Electronic Structure and Thermoelectric Properties of Transition Metal Monosilicides

Pshenay-Severin, D. A.; Ivanov, Yu. V.; Бурков, А. Т.; Новиков, С. В.; Zaĭtsev, V. K.; Reith, Heiko

doi:10.1007/s11664-017-6005-8

Cited by 23 publications

(36 citation statements)

References 17 publications

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“…The cyclotron masses of α and β are fitted to be 1.2 m e and 1.3 m e in S xx and 0.94 and 0.95 in S xy , respectively. These cyclotron masses are much heavier than those of electrons observed in Weyl semimetal TaAs and TaP family [41,42,52], but close to previously reported effective masses of electrons (∼ 2 m e ) in CoSi [16,31]. The difference between cyclotron masses obtained from S xx and S xy deserves better understanding in the future.…”

Section: Resultssupporting

confidence: 83%

“…Tellurium was found to be an appropriate metal flux for the growth of CoSi which yields high-quality single crystals with large magneto-resistance (MR) and carrier mobilities. Although there is plenty of research work on the thermopower of CoSi [16][17][18][19][20][21][28][29][30][31][32], few of them have paid attention to its magneto-Seebeck and Nernst effect.…”

Section: Introductionmentioning

confidence: 99%

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Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

Wang

Cochran

et al. 2019

Phys. Rev. B

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We survey the electrical transport properties of the single-crystalline, topological chiral semimetal CoSi which was grown via different methods. High-quality CoSi single crystals were found in the growth from tellurium solution. The sample's high carrier mobility enables us to observe, for the first time, quantum oscillations (QOs) in its thermoelectrical signals. Our analysis of QOs reveals two spherical Fermi surfaces around the R point in the Brillouin zone corner. The extracted Berry phases of these electron orbits are consistent with the −2 chiral charge as reported in DFT calculations. Detailed analysis on the QOs reveals that the spin-orbit coupling induced band-splitting is less than 2 meV near the Fermi level, one order of magnitude smaller than our DFT calculation result. We also report the phonon-drag induced large Nernst effect in CoSi at intermediate temperatures.

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Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

Wang

Cochran

et al. 2019

Phys. Rev. B

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“…The calculations were performed on 8 × 8 × 8 Monhorst-Pack mesh with 350 eV cutoff energy. In agreement with [8,6,7,11,14] we find that the states near the Fermi energy are located near the Γ, M and R points in the BZ (see Fig. 1).…”

Section: Electronic Structure Of Cobalt Monosilicide Without G 0 W 0 supporting

confidence: 91%

Band structure and unconventional electronic topology of CoSi

Pshenay-Severin

Ivanov

Burkov

et al. 2018

J. Phys.: Condens. Matter

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Semimetals with certain crystal symmetries may possess unusual electronic structure topology, distinct from that of the conventional Weyl and Dirac semimetals. Characteristic property of these materials is the existence of band-touching points with multiple (higher than two-fold) degeneracy and nonzero Chern number. CoSi is a representative of this group of materials exhibiting the so-called 'new fermions'. We report on an ab initio calculation of the electronic structure of CoSi using density functional methods, taking into account the spin-orbit interactions. The linearized [Formula: see text] Hamiltonian, describing the anisotropic electronic structure of CoSi near the Γ point is derived. The topological features of band-touching nodes with four- and six-fold degeneracy located at the Γ and R points in the first Brillouin zone are analysed using the linearized Hamiltonians and first principle calculations. In particular, we show, using the non-Abelian Berry curvature, that these band-touching points carry topological charges of [Formula: see text], which change signs at certain values of parameters of the Hamiltonians. We describe the resulting Fermi arc surface states and their spin texture. We also discuss the influence of many body [Formula: see text] corrections on the electronic band structure and the topological properties of CoSi.

