the role of vacuum space-charge effects and the synchronization of pump and probe lasers. In an exemplary case study, the complete Ta 4f core-level dynamics in the layered charge-density-wave (CDW) compound 1T-TaS 2 in response to impulsive optical excitation is measured on the sub-picosecond to nanosecond timescale. The observed multi-component dynamics is related to the intrinsic melting and reformation of the CDW as well as to extrinsic pump-laser-induced vacuum space-charge effects.

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“…In fact, a direct measurement of ρ c /ρ a gives a value of approximately 500 [35], even in the temperature range of metallic conductance. The apparent contradiction of a metallic band with a lack of metallic conduction could be due to a gap opening in the one-dimensional dispersion near E F .…”

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confidence: 99%

Quasi-one-dimensional metallic band dispersion in the commensurate charge density wave of 1T−TaS2

et al. 2017

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The commensurate charge density wave (CDW) in the layered compound 1T -TaS2 has hitherto mostly been treated as a quasi two-dimensional phenomenon. Recent band structure calculations have, however, predicted that the CDW coexists with a nearly one-dimensional metallic dispersion perpendicular to the crystal planes. Using synchrotron radiation based angle-resolved photoemission spectroscopy, we show that this metallic band does in fact exist. Its occupied band width is in excellent agreement with predictions for a simple τc stacking order of the CDW between adjacent layers and its periodicity in the c direction is 2π/c.The 1T polytype of TaS 2 is one of the most studied layered transition metal dichalcogenides (TMDCs). Its rich electronic phase diagram involves several charge density wave (CDW) transitions driven by strong electronic correlations and electron-phonon coupling [1,2]. Particular focus has been on the ground state below 180 K which is a commensurate CDW phase with a √ 13 × √ 13 socalled Star of David reconstruction that is rotated by 13.9• against the lattice. In this phase, the large-scale periodic lattice distortion is thought to coexist with a Mott insulating ground state arising from the single electron localized on the centre atom of the Star of David [1,3]. While the research on CDWs in layered TMDCs is more than 40 years old, renewed interest has been driven by the possibility to elucidate transitions between different CDW states using ultrafast techniques [4][5][6][7][8][9]; by the observation of metastable "hidden states" [9]; and by the experimental accessibility of metallic TMDCs as single layers [10,11].The realization that CDWs could be different in single layer TMDCs than in analogous bulk materials has drawn attention to the fact that viewing the bulk materials' electronic properties as essentially two-dimensional might be an oversimplification. While reduced dimensionality has a significant impact on electronic instabilities, due to increased electronic correlations and electron-phonon coupling, interlayer coupling also appears to be essential for a full understanding of the electronic properties of these materials [12][13][14][15][16][17]. Specifically, several calculations predict a one-dimensional metallic band formation along the Γ − A direction of the Brillouin zone in the ground state CDW of 1T -TaS 2 (i.e., perpendicular to the planes). This is found in density functional theory calculations [12,16,17], even when electronic correlations are taken into account [14,15]. While the metallic band along Γ−A is universally found in all calculations, the details of the dispersion depend on the stacking order of the CDW unit cell between adjacent planes [15,16]. Angle-resolved photoemission spectroscopy (ARPES)is an experimental technique capable of determining the three-dimensional band structure of crystalline solids, and numerous ARPES studies have been performed on 1T -TaS 2 (for a review see Ref.[2]). However, very little attention has been paid to the possibly three-dimensional ch...

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Electronic conduction process in 1T-TaS2

Cited by 23 publications

References 7 publications

Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS2

Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS2

Time-resolved x-ray photoelectron spectroscopy at FLASH

Quasi-one-dimensional metallic band dispersion in the commensurate charge density wave of 1T−TaS2

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