Manipulation of type-I and type-II Dirac points in 
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 superconductor by external pressure

Xiao, Rui-Chun; Gong, Penglai; Wu, Quansheng; Lu, W. J.; Wei, Mingming; Li, Jinya; Lv, Huiying; Luo, X.; Tong, P.; Zhu, Xuebin; Sun, Young

doi:10.1103/physrevb.96.075101

Cited by 70 publications

(62 citation statements)

References 72 publications

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“…Additionally, superconductivity was observed in NiTe 2 under pressure [53] and with the intercalation of Ti into the van der Waals gap (the space between two adjacent chalcogenide layers) [50], and was also predicted in atomically thin systems [54]. Moreover, the energy position of its Dirac node, closer to the Fermi level when compared with similar systems [42,55,56], combined with accessible high-quality single crystals [57][58][59] substantiate the interest on the material.…”

Section: Introductionsupporting

confidence: 53%

“…While Dirac type-I semimetals exhibit a negative magnetoresistance in all directions [15,17], the transport properties in Dirac type-II semimetals are expected to be anisotropic and present a negative magnetoresistance only in directions where the potential component of the energy spectrum is higher than the kinetic component [38]. PdTe 2 [56] and the family of compounds CaAgBi [91] are the few materials in which the coexistence of Dirac cones of type-I and type-II is expected to occur in the same pair of bands. However, the type-II Dirac node on NiTe 2 is much closer to the Fermi level, and, also, their momentum separation is smaller, providing a better platform to investigate interaction between quasiparticles with different pseudorelativistic signatures.…”

Section: B Dynamically Controlling the Dirac Conementioning

confidence: 99%

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Strain engineering the topological type-II Dirac semimetal NiTe2

et al. 2021

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In the present work, we investigate the electronic and elastic properties in equilibrium and under strain of the type-II Dirac semimetal NiTe 2 using density functional theory. Our results demonstrate the tunability of Dirac nodes' energy and momentum with strain and that it is possible to bring them closer to the Fermi level, while other metallic bands are suppressed. We also derive a minimal 4-band effective model for the Dirac cones, which accounts for the aforementioned strain effects by means of lattice regularization, providing an inexpensive way for further theoretical investigations and easy comparison with experiments. On an equal footing, we propose the static control of the electronic structure by intercalating alkali species into the van der Waals gap, resulting in the same effects obtained by strain engineering and removing the requirement of in situ strain. Finally, evaluating the wave-function's symmetry evolution as the lattice is deformed, we discuss possible consequences, such as Liftshitz transitions and the coexistence of type-I and type-II Dirac cones, thus motivating future investigations.

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Section: Introductionsupporting

confidence: 53%

Section: B Dynamically Controlling the Dirac Conementioning

confidence: 99%

Strain engineering the topological type-II Dirac semimetal NiTe2

et al. 2021

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“…Stress is also considered to drive topological phase transitions and understand the nature of topological states in PtTe 2 and PdTe 2 . Sun and co‐workers reported that the type‐II and type‐I Dirac points of PdTe 2 can be tuned by external pressure, where the type‐II Dirac points disappears at 6.1 GPa, and the new type‐I Dirac points emerges at 4.7 GPa . Doping is also a direct method to tune the band structure of NTMDs.…”

