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            PdBi half-Heusler semimetals: A new family of noncentrosymmetric magnetic superconductors

Nakajima, Yasuyuki; Hu, Rongwei; Kirshenbaum, Kevin; Hughes, Alex J.; Syers, Paul; Wang, Xiangfeng; Wang, Kenfeng; Wang, Renxiong; Saha, Shanta; Pratt, Dan E.; Lynn, J. W.; Paglione, Johnpierre

doi:10.1126/sciadv.1500242

Cited by 208 publications

(219 citation statements)

References 41 publications

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“…3). These Néel temperatures are close to those reported in the literature [9,10,13]. An antiferromagnetic ground state was found also for ErPdBi below 1.2 K [18] (T N = 1.06 K was reported in Ref.…”

Section: Resultssupporting

confidence: 91%

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Magnetic and Transport Properties of Possibly Topologically Nontrivial Half-Heusler Bismuthides RMBi (R = Y, Gd, Dy, Ho, Lu; M = Pd, Pt)

2016

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High quality single crystals of some representatives of half-Heusler family were grown from Bi-flux. For single crystals characterization, X-ray diffraction and scanning electron microscopy techniques were used. The lowtemperature physical properties of the synthesized crystals were determined by means of magnetization, magnetic susceptibility, electrical resistivity and heat capacity measurements. For each compound but LuPtBi, the electrical resistivity varies in a semimetallic manner at high temperatures, and exhibits a metallic character at low temperatures. LuPtBi is metallic in the whole temperature range studied. The bismuthides HoPdBi, LuPdBi, LuPtBi and YPtBi were found superconducting below the critical temperature Tc = 0.7, 1.8, 0.9, and 0.96 K, respectively. For the compounds GdPdBi, DyPdBi and HoPdBi, an antiferromagnetic ordering was found to set in below TN = 12.8, 3.7, and 1.9 K, respectively. HoPdBi is thus an intriguing material in which both cooperative phenomena coexist.

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Section: Resultssupporting

confidence: 91%

“…Only LuPtBi shows a metallic-like conductivity in the whole temperature range inspected. The overall behaviors of ρ(T ) are similar to those reported for poly- [9] and single-crystalline [6,[10][11][12][13] samples.…”

Section: Resultssupporting

confidence: 79%

Magnetic and Transport Properties of Possibly Topologically Nontrivial Half-Heusler Bismuthides RMBi (R = Y, Gd, Dy, Ho, Lu; M = Pd, Pt)

2016

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“…Some compounds from this class were found to be superconductors with critical temperatures up to 1.8 K, e.g. LaPtBi, LuPtBi, LuPdBi, YPtBi, YPdBi [8][9][10][11][12]. Compounds of the type RPdBi (R is a lanthanide with an open 4f shell) that show coexisiting local moment antiferromagnetism as well as superconductivity were found, pointing to the presence of spin triplet Cooper pairs [12], which is allowed due to the missing structural inversion symmetry [13].…”

mentioning

confidence: 99%

Unconventional Superconductivity in YPtBi and Related Topological Semimetals

Meinert

2016

Phys. Rev. Lett.

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YPtBi, a topological semimetal with very low carrier density, was recently found to be superconducting below Tc = 0.77 K. In the conventional theory, the nearly vanishing density of states around the Fermi level would imply a vanishing electron-phonon coupling and would therefore not allow for superconductivity. Based on relativistic density functional theory calculations of the electron-phonon coupling in YPtBi it is found that carrier concentrations of more than 10 21 cm −3are required to explain the observed critical temperature with the conventional pairing mechanism, which is several orders of magnitude larger than experimentally observed. It is very likely that an unconventional pairing mechanism is responsible for the superconductivity in YPtBi and related topological semimetals with the Half-Heusler structure.A series of Half-Heusler compounds with heavy elements were predicted to have topologically non-trivial band order [1][2][3]. These compound have high cubic symmetry, however without inversion symmetry. The normal band order with the s-like, twofold degenerate Γ 6 state sitting above the p-like, fourfold degenerate Γ 8 -state is inverted in some of these compounds due to spin-orbit coupling. In their natural state, the cubic symmetry leads to a band degeneracy at Γ around the Fermi level, rendering them semimetals with topologically non-trivial band order (topological semimetals) and very low density of states (DOS) at the Fermi level D(E F ). By breaking the cubic symmetry with some amount of uniaxial strain, the compounds can be made insulating, so they could become 3D topological insulators [4]. They would exhibit metallic surface states with Dirac-like dispersion, i.e., the electrons behave as massless particles with ultrahigh mobility, while at the same time being insulating in the bulk. These surface states are topologically protected as long as time-reversal symmetry is preserved, i.e., they are protected against scattering from non-magnetic impurities. Indeed, for some of these materials there is experimental evidence for topologically nontrivial bandstructures and the presence of Dirac surface states [5][6][7], although none were found to be insulating in the bulk. Some compounds from this class were found to be superconductors with critical temperatures up to 1.8 K, e.g. LaPtBi, LuPtBi, LuPdBi, YPtBi,. Compounds of the type RPdBi (R is a lanthanide with an open 4f shell) that show coexisiting local moment antiferromagnetism as well as superconductivity were found, pointing to the presence of spin triplet Cooper pairs [12], which is allowed due to the missing structural inversion symmetry [13]. Due to the topologically nontrivial band structure, novel collective excitations are possible, in particular surface Majorana fermions [14]. These could provide the basis for low-decoherence quantum processing [15].Superconducting semiconductors such as GeTe and SnTe are long known [16,17] and their superconductivity can be explained [17] with the Eliashberg theory of electron-phonon mediated superc...

