Superconductivity in Germanium Telluride

Hein, R. A.; Gibson, John W.; Mazelsky, R.; Miller, R. C.; Hülm, J. K.

doi:10.1103/physrevlett.12.320

Cited by 154 publications

(70 citation statements)

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“…In semiconductors, an insulator-to-metal transition takes place when the dopant-induced carrier concentration increases a certain level. Moreover, superconductivity has been experimentally achieved in some semiconductors at very low temperatures [21][22][23][24] following the theoretical predictions by Gurevich et al [25] and Cohen [26]. Recently, the semiconductor-to-metal transition has been realized in n-type N-doped 4H-SiC with carrier concentration above 10 19 cm…”

Section: Introductionmentioning

confidence: 91%

Superconductivity in carrier-doped silicon carbide

Muranaka

Kikuchi

Yoshizawa

et al. 2008

Science and Technology of Advanced Materials

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We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature T c = 1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al) shows type-II superconductivity with T c = 1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below T c with effective hole-carrier concentration n higher than 10 20 cm −3 . We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

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Section: Introductionmentioning

confidence: 91%

Superconductivity in carrier-doped silicon carbide

Muranaka

Kikuchi

Yoshizawa

et al. 2008

Science and Technology of Advanced Materials

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“…Superconductivity was observed subsequently in reduced SrTiO 3 perovskite single crystals [20,21] and in Ge 1-x Te alloys [22] . However, the interest in superconducting dopedsemiconductors did not last, probably because of the low critical temperatures (at most 0.5K [21] ).…”

Section: ) Superconducting Semiconductors : From Early Predictions Tmentioning

confidence: 99%

Superconducting group-IV semiconductors

et al. 2009

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We present recent achievements and predictions in the field of doping-induced superconductivity in column IV-based covalent semiconductors, with a focus on Bdoped diamond and silicon. Despite the amount of experimental and theoretical work produced over the last four years, many open questions and puzzling results remain to be clarified. The nature of the coupling (electronic correlation and/or phonon-mediated), the relationship between the doping concentration and the critical temperature (T C ), which determines the prospects for higher transition temperatures, as well as the influence of disorder and dopant homogeneity, are debated issues that will determine the future of the field. We suggest that innovative superconducting devices, combining specific properties of diamond or silicon, and the maturity of semiconductor-based technologies, will soon be developed. 1) IntroductionIt was probably the discovery of a superconducting transition around 40 K in the rather simple MgB 2 compound [1] that revived the interest for a specific class of superconducting materials, belonging to the so-called covalent metals [2] . These superconducting covalent systems (see box 1), including B-doped diamond [3] , silicon [4] , and silicon carbide [5,6] , Ba-doped silicon clathrates [7,8] , alkali-doped fullerenes [9,10] and the CaC 6 or YbC 6 intercalated graphites [11,12] , share the specificity of involving at least one relatively light element and of preserving strongly directional covalent bonds in their metallic state. The implications of this covalent character are important in superconductors in which Cooper pairs are coupled through phonons. The use of perturbation theory to study the renormalisation of the electron-electron repulsion by the electron-phonon interaction leads to the so-called Eliashberg equations [13] and to the celebrated McMillan formula [13] relating, in an approximate way, the superconducting transition temperature T C to an average phonon frequency ω ln , the electron-phonon coupling parameter λ ep and the screened and retarded Coulomb repulsion parameter µ*: Clearly, low atomic masses lead to high frequency phonon modes, which may enhance the ω ln prefactor and thus T C . This is the basis of the so-called isotope effect. Furthermore, strong covalent bonding will lead both to large phonon frequencies and a large electron-phonon coupling potential V ep =λ ep /N(E F ), with N(E F ) the density of states at the Fermi level, also contributing to enhance T C . Even within a phonon-mediated coupling scenario, these criteria do not necessarily warrant a large T C since increasing λ ep may also lead to a lattice instability, and a large electron-phonon potential V ep may be impaired by a low density N(E F ). However, these simple considerations, as well as more elaborate surveys and predictions of a larger T C [14][15][16] , have provided much incentive to study this class of materials.The most familiar covalent systems are certainly diamond and silicon. The former can be considered as the prototype insula...

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“…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 superconductivity. SrTiO 3−x , the most dilute semiconductor known to date, has T c 0.5 K and its superconductivity can not be explained by simple electron-phonon coupling [18,19].…”

mentioning

confidence: 99%

“…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 superconductivity. SrTiO 3−x , the most dilute semiconductor known to date, has T c 0.5 K and its superconductivity can not be explained by simple electron-phonon coupling [18,19].…”

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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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Superconductivity in Germanium Telluride

Cited by 154 publications

References 1 publication

Superconductivity in carrier-doped silicon carbide

Superconductivity in carrier-doped silicon carbide

Superconducting group-IV semiconductors

Unconventional Superconductivity in YPtBi and Related Topological Semimetals

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