Superconductivity in Bi observed with point contacts

Shklyarevskiǐ, O. I.; Duif, A.M.; Jansen, A. G. M.; Wyder, P.

doi:10.1103/physrevb.34.1956

Cited by 17 publications

(13 citation statements)

References 7 publications

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“…The reason of their appearance may be associated with the fast decrease of the Andreev-reflection current near eV = ∆ and chargeimbalance processes. Besides, the superconducting clusters situated at the contact area periphery may result such the horns [11]. In some measurements the spectra occur not symmetrical, as it is shown in Figs.…”

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confidence: 91%

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe4Al8

Dmitriev

Rybaltchenko

Wyder

et al. 2002

Low Temperature Physics

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For the first time we present the direct evidence for superconductivity in the ternary magnetic compound YFe 4 Al 8 with the ThMn 12 type structure found via point-contact (PC) experiments on contacts between silver needle and single-crystal YFe 4 Al 8 , revealing the distinct Andreev-reflection current. The spectra measured prove the existence of normal-superconducting interface and exhibit the triangular-like shape in a vicinity of zero-bias voltage, inferring the unconventional type of superconductivity. The derived dependences of the order parameter versus temperature ∆(T) and magnetic field ∆(H) are presented. ∆(T) follows BCS theory, whereas ∆(H) do not satisfy any theoretical predictions. In some cases there exists noticeable superconductivity enhancement by a weak magnetic field. The data obtained imply the very inhomogeneous distribution of superconductivity over the sample volume in spite of its single crystal structure. We assume that the reason is associated with inherent magnetic inhomogeneities of this material. The highest values for the critical temperature T c , upper critical magnetic field H c2 , and ratio 2∆(0)/kT c are 7.4 K, 5 T, and 7.2, respectively. [3]. In this work we give, for the first time, the direct evidence for the existence of superconductivity in the rare-earth ternary magnetic compound YFe 4 Al 8 in an Andreevreflection experiment.The family of ternary magnetic compounds ReM 4 Al 8 (Re is a rare earth, M is a transition metal) with the ThMn 12 type structure is known for about two decade and their physical properties have been investigated extensively [4][5][6]. However, weak signs of superconductivity in some of the compounds belonging to this family were discovered only recently in the radio-frequency impedance and heat capacity experiments [7,8]. This is very surprising, because the compounds of this type have a

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confidence: 91%

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe4Al8

Dmitriev

Rybaltchenko

Wyder

et al. 2002

Low Temperature Physics

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“…2(c)]. The deviations are either due to the strong coupling effects in lead or the high current densities achieved in our samples (10 9 A͞cm 2 at 10 mV for a 10 V sample) which can lead to partial gap suppression [18]. Figure 3(a) shows the point-contact spectra ͑dR͞dV vs V ͒ for the same Pb-Cu sample both in the normal and the superconducting state.…”

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confidence: 95%

Probing Ferromagnets with Andreev Reflection

et al. 1998

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High transmissivity, ferromagnet-superconductor thin film nanocontacts are studied experimentally. Compared to nonmagnetic metal-superconductor contacts, Andreev reflection is strongly suppressed due to the spin polarization of conduction electrons in the ferromagnet. This effect is used to measure both the transparency of the interface and spin polarization of the direct current in the ferromagnet in contrast to the spin polarization of the tunneling current previously measured in ferromagnet-insulatorsuperconductor systems. [S0031-9007(98)07318-9]

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“…Alternatively, interface superconductivity between a normal material and a TI has also been discovered [20][21][22]. It has been reported that the point contact between a normal metal and Bi, Sb, or Bi 1−x Sb x alloy shows unusual properties that are ascribed to the presence of superconducting clusters [20].…”

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confidence: 99%

“…It has been reported that the point contact between a normal metal and Bi, Sb, or Bi 1−x Sb x alloy shows unusual properties that are ascribed to the presence of superconducting clusters [20]. This phenomenon was explained as a result of the difference in the contact potential, which generates an electric dipole layer at the junction and turns the semimetal, Bi and Sb, or semiconductor Bi 1−x Sb x into a superconductor [20,21]. However, the role played by the spin-polarized surface states that were recently discovered in Bi 1−x Sb x [23,24] for inducing the observed superconductivity has not been studied.…”

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Onset of a Two-Dimensional Superconducting Phase in a Topological-Insulator–Normal-Metal Bi1−xSbx/Pt Junction Fabricated

Teslich

Dai

et al. 2018

Phys. Rev. Lett.

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Inducing superconductivity in a topological insulator can lead to novel quantum effects. However, experimental approaches to turn a topological insulator into a superconductor are limited. Here, we report on superconductivity in topological insulator Bi_{0.91}Sb_{0.09} induced via focused ion-beam deposition of a Pt thin film. The superconducting phase exhibits a Berezinski-Kosterlitz-Thouless transition, demonstrative of its two-dimensional character. From the in-plane upper critical field measurements, we estimate the superconducting thickness to be ∼17 nm for a 5.5-μm-thick sample. Our results provide evidence that the interface superconductivity could originate from the surface states of Bi_{0.91}Sb_{0.09}.

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Superconductivity in Bi observed with point contacts

Cited by 17 publications

References 7 publications

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe4Al8

Direct evidence for the occurrence of superconductivity in the magnetic compound YFe4Al8

Probing Ferromagnets with Andreev Reflection

Onset of a Two-Dimensional Superconducting Phase in a Topological-Insulator–Normal-Metal Bi1−xSbx/Pt Junction Fabricated

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