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“…In contrast, the fermionic materials host Weyl fermions that are degenerated and carry a higher chiral charge. [5,8,9] Interestingly, related silicides like MnSi, [10] Fe 0.75 Co 0.25 Si [11] and germanides like Fe 1 −x Co x Ge [12,13] also feature skyrmion states.In general, Weyl materials show characteristic quantum effects in the transport, resulting for example in quantum Materials with topological electronic states have emerged as one of the most exciting discoveries of condensed quantum matter, hosting quasiparticles with extremely low effective mass and high mobility. The chiral charge of the material strongly depends on the space group of the crystal structure.…”

mentioning

confidence: 99%

“…CoSi has a cubic B20 crystal structure (space group 198 P2 1 3) with broken space inversion symmetry. [5,8,9] Interestingly, related silicides like MnSi, [10] Fe 0.75 Co 0.25 Si [11] and germanides like Fe 1 −x Co x Ge [12,13] also feature skyrmion states. [4] In CoSi, the Weyl fermions carry a chiral charge of up to ±4.…”

mentioning

confidence: 99%

Signatures of a Charge Density Wave Phase and the Chiral Anomaly in the Fermionic Material Cobalt Monosilicide CoSi

Schnatmann

Geishendorf

Lammel

et al. 2019

Adv Elect Materials

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to the emerging class of materials with non-trivial electronic band structure like topological insulators, Dirac or Weyl materials, featuring different topologically protected electronic states. In Weyl materials, these topologically protected electronic states are highly stable quasiparticles in the bulk, known as Weyl fermions, that were first predicted by Hermann Weyl in 1929. [1] These Weyl fermions carry a non-zero chiral charge and always appear in pairs. In a common Weyl material, this chiral charge is ±1; hence, the total chiral charge is zero. In contrast, the fermionic materials host Weyl fermions that are degenerated and carry a higher chiral charge. Remarkably, recently long Fermi arcs were observed in the fermionic material CoSi by Rao et al. [2] Also, Sanchez et al. [3] discovered helicoid-arc quantum states in CoSi.A necessary condition for the existence of Weyl fermions is a broken space or time inversion symmetry. The chiral charge of the material strongly depends on the space group of the crystal structure. CoSi has a cubic B20 crystal structure (space group 198 P2 1 3) with broken space inversion symmetry. This space group was predicted to host sixfold degenerated Weyl fermions. [4] In CoSi, the Weyl fermions carry a chiral charge of up to ±4. In detail, spin 1 excitations with a chiral charge of ±2 and spin 3/2 excitations with a chiral charge of ±4 (Rarita-Schwinger-Weyl fermions) were predicted. [5,6] Electrical transport experiments are a powerful tool to probe the energy spectrum of a material and thereby the specific nature of Weyl fermions. Topological states are massless due to the linear dispersion relation, and thus have an extremely high mobility. While often superimposed by the normal band transport, contributions of the Weyl fermions increase the total electrical conductivity. Consequently, the emerging class of materials with non-trivial electronic band structure has a large overlap with other classes of functional materials like the class of thermoelectric materials. [7] This also holds for CoSi. [5,8,9] Interestingly, related silicides like MnSi, [10] Fe 0.75 Co 0.25 Si [11] and germanides like Fe 1 −x Co x Ge [12,13] also feature skyrmion states.In general, Weyl materials show characteristic quantum effects in the transport, resulting for example in quantum Materials with topological electronic states have emerged as one of the most exciting discoveries of condensed quantum matter, hosting quasiparticles with extremely low effective mass and high mobility. Weyl materials contain such topological states in the bulk and additionally have a non-trivial chiral charge. However, despite known quantum effects caused by these chiral states, the interplay between chiral states, and a charge density wave phase, an ordering of the electrons to a correlated phase is not experimentally explored. Indications for the formation of a charge density wave phase in the Weyl material cobalt monosilicide CoSi are observed. Furthermore, the typical signatures of the charge density wave phase together...

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Electronic Structure and Thermoelectric Properties of Transition Metal Monosilicides

Cited by 23 publications

References 17 publications

Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

Band structure and unconventional electronic topology of CoSi

Signatures of a Charge Density Wave Phase and the Chiral Anomaly in the Fermionic Material Cobalt Monosilicide CoSi

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