Section: Structure Of 2d Ntmdsmentioning

confidence: 99%

Recent Progress on 2D Noble‐Transition‐Metal Dichalcogenides

Liu

et al. 2019

Adv Funct Materials

223

166

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Emerging classes of 2D noble-transition-metal dichalcogenides (NTMDs) stand out for their unique structure and novel physical properties in recent years. With the nearly full occupation of the d orbitals, 2D NTMDs are expected to be more attractive due to the unique interlayer vibrational behaviors and largely tunable electronic structures compared to most transition metal dichalcogenide semiconductors. The novel properties of 2D NTMDs have stimulated various applications in electronics, optoelectronics, catalysis, and sensors. Here, the latest development of 2D NTMDs are reviewed from the perspective of structure characterization, preparation, and application. Based on the recent research, the conclusions and outlook for these rising 2D NTMDs are presented.Very recently, group-10 noble TMDs (NTMDs) have been reintroduced as new 2D materials, displaying many fascinating properties including widely tunable bandgap, moderate carrier mobility, anisotropy, and ultrahigh air stability. [34][35][36][37] Unlike most common TMDs with less d-electrons, the d orbitals of NTMDs are nearly fully occupied, and the corresponding p z orbital of interlayer chalcogen atoms are highly hybridized, leading to strong layer-dependent properties and interlayer interactions. [36,38] For example, it has been predicted that PtS 2 holds a layerdependent bandgap from 0.25 to 1.6 eV, [36] bridging the gap between graphene and most TMDs that with large gap. Besides, the calculated mobility based on PtS 2 , PtSe 2 , and PdSe 2 field effect transistors (FETs) is as high as ≈200 cm 2 V −1 s −1 , [36,37,39] larger than most other TMDs. Moreover, NTMDs possess high air stability, and the performance of the PtSe 2 FET remains nearly unchanged after 5 months air exposure. [37] Specially, PdS 2 and PdSe 2 hold novel puckered pentagonal structure and thus exhibit very interesting anisotropic properties, [39,40] which may bring even more physics and applications. Additionally, PtTe 2 and PdTe 2 are type-II Dirac fermions, making them great platform for investigating novel transport related to topological phase transition and chiral anomaly. [41,42] Nowadays, the 2D NTMDs is becoming increasingly fascinating in the 2D materials research.In this review, we highlight a comprehensive report of the recent research progress in 2D NTMDs such as PtS 2 , PtSe 2 , PdS 2 , PdSe 2 , PtTe 2 , and PdTe 2 . In order to understand the internal relation between structural characteristics and physical properties, this review begins with a brief summary of the structure of 2D NTMDs and their transitions. Then, some recent progress on their preparation methods, including mechanical exfoliation of the bulk materials, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), is reviewed along with the performance of the resulting 2D NTMDs as high-performance candidate for field effect transistors, photodetectors, catalysis, and sensors. Finally, this review is concluded with the existing challenges and a future perspective for these rising 2D NTMDs. Structure of 2D NTM...

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“…More recently, the transition metal dichalcogenides (TMDs) TMX 2 (TM=Pd, Pt; X=Se, Te) were proposed to host type-II Dirac fermions and were soon verified in angle-resolved photoemission spectroscopy (ARPES) experiments. [17][18][19][20][21][22][23][24][25][26][27][28] Interestingly, PdTe 2 also superconducts below T c =2 K and the Au substitution can boost T c to a maximum value of 4.7 K, making this family of TMDs a promising platform to search for topological superconductors. [29][30][31][32][33][34] However, the Dirac points reported in these materials are located deeply below the Fermi level, with a binding energy of 0.6 eV in PdTe 2 , 0.8 eV in PtTe 2 , and 1.2 eV in PtSe 2 .…”

Section: Introductionmentioning

confidence: 99%

Topological Type-II Dirac Fermions Approaching the Fermi Level in a Transition Metal Dichalcogenide NiTe₂

et al. 2018

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Type-II Dirac/Weyl semimetals are characterized by strongly tilted Dirac cones such that the Dirac/Weyl node emerges at the boundary of electron and hole pockets as a new state of quantum matter, distinct from the standard Dirac/Weyl points with a point-like Fermi surface which are referred to as type-I nodes. The type-II Dirac fermions were recently predicted by theory and have since been confirmed in experiments in the PtSe 2 -class of transition metal dichalcogenides. However, the Dirac nodes observed in PtSe 2 , PdTe 2 and PtTe 2 candidates are quite far away from the Fermi level, making the signature of topological fermions obscure as the physical properties are still dominated by the non-Dirac quasiparticles. Here we report the synthesis of a new type-II Dirac semimetal NiTe 2 in which a pair of type-II Dirac nodes are located very close to the Fermi level. The quantum oscillations in this material reveal a nontrivial Berry's phase associated with these Dirac fermions. Our first principles calculations further unveil a topological Dirac cone in its surface states. Therefore, NiTe 2 may not only represent an improved system to formulate the theoretical understanding of the exotic consequences of type-II Dirac fermions, it also facilitates possible applications based on these topological carriers.

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Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Cited by 70 publications

References 72 publications

Strain engineering the topological type-II Dirac semimetal NiTe2

Strain engineering the topological type-II Dirac semimetal NiTe2

Recent Progress on 2D Noble‐Transition‐Metal Dichalcogenides

Topological Type-II Dirac Fermions Approaching the Fermi Level in a Transition Metal Dichalcogenide NiTe₂

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Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Cited by 70 publications

References 72 publications

Strain engineering the topological type-II Dirac semimetal NiTe2

Strain engineering the topological type-II Dirac semimetal NiTe2

Recent Progress on 2D Noble‐Transition‐Metal Dichalcogenides

Topological Type-II Dirac Fermions Approaching the Fermi Level in a Transition Metal Dichalcogenide NiTe2

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Topological Type-II Dirac Fermions Approaching the Fermi Level in a Transition Metal Dichalcogenide NiTe₂