TaS2

/Tag: TaS2

Interlayer coupling and the phase transition mechanism of stacked MoS2/TaS2 heterostructures discovered using temperature dependent Raman and photoluminescence spectroscopy

2018-06-14T14:32:24+00:00 June 14th, 2018|Categories: Publications|Tags: , , , |

RSC Adv., 2018, 8,21968-21974DOI: 10.1039/C8RA03436B, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Miao Chen, Bin Zhou, Fang Wang, Liping Xu, Kai Jiang, Liyan Shang, Zhigao Hu, Junhao ChuThe important interlayer coupling of the MoS2-TaS2 heterostructure

Published in: "RSC Advances".

Tuning Ising superconductivity with layer and spin–orbit coupling in two-dimensional transition-metal dichalcogenides

2018-04-12T10:32:03+00:00 April 12th, 2018|Categories: Publications|Tags: , , |

Tuning Ising superconductivity with layer and spin–orbit coupling in two-dimensional transition-metal dichalcogenidesTuning Ising superconductivity with layer and spin–orbit coupling in two-dimensional transition-metal dichalcogenides, Published online: 12 April 2018; doi:10.1038/s41467-018-03888-4Monolayer transition-metal dichalcogenide (TMD) is promising to host features of topological superconductivity. Here, de la Barrera et al. study layered compounds, 2H-TaS2 and 2H-NbSe2, in their atomic layer limit and find a largest upper critical field for an intrinsic TMD superconductor.

Published in: "Nature Communications".

Vertical 1T-TaS2 Synthesis on Nanoporous Gold for High-Performance Electrocatalytic Applications

2018-03-07T08:31:50+00:00 March 7th, 2018|Categories: Publications|Tags: , , |

Abstract 2D metallic TaS2 is acting as an ideal platform for exploring fundamental physical issues (superconductivity, charge-density wave, etc.) and for engineering novel applications in energy-related fields. The batch synthesis of high-quality TaS2 nanosheets with a specific phase is crucial for such issues. Herein, the successful synthesis of novel vertically oriented 1T-TaS2 nanosheets on nanoporous gold substrates is reported, via a facile chemical vapor deposition route. By virtue of the abundant edge sites and excellent electrical transport property, such vertical 1T-TaS2 is employed as high-efficiency electrocatalysts in the hydrogen evolution reaction, featured with rather low Tafel slopes ≈67–82 mV dec−1 and an ultrahigh exchange current density ≈67.61 µA cm−2. The influence of phase states of 1T- and 2H-TaS2 on the catalytic activity is also discussed with the combination of density functional theory calculations. This work hereby provides fundamental insights into the controllable syntheses and electrocatalytic applications of vertical 1T-TaS2 nanosheets achieved through the substrate engineering. Vertically oriented 1T-TaS2 nanosheets are first synthesized on nanoporous gold (NPG) substrates, via the chemical vapor deposition route. By virtue of the abundant edge sites and excellent electrical transport property, such vertical 1T-TaS2/NPG are employed as high-efficiency electrocatalysts in the hydrogen evolution reaction. The influence of the phase states of TaS2 on the catalytic activity is also explored according to theoretical calculations.

Published in: "Advanced Materials".

Low-Frequency Noise and Sliding of the Charge Density Waves in Two-Dimensional Materials. (arXiv:1802.02536v1 [cond-mat.mes-hall])

2018-02-08T19:58:45+00:00 February 8th, 2018|Categories: Publications|Tags: , |

There has been a recent renewal of interest in charge-density-wave (CDW) phenomena, primarily driven by the emergence of two-dimensional (2D) layered CDW materials, such as 1T-TaS2, characterized by very high transition temperatures to CDW phases. In the extensively studied classical bulk CDW materials with quasi-1D crystal structure, the charge carrier transport exhibits intriguing sliding behavior, which reveals itself in the frequency domain as “narrowband” and “broadband” noise. Despite the increasing attention on physics of 2D CDWs, there have been few reports of CDW sliding, specifically in quasi-2D rare-earth tritellurides and none on the noise in any of 2D CDW systems. Here we report the results of low-frequency noise (LFN) measurements on 1T-TaS2 thin films – archetypal 2D CDW systems, as they are driven from the nearly commensurate (NC) to incommensurate (IC) CDW phases by voltage and temperature stimuli. We have found that noise in 1T-TaS2 devices has two pronounced maxima at the bias voltages, which correspond to the onset of CDW sliding and the NC-to-IC phase transition. We observed unusual Lorentzian noise features and exceptionally strong noise dependence on electric bias and temperature. We argue that LFN in 2D CDW systems has unique physical origin, different from known fundamental noise types. The specifics of LFN in 2D CDW materials can be explained by invoking the concept of interacting discrete fluctuators in the NC-CDW phase. Noise spectroscopy can serve as a useful tool for understanding electronic transport phenomena in 2D CDW materials characterized by coexistence of different phases and strong CDW

