Phonons in bulk and monolayer HfS2 and possibility of phonon-mediated superconductivity: A first-principles study

Chen, Jianyong

doi:10.1016/j.ssc.2016.03.021

Cited by 30 publications

(19 citation statements)

References 41 publications

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“…Infrared and Raman activities are not compatible because the crystal structure has a center of inversion symmetry (and one of the modes for each of the u -symmetries correspond to acoustic modes). The atomic displacements for the optical modes can be found in previous works 15 , 17 , 19 .…”

Section: Resultsmentioning

confidence: 99%

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High-pressure Raman scattering in bulk HfS2: comparison of density functional theory methods in layered MS2 compounds (M = Hf, Mo) under compression

Ibáñez

Woźniak

Dybała

et al. 2018

Sci Rep

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We report high-pressure Raman-scattering measurements on the transition-metal dichalcogenide (TMDC) compound HfS2. The aim of this work is twofold: (i) to investigate the high-pressure behavior of the zone-center optical phonon modes of HfS2 and experimentally determine the linear pressure coefficients and mode Grüneisen parameters of this material; (ii) to test the validity of different density functional theory (DFT) approaches in order to predict the lattice-dynamical properties of HfS2 under pressure. For this purpose, the experimental results are compared with the results of DFT calculations performed with different functionals, with and without Van der Waals (vdW) interaction. We find that DFT calculations within the generalized gradient approximation (GGA) properly describe the high-pressure lattice dynamics of HfS2 when vdW interactions are taken into account. In contrast, we show that DFT within the local density approximation (LDA), which is widely used to predict structural and vibrational properties at ambient conditions in 2D compounds, fails to reproduce the behavior of HfS2 under compression. Similar conclusions are reached in the case of MoS2. This suggests that large errors may be introduced if the compressibility and Grüneisen parameters of bulk TMDCs are calculated with bare DFT-LDA. Therefore, the validity of different approaches to calculate the structural and vibrational properties of bulk and few-layered vdW materials under compression should be carefully assessed.

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Section: Resultsmentioning

confidence: 99%

“…First-principle calculations have recently shown that, contrary to bulk HfS 2 , its monolayer form exhibits a phononic gap which can be tailored by applying biaxial strain 15 . So far, however, the high-pressure effects on the vibrational properties of bulk HfS 2 have been investigated neither theoretically nor experimentally.…”

Section: Introductionmentioning

confidence: 99%

High-pressure Raman scattering in bulk HfS2: comparison of density functional theory methods in layered MS2 compounds (M = Hf, Mo) under compression

Ibáñez

Woźniak

Dybała

et al. 2018

Sci Rep

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“…In addition, ultrathin HfS 2 not only shows faster and higher response, but also higher stability in comparison to most of the other 2D materials, which makes HfS 2 an appropriate positional candidate for the electronic and optoelectronic applications [7,26].…”

Section: Introductionmentioning

confidence: 99%

A First-Principles Study of Nonlinear Elastic Behavior and Anisotropic Electronic Properties of Two-Dimensional HfS2

et al. 2020

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We utilize first principles calculations to investigate the mechanical properties and strain-dependent electronic band structure of the hexagonal phase of two dimensional (2D) HfS2. We apply three different deformation modes within −10% to 30% range of two uniaxial (D1, D2) and one biaxial (D3) strains along x, y, and x-y directions, respectively. The harmonic regions are identified in each deformation mode. The ultimate stress for D1, D2, and D3 deformations is obtained as 0.037, 0.038 and 0.044 (eV/Ang3), respectively. Additionally, the ultimate strain for D1, D2, and D3 deformation is obtained as 17.2, 17.51, and 21.17 (eV/Ang3), respectively. In the next step, we determine the second-, third-, and fourth-order elastic constants and the electronic properties of both unstrained and strained HfS2 monolayers are investigated. Our findings reveal that the unstrained HfS2 monolayer is a semiconductor with an indirect bandgap of 1.12 eV. We then tune the bandgap of HfS2 with strain engineering. Our findings reveal how to tune and control the electronic properties of HfS2 monolayer with strain engineering, and make it a potential candidate for a wide range of applications including photovoltaics, electronics and optoelectronics.

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“…2d inset. First-principle studies have shown that the peak corresponding to the Raman-active A 1g phonon mode of HfS 2 downshifts (upshifts) with the application of tensile (compressive) strain 23 . In Fig.…”

Section: Resultsmentioning

confidence: 99%

Strain-engineered inverse charge-funnelling in layered semiconductors

et al. 2018

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The control of charges in a circuit due to an external electric field is ubiquitous to the exchange, storage and manipulation of information in a wide range of applications. Conversely, the ability to grow clean interfaces between materials has been a stepping stone for engineering built-in electric fields largely exploited in modern photovoltaics and opto-electronics. The emergence of atomically thin semiconductors is now enabling new ways to attain electric fields and unveil novel charge transport mechanisms. Here, we report the first direct electrical observation of the inverse charge-funnel effect enabled by deterministic and spatially resolved strain-induced electric fields in a thin sheet of HfS2. We demonstrate that charges driven by these spatially varying electric fields in the channel of a phototransistor lead to a 350% enhancement in the responsivity. These findings could enable the informed design of highly efficient photovoltaic cells.

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Phonons in bulk and monolayer HfS2 and possibility of phonon-mediated superconductivity: A first-principles study

Cited by 30 publications

References 41 publications

High-pressure Raman scattering in bulk HfS2: comparison of density functional theory methods in layered MS2 compounds (M = Hf, Mo) under compression

High-pressure Raman scattering in bulk HfS2: comparison of density functional theory methods in layered MS2 compounds (M = Hf, Mo) under compression

A First-Principles Study of Nonlinear Elastic Behavior and Anisotropic Electronic Properties of Two-Dimensional HfS2

Strain-engineered inverse charge-funnelling in layered semiconductors

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