Bulk and surface electronic structure of hexagonal structured<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>PtBi</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>studied by angle-resolved photoemission spectroscopy

Yao, Qi; Du, Yulei; Yang, Xiaohui; Zheng, Yi; Xu, D. F.; Niu, X. H.; Shen, Xiaoping; Yang, Haifeng; Dudin, Pavel; Kim, T. K.; Hoesch, Moritz; Vobornik, I.; Xu, Z. A.; Wan, Xiangang; Feng, D. L.; Shen, Dawei

doi:10.1103/physrevb.94.235140

Cited by 19 publications

(16 citation statements)

References 31 publications

(29 reference statements)

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“…Thus, there are in total 6 Dirac cones of this type in a BZ. This observation is in good agreement with previous ARPES report on this compound [36]. The electronic structure of PtBi 2 seems to be cleavage dependent.…”

Section: (D) Figs 2(e)-(h) Depict Edms Measured Using Various Photosupporting

confidence: 93%

“…Thus, there exists 6 Dirac cones of this type in a Brillouin zone. This observation is consistent with a previous ARPES report [36] on this compound. Interestingly, in addition to this, we have uncovered for the first time an another surface Dirac cone at the zone center with a node at ≈ 900 meV below E F .…”

supporting

confidence: 94%

“…Note here that the Fermi level of the calculated band structure is shifted about 200 meV towards the lower-binding energy to match with the experiment. A similar observation was also made in the previous ARPES report of this compound [36].…”

supporting

confidence: 89%

“…Previous transport [33] and ARPES studies [36] on this compound suggested crystal disorder for the observed linear magnetoresistance. On the other hand, our present studies clearly show two sets of linear dispersive Dirac states crossing the Fermi level with nodes located at around 150 meV and 900 meV below E F .…”

Section: (D) Figs 2(e)-(h) Depict Edms Measured Using Various Photomentioning

confidence: 59%

“…Therefore, understating the mechanism of extremely large MR in this compound is essential due to its potential applications. While in the pyrite structure the extremely large MR is attributed to its semimetalic nature [34], the large linear MR observed in the hexagonal phase is explained based on the crystal disorder theory [33,36]. Here, we report on the electronic structure of hexagonal PtBi 2 using the ARPES technique and first-principles calculations.…”

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confidence: 99%

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Possible origin of linear magnetoresistance: Observation of Dirac surface states in layered PtBi2

et al. 2018

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The nonmagnetic compounds showing extremely large magnetoresistance are attracting a great deal of research interests due to their potential applications in the field of spintronics. PtBi2 is one of such interesting compounds showing large linear magnetoresistance (MR) in its both the hexagonal and pyrite crystal structure. We use angle-resolved photoelectron spectroscopy (ARPES) and density functional theory (DFT) calculations to understand the mechanism of liner MR observed in the hexagonal PtBi2. Our results uncover for the first time linear dispersive surface Dirac states at theΓ-point, crossing Fermi level with node at a binding energy of ≈ 900 meV, in addition to the previously reported Dirac states at theM -point in the same compound. We further notice from our dichroic measurements that these surface states show an asymmetric spectral intensity when measured with left and right circularly polarized light, hinting at a substantial spin polarization of the bands. Following these observations, we suggest that the linear dispersive Dirac states at thē Γ andM -points are likely to play a crucial role for the linear field dependent magnetoresistance recorded in this compound. Bi [20] is explained based on the charge compensation [16]. However, the role of charge compensation for the XMR of these compounds is still not clear as some reports recently demonstrated quadratic field dependent MR without charge balance [21,22]. Moreover, the theory based on the impurity scattering or crystal disorder is inevitably brought into the above two cases and as well to the subquadratic field dependent MR [23][24][25]. The other existing mechanisms include metal-insulator transition [26][27][28][29][30] and strong spin-orbit interactions [31,32]. Thus, there is no clear consensus yet on the mechanism of magnetoresistance in the nonmagnetic solids.PtBi 2 is a very interesting compound as it shows MR in both the hexagonal [33] and pyrite structures [34]. Astonishingly, the pyrite PtBi 2 has been found to show the highest MR observed among the known nonmagnetic metals so far [4-7, 10, 16, 17], which also has been predicted as a 3-dimensional Dirac semimetal [35]. Therefore, understating the mechanism of extremely large MR in this compound is essential due to its potential applications. While in the pyrite structure the extremely large MR is attributed to its semimetalic nature [34], the large linear MR observed in the hexagonal phase is explained based on the crystal disorder theory [33,36]. Here, we report on the electronic structure of hexagonal PtBi 2 using the ARPES technique and first-principles calculations. Our studies suggest that PtBi 2 has two different surface terminations as the experimental band structure looks different from different cleavages. Our ARPES measurements demonstrate linear dispersive surface Dirac states near the Fermi level with a node at ≈ 150 meV below the Fermi level (E F ) at theM -point with a 6-fold rotational symmetry in the ΓM K plane. Thus, there exists 6 Dirac cones of this type in a Bril...

