UNSPECIFIED (1997) Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y). LOW TEMPERATURE PHYSICS, 23 (9). pp. 712-723. ISSN 1063-777X

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Abstract

The point-contact (PC) d(2)V/dI(2)-spectra of HoNi2B2C and YNI2B2C reveal structure at applied voltages corresponding to the phonon frequencies. At about 4 meV a maximum is observed in the phonon density 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 YNI2B2C [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 lambda-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. (C) 1997 American Institute of Physics.

Item Type:	Journal Article
Subjects:	Q Science > QC Physics
Journal or Publication Title:	LOW TEMPERATURE PHYSICS
Publisher:	AMER INST PHYSICS
ISSN:	1063-777X
Date:	September 1997
Volume:	23
Number:	9
Number of Pages:	12
Page Range:	pp. 712-723
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/16361

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