Published : "arXiv Mesoscale and Nanoscale Physics".

Infrared nanoimaging of the metal-insulator transition in the charge-density-wave van der Waals material $1Ttext{−}{mathrm{TaS}}_{2}$

2018-01-08T16:30:57+00:00 January 8th, 2018|Categories: Publications|Tags: , |

Author(s): Alex J. Frenzel, Alexander S. McLeod, Dennis Zi-Ren Wang, Yu Liu, Wenjian Lu, Guangxin Ni, Adam W. Tsen, Yuping Sun, Abhay N. Pasupathy, and D. N. BasovUsing scanning near-field optical microscopy at cryogenic temperatures, we explored the first-order metal-insulator transition of exfoliated 1T−TaS2 microcrystals on a SiO2/Si substrate. We clearly observed spatially separated metallic and insulating states during the transition between commensurate…[Phys. Rev. B 97, 035111] Published Mon Jan 08, 2018

Published in: "Physical Review B".

Two-dimensional tantalum disulfide: controlling structure and properties via synthesis

2018-01-02T14:30:48+00:00 January 2nd, 2018|Categories: Publications|Tags: , |

Tantalum disulfide (TaS 2 ) is a transition metal dichalcogenide (TMD) that exhibits phase transition induced electronic property modulation at low temperature. However, the appropriate phase must be grown to enable the semiconductor/metal transition that is of interest for next generation electronic applications. In this work, we demonstrate direct and controllable synthesis of ultra-thin 1T-TaS 2 and 2H-TaS 2 on a variety of substrates (sapphire, SiO 2 /Si, and graphene) via powder vapor deposition. The synthesis process leads to single crystal domains ranging from 20 to 200 nm thick and 1–10 µ m on a side. The TaS 2 phase (1T or 2H) is controlled by synthesis temperature, which subsequently is shown to control the electronic properties. Furthermore, this work constitutes the first demonstration of a metal–insulator phase transition in directly synthesized 1T-TaS 2 films and domains by electronic means.

Published in: "2DMaterials".

Unusual enhancements of B_{c2} and T_c in the restacked TaS_2 nanosheets. (arXiv:1712.07763v1 [cond-mat.supr-con])

2017-12-22T19:59:26+00:00 December 22nd, 2017|Categories: Publications|Tags: , |

Recently we reported an enhanced superconductivity in restacked monolayer TaS_2 nanosheets compared with the bulk TaS2, pointing to the exotic physical properties of low dimensional systems. Here we tune the superconducting properties of this system with magnetic field along different directions, where a strong Pauli paramagnetic spin-splitting effects is found in this system. Importantly, an unusual enhancement as high as 3.8 times of the upper critical field B_{c2} is observed under the inclined external magnetic field. Moreover, with the vertical field fixed, we find that the superconducting transition temperature T_c can be enhanced by increasing the transverse field and forms a dome-shaped phase diagram. We argue that the restacked crystal structure without inversion center along with the strong spin-orbit coupling may play a key role for our observations. The present findings are significant in the viewpoint of fundamental physics and may also facilitate the applications of low-dimensional superconductors in the environment of high field.

Published in: "arXiv Material Science".