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Section: (D) Figs 2(e)-(h) Depict Edms Measured Using Various Photosupporting

confidence: 93%

supporting

confidence: 94%

supporting

confidence: 89%

Section: (D) Figs 2(e)-(h) Depict Edms Measured Using Various Photomentioning

confidence: 59%

mentioning

confidence: 99%

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Possible origin of linear magnetoresistance: Observation of Dirac surface states in layered PtBi2

et al. 2018

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Bismuth‐Noble Metal Alloy Nanostructures Prepared by Colloidal Chemical Routes for Use in Hydrogen Evolution and Oxygen Reduction Electrocatalysis: Bi‐Pt Versus Bi‐Pd

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et al. 2022

Advanced Sustainable Systems

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oxidation reaction. In addition, an alteration of the active adsorption sites due to dilution of the catalytically active material may also take place when bimetallic catalysts are employed. Bismuth has already received interest as a Pt-modifier for electrocatalytic use. In this way, the noble metal quantity (and thus the overall cost) can be reduced, while the catalytic activity can be maintained (or even improved) by replacing a certain Pt amount with a less expensive metal. Bi may also modify the electronic structure of the Pt by lowering its d-band center. [1] Pt-Bi has been reported to be CO tolerant and it has exhibited higher catalytic performance for several oxidation reactions such as methanol, glycerol, ethylene glycol, and ethanol. The lower poisoning of Pt-Bi catalysts with CO has been proposed to be a determinant factor for the increase in catalytic activity of such materials. [2] Another example of an electrochemical reaction in which a bimetallic system can perform better than its monometallic counterpart is the electro-oxidation of formic acid. Pt-Bi showed a more negative onset potential and higher current density than monometallic Pt, together with the above-mentioned high tolerance to CO. [3] For the Pt-Bi alloy system, the PtBi 2 composition possesses a layered hexagonal crystal structure and has been suggested to behave as a 3D topological semimetal with very high magnetoresistance and unique electronic structures. A good comprehension of the electronic structure of PtBi 2 is required to properly assign the actual origin of its anomalous transport properties. [4] Pt-Bi bimetallic structures have found applications in thermoelectronics and batteries. Pt-Bi 2 O 3 has been shown to facilitate the photolysis of water, while single Pt or Bi 2 O 3 were unable to catalyze such reactions on their own. Pt-Bi/AC (activated carbon) is a commercially available catalyst for electrocatalysis and selective oxidation reactions. It has been suggested that Bi causes a geometric blocking effect on Pt, thus decreasing the active site ensemble of Pt. These decreased sites will still permit certain desired chemical reactions to occur, but they will not be active for specific undesired side reactions. The electronic properties of Bi help to increase the electrocatalytic activity of Pt, inhibiting poison effects, thanks to its small electron effective mass, low carrier concentrations, and highly anisotropic Fermi surface. [5,6] Pt-Bi alloy may not be the most suitable electrocatalyst for the oxygen reduction reaction (ORR); [7] still, though Pt-Bi catalysts Compositional and morphological tuning of bismuth-based nanomaterials is crucial to improve and broaden the application of such structures in a range of electrocatalytic reactions. Nanostructures composed of Pt-Bi and Pd-Bi alloys in different elemental proportions and shapes are produced by solvothermal and hydrothermal chemical routes at moderate temperatures. The alloying of cost-effective bismuth with platinum is found to be much more efficient than that with...

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Terahertz wave emission from the trigonal layered PtBi2

et al. 2022

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Bulk and surface electronic structure of hexagonal structuredPtBi2studied by angle-resolved photoemission spectroscopy

Cited by 19 publications

References 31 publications

Possible origin of linear magnetoresistance: Observation of Dirac surface states in layered PtBi2

Possible origin of linear magnetoresistance: Observation of Dirac surface states in layered PtBi2

Bismuth‐Noble Metal Alloy Nanostructures Prepared by Colloidal Chemical Routes for Use in Hydrogen Evolution and Oxygen Reduction Electrocatalysis: Bi‐Pt Versus Bi‐Pd

Terahertz wave emission from the trigonal layered PtBi2

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