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“…The crystal structure of half-Heusler materials is shown in Fig.1a, in which X and Z atoms form the NaCl-type substructure and Y and Z atoms form the zinc-blende substructure. For certain half-Heusler materials with AFM, including GdPtBi, DyPdBi, HoPdBi and TbPdBi 52,54,55 , magnetic moments come from the X atom and align ferromagnetically in one layer perpendicular to (111) direction and anti-ferromagnetically between two adjacent layers (type-G anti-ferromagnetic ordering), as shown in Fig.1b, while the exact direction of magnetic moments is still not clear and may depend on detailed compound composition.…”

Section: Model Hamiltonian Of Anti-ferromagnetic Half-heusler Matmentioning

confidence: 99%

“…Our interest in this work is focused on possible topological states in half-Heusler materials with AFM at zero external magnetic field. AFM has been experimentally observed in RPdBi (R = Er, Ho, Gd, Dy, Tb, Nd) and GdPtBi [50][51][52][53][54][55][56] , with Neel temperature ranging from 1K to 13K. To describe AFM in half-Heusler compounds, we construct a generalized six-band Kane model with anti-ferromagnetic coupling terms based on the symmetry principle and justify this model with the microscopic tight-binding model.…”

Section: Introductionmentioning

confidence: 99%

Model Hamiltonian and time reversal breaking topological phases of antiferromagnetic half-Heusler materials

Yan

Liu

2017

Phys. Rev. B

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In this work, we construct a generalized Kane model with a new coupling term between itinerant electron spins and local magnetic moments of anti-ferromagnetic ordering in order to describe the low energy effective physics in a large family of anti-ferromagnetic half-Heusler materials. Topological properties of this generalized Kane model is studied and a large variety of topological phases, including Dirac semimetal phase, Weyl semimetal phase, nodal line semimetal phase, type-B triple point semimetal phase, topological mirror (or glide) insulating phase and anti-ferromagnetic topological insulating phase, are identified in different parameter regions of our effective models. In particular, we find that the system is always driven into the anti-ferromagnetic topological insulator phase once a bulk band gap is open, irrespective of the magnetic moment direction, thus providing a robust realization of anti-ferromagentic topological insulators. Furthermore, we discuss the possible realization of these topological phases in realistic anti-ferromagnetic half-Heusler materials. Our effective model provides a basis for the future study of physical phenomena in this class of materials.

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Topological R PdBi half-Heusler semimetals: A new family of noncentrosymmetric magnetic superconductors

Abstract: Tunable superconductivity and magnetism in noncentrosymmetric RPdBi provide a new route to exotic topological excitations.

Cited by 208 publications

References 41 publications

Magnetic and Transport Properties of Possibly Topologically Nontrivial Half-Heusler Bismuthides RMBi (R = Y, Gd, Dy, Ho, Lu; M = Pd, Pt)

Magnetic and Transport Properties of Possibly Topologically Nontrivial Half-Heusler Bismuthides RMBi (R = Y, Gd, Dy, Ho, Lu; M = Pd, Pt)

Unconventional Superconductivity in YPtBi and Related Topological Semimetals

Model Hamiltonian and time reversal breaking topological phases of antiferromagnetic half-Heusler materials

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