Total Ionizing Dose Effects on Threshold Switching in 1T-Tantalum Disulfide Charge-Density-Wave Devices. (arXiv:1712.01354v1 [physics.app-ph])

2017-12-06T19:58:52+00:00 December 6th, 2017|Categories: Publications|Tags: , |

The 1T polytype of TaS2 exhibits voltage-triggered threshold switching as a result of a phase transition from nearly commensurate to incommensurate charge density wave states. Threshold switching, persistent above room temperature, can be utilized in a variety of electronic devices, e.g., voltage controlled oscillators. We evaluated the total-ionizing-dose response of thin film 1T-TaS2 at doses up to 1 Mrad(SiO2). The threshold voltage changed by less than 2% after irradiation, with persistent self-sustained oscillations observed through the full irradiation sequence. The radiation hardness is attributed to the high intrinsic carrier concentration of 1T-TaS2 in both of the phases that lead to threshold switching. These results suggest that charge density wave devices, implemented with thin films of 1T-TaS2, are promising for applications in high radiation environments.

Published : "arXiv Mesoscale and Nanoscale Physics".

Total-Ionizing-Dose Effects on Threshold Switching in $1{T}$ -TaS2 Charge Density Wave Devices

2017-11-24T01:21:23+00:00 November 24th, 2017|Categories: Publications|Tags: , |

The $1{T}$ polytype of TaS2 exhibits voltage-triggered threshold switching as a result of a phase transition from nearly commensurate to incommensurate charge density wave states. Threshold switching, persistent above room temperature, can be utilized in a variety of electronic devices, e.g., voltage controlled oscillators. We evaluated the total-ionizing-dose response of thin film $1{T}$ -TaS2 at doses up to 1 Mrad (SiO2). The threshold voltage changed by less than 2% after irradiation, with persistent self-sustained oscillations observed through the full irradiation sequence. The radiation hardness is attributed to the high intrinsic carrier concentration of $1{T}$ -TaS2 in both of the phases that lead to threshold switching. These results suggest that charge density wave devices, implemented with thin films of $1{T}$ -TaS2, are promising for applications in high radiation environments.

Published in: "IEEE Electron Device Letters".

Atom-scale dispersed palladium in conductive Pd0.1TaS2 lattice with unique electronic structure for efficient hydrogen evolution

2017-10-04T13:18:30+00:00 October 4th, 2017|Categories: Publications|Tags: , |

J. Mater. Chem. A, 2017, Accepted ManuscriptDOI: 10.1039/C7TA06447K, PaperDong Wang, Xin Wang, Yue Lu, Changsheng Song, Jie Pan, Chilin Li, Manling Sui, Wei Zhao, Fu Qiang HuangNoble metal catalysts have extraordinary catalytic activity but suffer from high cost, therefore single atom catalysis attracts

Published in: "Journal of Materials Chemistry A".

Intercalating copper into layered TaS2 van der Waals gaps

2017-10-03T10:29:03+00:00 October 3rd, 2017|Categories: Publications|Tags: , |

RSC Adv., 2017, 7,46699-46703DOI: 10.1039/C7RA08630J, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Rui Liu, Cong Wang, Yuanyuan Li, Yong Xie, Qiang Chen, Ziyu Chen, Qian LiuAn efficient method to intercalate copper atoms into 2D layered

Published in: "RSC Advances".

Heat transport study of the spin liquid candidate 1T-TaS2. (arXiv:1706.08558v1 [cond-mat.str-el])

2017-06-28T13:25:33+00:00 June 28th, 2017|Categories: Publications|Tags: , |

We present the ultra-low-temperature thermal conductivity measurements on single crystals of the prototypical charge-density-wave material 1$T$-TaS$_2$, which was recently argued to be a candidate for quantum spin liquid. Our experiments show that the residual linear term of thermal conductivity at zero field is essentially zero, within the experimental accuracy. Furthermore, the thermal conductivity is found to be insensitive to the magnetic field up to 9 T. These results clearly demonstrate the absence of itinerant magnetic excitations with fermionic statistics in bulk 1$T$-TaS$_2$ and, thus, put a strong constraint on the theories of the ground state of this material.

Published in: "arXiv Material Science".

1T-TaS2 as a quantum spin liquid [Physics]

2017-06-20T17:14:04+00:00 June 20th, 2017|Categories: Publications|Tags: , |

1T-TaS2 is unique among transition metal dichalcogenides in that it is understood to be a correlation-driven insulator, where the unpaired electron in a 13-site cluster experiences enough correlation to form a Mott insulator. We argue, based on existing data, that this well-known material should be considered as a quantum spin…

Published in: "PNAS (Ahead)".

