Development of Point-Contact Spectroscopy of Heavy-Fermion Superconductors under Pressure

Sakai, Y; Motoyama, Gaku; Yamaguchi, Akira; Sumiyama, Akihiko; Yamamura, Akihiro; Sato, Isamu

doi:10.1143/jpsjs.81sb.sb068

Cited by 6 publications

(3 citation statements)

References 12 publications

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“…This method has been successfully implemented for the study of the superconducting order parameter of various superconductors at ambient pressure (see the review Ref. 38 and references within), as well as the hidden order and antiferromagnetic phases of URu 2 Si 2 at high pressure, 58,59 with the advantage of reliable stability over a large temperature range.…”

Section: Soft Pcs Measurementsmentioning

confidence: 99%

“…In recent years it has been demonstrated that the soft point-contact spectroscopy can be adapted to a highpressure environment. 58,59 Instead of the conventional PCS method with a sharp metal tip, SPCS contacts used here are made by dipping the end of a 25 µm-diameter platinum wire into Ag epoxy and attaching it to the [001] surface of the crystal. This method has been successfully implemented for the study of the superconducting order parameter of various superconductors at ambient pressure (see the review Ref.…”

Section: Soft Pcs Measurementsmentioning

confidence: 99%

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Two-channel point-contact tunneling theory of superconductors

et al. 2014

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We introduce a two-channel tunneling model to generalize the widely used BTK theory of pointcontact conductance between a normal metal contact and superconductor. Tunneling of electrons can occur via localized surface states or directly, resulting in a Fano resonance in the differential conductance G = dI/dV . We present an analysis of G within the two-channel model when applied to soft point-contacts between normal metallic silver particles and prototypical heavy-fermion superconductors CeCoIn5 and CeRhIn5 at high pressures. In the normal state the Fano line shape of the measured G is well described by a model with two tunneling channels and a large temperatureindependent background conductance. In the superconducting state a strongly suppressed Andreev reflection signal is explained by the presence of the background conductance. We report Andreev signal in CeCoIn5 consistent with standard d x 2 −y 2 -wave pairing, assuming an equal mixture of tunneling into [100] and [110] crystallographic interfaces. Whereas in CeRhIn5 at 1.8 and 2.0 GPa the signal is described by a d x 2 −y 2 -wave gap with reduced nodal region, i.e., increased slope of the gap opening on the Fermi surface. A possibility is that the shape of the high-pressure Andreev signal is affected by the proximity of a line of quantum critical points that extends from 1.75 to 2.3 GPa, which is not accounted for in our description of the heavy-fermion superconductor.

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Section: Soft Pcs Measurementsmentioning

confidence: 99%

Section: Soft Pcs Measurementsmentioning

confidence: 99%

Two-channel point-contact tunneling theory of superconductors

et al. 2014

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“…We have developed a new method of making a PC to be able to measure PC spectrum under pressure and high magnetic field [19]. In our method of making a PC, an epoxide-based adhesive was used as an insulation material, and a silver layer was deposited by a vacuum evaporation equipment to serve as a counter electrode.…”

Section: Experimental Methodsmentioning

confidence: 99%

Point-Contact Spectroscopy of Heavy Fermion Compound CeRu₂Si₂ in Magnetic Field

Motoyama

Tachikake

Yamaguchi

et al. 2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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We have developed a new method to measure point-contact spectroscopy under pressure and in magnetic field, in which a thin-film deposition technique is used for making a point contact. In this work, we investigated a field dependence of the point-contact spectra of the heavy fermion compound CeRu 2 Si 2 single crystal, data is obtained in the form of differential resistivity dV /dI as a function of bias voltage V and the magnetic field applied along the a and c-axis. A zero bias peak on the dV /dI developed below 10 K in zero magnetic field. We consider that the peak structure is concerned with the Kondo effect. At high magnetic field of 13 T, the zero bias peak persisted although it was slightly suppressed.

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