Superconductivity in noncentrosymmetric BiPd

Joshi, Bhanu; Thamizhavel, A.; Ramakrishnan, S.

doi:10.1103/physrevb.84.064518

Cited by 85 publications

(124 citation statements)

References 29 publications

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“…CePt 3 Si [1] has attracted great attention of condensed matter physics community. Similarly, some other noncentrosymmetric superconductors have been studied in recent past with conventional superconducting behavior such as Ru 7 B 3 , Mg 10 Ir 19 B 16 , α-BiPd, and the cubic phases of Re 3 W, and Re 24 Nb 5 [2][3][4][5][6][7]. Further, superconductivity has been reported in ntype metallic interface being formed between the LaAlO 3 and SrTiO 3 interface, which is naturally an inversion symmetry system without up-down reflection [8].…”

Section: Introductionmentioning

confidence: 99%

Weak ferromagnetism in a noncentrosymmetric BiPd 4 K superconductor

Jha

Goyal

Neha

et al. 2015

Supercond. Sci. Technol.

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We report synthesis of non-centrosymmetric BiPd single crystal by self flux method. The BiPd single crystal is crystallized in monoclinic structure with the P2 1 space group. Detailed SEM (Scanning Electron Microscopy) results show that the crystals are formed in slab like morphology with homogenous distribution of Bi and Pd. The magnetic susceptibility measurement confirmed that the BiPd compound is superconducting below 4K. Further, BiPd exhibits weak ferromagnetism near the superconducting transition temperature in isothermal magnetization (MH) measurements. The temperature dependent electrical resistivity also confirmed that the BiPd single crystal is superconducting at T c =4K. Magneto transport measurements showed that the estimated H c2 (0) value is around 7.0kOe. We also obtained a sharp peak in heat capacity Cp(T) measurements at below 4K due to superconducting ordering. The normalized specific-heat jump, C/γT c , is 1.52, suggesting the BiPd to be an intermediate BCS coupled superconductor. The pressure dependent electrical resistivity shows the T c decreases with increasing applied pressure and the obtained dT c /dP is -0.62K/Gpa.

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Section: Introductionmentioning

confidence: 99%

Weak ferromagnetism in a noncentrosymmetric BiPd 4 K superconductor

Jha

Goyal

Neha

et al. 2015

Supercond. Sci. Technol.

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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].…”

mentioning

confidence: 99%

“…Band structure calculations are performed on the orthorhombic crystal structure of α-BiPd [26], though the primitive unit cell is of monoclinic [9], using density functional theory within the generalized gradient approximation (GGA) of Perdew, Burke and Ernzerhof (PBE) exchange and correlation potential [27] as implemented in the Vienna ab-initio simulation package [28]. Projected augmented-wave (PAW) [29] pseudo-potentials are used to describe core electrons and spin-orbit coupling as included in the calculations.The electronic wavefunction is expanded using plane waves up to a cutoff energy of 500 eV.…”

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confidence: 99%

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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“…In NCS superconductors, Rashba-type antisymmetric spin-orbit coupling is allowed, 10 which is expected to lift the spin degeneracy and lead to a complex pairing wave function that might be characterized by a hybrid pairing of both spin-singlet and spin-triplet superconductivity. 9,11 According to a recent review article by Smidman et al 12 , a well-defined signature for distinguishing between the singlet and triplet component in the mixture should be the existence of topological states, which is exclusive to the pure spin-triplet pairing symmetry. However, it should be noted that experimental signature for spin-triplet superconductivity has also been observed in samples 13,14 that do not posses any topologically non-trivial states.…”

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confidence: 99%

Probing the superconducting gap symmetry of α−PdBi2 : A penetration depth study

et al. 2017

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We report measurements of the in-plane London penetration depth λ in single crystals of the α-PdBi2 superconductor -the α-phase counterpart of the putative topological superconductor β-PdBi2, down to 0.35 K using a high-resolution tunnel-diode-based technique. Both λ and superfluid density ρs exhibit an exponential behavior for T ≤ 0.35Tc, with ∆(0)/kBTc ∼2.0, ∆C/γTc∼2.0 and λ(0)∼140 nm, showing that α-PdBi2 is a moderately-coupling, fully-gapped superconductor. The values of ∆(0) and ∆C/γTc are consistent with each other via strong-coupling corrections.

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Superconductivity in noncentrosymmetric BiPd

Cited by 85 publications

References 29 publications

Weak ferromagnetism in a noncentrosymmetric BiPd 4 K superconductor

Weak ferromagnetism in a noncentrosymmetric BiPd 4 K superconductor

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

Probing the superconducting gap symmetry of α−PdBi2 : A penetration depth study

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