December 2015 Newsletter

2016-10-15T11:14:45+00:00 February 20th, 2016|Categories: Newsletters|Tags: , , , , |

Newsletter from 2D Research

 Most popular 2D articles

 

• Materials: Boron made into 2D sheet
by Editorial commentary Nature

An article from Nature highlighting a recent work published in Angewandte, demonstrating the growth of atomically thin boron films. The synthesis of boron seems to me an emerging area of science, with 3 other papers put online in December (Two on arXiv (1,2) and one published in Science).

This Angewandte article was also covered by a 2D Research editorial.

• Evidence for two dimensional Ising superconductivity in gated MoS2.
by Lu  et al, Science

Ionic-liquid gated molybdenum disulphide shows evidence of an Ising superconductor.

• Recent advances in two dimensional materials beyond graphene
by Bhimanapatiet al, ACS Nano

A review articles by scientists from more 10 different institutions providing experimental and theoretical insights on the properties of two dimensional materials beyond graphene.

• Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu-Ni alloys
by Wu  et al, Nature Materials

Self-explained title: an optimized copper nickel alloy shows improved ability to decrease the nucleation density of carbon in order to create large 1.5-inch single crystals of graphene, with reduced synthesis time.

• 1T-TaS2 in the two-dimensional limit
by Tsen  et al, PNAS

Hexagonal boron nitride encapsulated 1T tantalum disulphide enables the characterization of this material in the 2D limit and that the

January 2016 Newsletter

2016-10-15T11:14:45+00:00 February 20th, 2016|Categories: Newsletters|Tags: , , , , , |

Newsletter from 2D Research

MOST POPULAR ARTICLES

•  The observation of square ice in graphene questioned
by Zhou et al, Nature

Writing in Nature Zhou et al. question the previous Nature letter which presented evidence of two-dimensional square ice, trapped between two graphene layers. Their main evidence is two-fold. Firstly, they show that sodium chloride crystallizes in a structure akin to that presented in the initial article, and secondly show through simulations that the structure of a graphene-confined 2D ice does not have a perfectly square structure, rather a rhombic one.

In two accompanying replies to above, the authors of the initial paper still maintain that square ice can indeed be formed, since some of the features of the oxygen peaks do agree with recent theory work, although they do conclude that high resolution electron energy loss spectra looking for salts would unambiguously prove or disprove the contamination hypothesis. On the simulation front, the team shows that the rhomic, zig-zag structure is meta-stable, decaying into a square one in a matter of tens of nano-seconds, hence experimentally the lattice of ice will indeed show a square one.

• Evidence for two dimensional Ising superconductivity in gated MoS2.
by Lu al, Science

Ionic-liquid gated molybdenum disulphide shows evidence of an Ising superconductor.

• Recent advances in two dimensional materials beyond graphene
by Bhimanapati et al, 

Performances of Liquid-Exfoliated Transition Metal Dichalcogenides as Hole Injection Layers in Organic Light-Emitting Diodes

2016-10-15T11:44:05+00:00 June 15th, 2015|Categories: Publications|Tags: , , , |

By Cheolmin Kim, Thang Phan Nguyen, Quyet Van Le, Jong-Myeong Jeon, Ho Won Jang, Soo Young Kim 2D transition metal dichalcogenide (TMD) nanosheets, including MoS2, WS2, and TaS2, are used as hole injection layers (HILs) in organic light-emitting diodes (OLEDs). MoS2, WS2, and TaS2 nanosheets are prepared using an exfoliation by ultrasonication method. The thicknesses and sizes of the TMD nanosheets are measured to be 3.1–4.3 nm …read more

Published in: Advanced Functional Materials

Spin polarization driven by a charge-density wave in monolayer 1T-TaS2

2016-10-15T13:03:16+00:00 August 6th, 2014|Categories: Publications|Tags: , |

By Qingyun Zhang, Li-Yong Gan, Yingchun Cheng, and Udo Schwingenschlögl

Author(s): Qingyun Zhang, Li-Yong Gan, Yingchun Cheng, and Udo Schwingenschlögl

Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer T-phase TaS2. We demonstrate that a charge-density wave is energetically favorable at low temperature, similar to bulk 1T-TaS2. Electron-phonon coupling is found to be essential for the lattice…

[Phys. Rev. B 90, 081103] Published Wed Aug 06, 2014

…read more

Via: Physical Review B

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