Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C(R=Ho, Y)

Электpонные свойства металлов и сплавов

Автор(и)

  • A. G. M. Jansen Grenoble High Magnetic Field Laboratory, Max-Planck-Institut fur Festkorperforschung and Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, France
  • P. Wyder Grenoble High Magnetic Field Laboratory, Max-Planck-Institut fur Festkorperforschung and Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, France
  • I. K. Yanson B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 310164 Kharkov, Ukraine
  • V. V. Fisun B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 310164 Kharkov, Ukraine
  • P. C. Canfield Ames Laboratory, Iowa State University, Ames, IA 50011, USA
  • B. K. Cho Ames Laboratory, Iowa State University, Ames, IA 50011, USA
  • C. V. Tomy Department of Physics, University of Warwick, Coventry CV4 7AL, UK
  • D. McK. Paul Department of Physics, University of Warwick, Coventry CV4 7AL, UK

Ключові слова:

PACS: 74.70.Ad, 74.25.Kc, 73.40.Jn, 72.10.Di

Анотація

The point-contact (PC) d2V/dI2-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 &quotquasi-thermal&quot behavior, the detailed magnetic-field and temperature dependences of the 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 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.

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Опубліковано

1997-09-10

Як цитувати

(1)
Jansen, I. K.; Wyder, V. V.; Yanson, A. G. M.; Fisun, P.; Canfield, P. C.; Cho, B. K.; Tomy, C. V.; Paul, D. M. Point-Contact-Spectroscopy Evidence of Quasi-Particle Interactions in RNi2B2C(R=Ho, Y): Электpонные свойства металлов и сплавов. Fiz. Nizk. Temp. 1997, 23, 951-964.

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