Document Type

Article

Publication Date

9-1997

Journal or Book Title

Low Temperature Physics

Volume

23

Issue

9

First Page

712

Last Page

723

DOI

10.1063/1.593378

Abstract

The point-contact (PC) d2V/dI2-spectra of HoNi2B2C and YNl2B2C reveal structure at applied voltages corresponding to the phonon frequencies. At about 4 meV a maximum is observed in the phonondensity of states by analogy to the soft-phonon structure in neutron scattering experiments for LuNi2B2C [P. Dervenagas et al., Phys. Rev. B52, R9839 (1995)]and YNl2B2C [H. Kawano et al., Czech. J. Phys. 46, S2-825 (1996), Phys. Rev. Lett.77, 4628 (1996)]. In the Ho compound the low-energy phonon peak is suppressed by an applied magnetic field in an anisotropic way, pointing to an interaction between the phonons and the magnetic systems. Surprisingly, in the nonmagnetic Y compound the 4-meV peak is also suppressed by a magnetic field. In the Ho-compound contacts which show the 〈quasi-thermal〉 behavior, the detailed magnetic-field and temperature dependences of PC spectra suggest that the magnetic order is destroyed due to the coupled phonon-magnon subsystem which is driven out of equilibrium by electrons that pass through the contact, by analogy with the nonequilibrium phonon-induced destruction of the superconducting state in point contacts [I. K. Yanson et al., JETP Lett. 45, 543 (1987)]. The PC electron-phonon interaction(EPI) spectral functions are reconstructed and the estimates for the λ-parameter yield the values of the order of 0.1. Comparison with PC EPI spectra of nonsuperconducting and nonmagnetic LaNi2B2C. [I. K. Yanson et al., Phys. Rev. Lett. 78, 935 (1997)], as well as the comparative study of PC EPI and Andreev-reflection spectra for various contacts with superconducting Ho and Y compounds suggest that the low-energy part of the electron-quasi-particle interaction spectral function is responsible for the Cooper pairing in these materials.

Comments

The following article appeared in Low Temperature Physics 23 (1997): 712 and may be found at http://dx.doi.org/10.1063/1.593378.

Rights

Copyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

Copyright Owner

American Institute of Physics

Language

en

File Format

application/pdf

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