Andreev bound state and multiple energy gaps in the noncentrosymmetric superconductor BiPd

Mondal, Mintu; Joshi, Bhanu; Kumar, Sanjeev; Kamlapure, Anand; Ganguli, Somesh Chandra; Thamizhavel, A.; Mandal, Sudhansu S.; Ramakrishnan, S.; Raychaudhuri, Pratap

doi:10.1103/physrevb.86.094520

Cited by 72 publications

(92 citation statements)

References 41 publications

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“…It is worth pointing out that the fitted parameters for a given temperature may be correlated and therefore not unique, especially if one assumes a temperature dependence of the weight p. A similar assumption, for instance, has been used in Ref. [33] for describing the charge conductance of the noncentrosymmetric superconductor BiPd. Here, since a physical justification of such a temperature dependence is not directly linkable to the adopted model, we have performed the fit in a way to optimally reproduce the whole set of data across the full range of temperatures by keeping the amplitude of p unchanged.…”

Section: A Point Contact Spectroscopymentioning

confidence: 99%

“…We assume that the two bands contribute through parallel channels to the charge conductance with a probability p that is also employed in the fit to tune the weight of each band in the transport. This model has been also applied to successfully describe the conductance spectra of the noncentrosymmetric superconductor BiPd [33].…”

Section: A Point Contact Spectroscopymentioning

confidence: 99%

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Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

et al. 2015

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Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. We combine point contact spectroscopy with specific heat measurements to probe the superconducting state in noncentrosymmetric Nb 0.18 Re 0.82 single crystals. The conductance spectra clearly exhibit a two-peak structure that is well reproduced within a two-band model with isotropic gaps in the spectrum. Such an observation is confirmed by distinct features of the specific heat both at low temperatures and in the range approaching the transition to the normal state. The analyses provide convincing evidence that the two-gap superconducting pairing is a robust feature of Nb 0.18 Re 0.82 .

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Section: A Point Contact Spectroscopymentioning

confidence: 99%

Section: A Point Contact Spectroscopymentioning

confidence: 99%

Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

et al. 2015

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“…More recently, two members of the Bi-Pd family of superconductors have been found to exhibit topologically protected surface states with Rashba-like spin splitting. While the superconducting state of noncentrosymmetric BiPd appears to be topologically trivial [43][44][45], the pairing symmetry of centrosymmetric β-Bi 2 Pd remains to be elucidated [46][47][48][49][50][51][52]. Despite the fact that spin-and angleresolved photoemission spectroscopy (ARPES) has revealed the presence of notrivial surfaces states at the Fermi level [46], no Andreev bound states associated with Majorana fermions have been observed in pointcontact spectroscopy [48].…”

Section: Introductionmentioning

confidence: 99%

Evolution of the topologically protected surface states in superconductorβ-Bi₂Pd from the three-dimensional to the two-dimensional limit

Wang

Margine

2017

J. Phys.: Condens. Matter

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The recent discovery of topologically protected surface states in the noncentrosymmetric α-BiPd and the centrosymmetric β-Bi2Pd has renewed the interest in the Bi-Pd family of superconductors. Here, we employ first-principles calculations to investigate the structure, electronic, and topological features of β-Bi2Pd, in bulk and in thin films of various thicknesses. We find that the Van der Waals dispersion corrections are important for reproducing the experimental structural parameters, while the spin-orbit interaction is critical for properly describing the appearance of topological electronic states. By increasing the thickness of the slab, the Dirac-cone surface states and the Rashba-type surface states gradually emerge at 9 and 11 triple-layers.

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“…α-BiPd is recently synthesized with all the aforementioned properties obtained intrinsically, and thus provides the long-sought material for new experiments and applications. So far, there have been few works on this material, mainly studying the magnetic and transport phenomena [9][10][11]. Again, for the spectroscopic investigations, there is only one ARPES [12] and one scanning tunnelling spectroscopy (STS) study [13].…”

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Unusual Dirac Fermions on the Surface of a Noncentrosymmetric α -BiPd Superconductor

et al. 2016

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Combining multiple emergent correlated properties such as superconductivity and magnetism within the topological matrix can have exceptional consequences in garnering new and exotic physics. Here, we study the topological surface states from a noncentrosymmetric α-BiPd superconductor by employing angle-resolved photoemission spectroscopy (ARPES) and first principle calculations. We observe that the Dirac surface states of this system have several interesting and unusual properties, compared to other topological surface states. The surface state is strongly anisotropic and the inplane Fermi velocity varies rigorously on rotating the crystal about the y-axis. Moreover, it acquires an unusual band gap as a function of ky, possibly due to hybridization with bulk bands, detected upon varying the excitation energy. Coexistence of all the functional properties, in addition to the unusual surface state characteristics make this an interesting material. α-BiPd is recently synthesized with all the aforementioned properties obtained intrinsically, and thus provides the long-sought material for new experiments and applications. So far, there have been few works on this material, mainly studying the magnetic and transport phenomena [9][10][11]. Again, for the spectroscopic investigations, there is only one ARPES [12] and one scanning tunnelling spectroscopy (STS) study [13]. The ARPES work reported the electronic structure of this compound with the detection of topological Dirac cone at -0.7 eV below the Fermi level (E F ), without detailing the properties of Dirac cone, while the STS work reported the states above the Fermi level.In this paper we report several interesting and unusual properties of the topological Dirac states present on the surface of this noncentrosymmetric α-BiPd superconductor by employing ARPES and first principle calculations. We detect the surface states that are having a Dirac node at a binding energy of 0.7 eV below Fermi level (E F ) at the Γ point dispersing along the Γ − X high symmetry line. Upon varying the photon energy, we notice surface states that are gapped as a function of k y at the node due to a possible hybridization with bulk bands, a unique feature of the surface state that is not disclosed in this compound so far. Upon varying the photon polarization we identify the orbital character of the detected bands.We further show that the Dirac fermions in α-BiPd are highly anisotropic on rotating the crystal about the y-axis such that, in going from Γ−X to Γ−Z the massless linear dispersive Dirac states become flat dispersive massive fermions. Therefore, the Dirac states found in this compound are of one dimensional (1D) character which could provide a natural route for the quantum wires. In general, the Dirac states found on the surface of 2D compounds such as graphene [14] [24]. Unusual band structure of this material, surface state is gapped and asymmetric, make this a unique compound which will attract tremendous future research interests.Single crystals of stoichiometric α-BiPd were g...

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Andreev bound state and multiple energy gaps in the noncentrosymmetric superconductor BiPd

Cited by 72 publications

References 41 publications

Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

Evolution of the topologically protected surface states in superconductorβ-Bi₂Pd from the three-dimensional to the two-dimensional limit

Unusual Dirac Fermions on the Surface of a Noncentrosymmetric α -BiPd Superconductor

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Andreev bound state and multiple energy gaps in the noncentrosymmetric superconductor BiPd

Cited by 72 publications

References 41 publications

Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

Evidence of double-gap superconductivity in noncentrosymmetricNb0.18Re0.82single crystals

Evolution of the topologically protected surface states in superconductorβ-Bi2Pd from the three-dimensional to the two-dimensional limit

Unusual Dirac Fermions on the Surface of a Noncentrosymmetric α -BiPd Superconductor

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Evolution of the topologically protected surface states in superconductorβ-Bi₂Pd from the three-dimensional to the two-dimensional limit