Turkish Journal of Physics
DOI
-
Abstract
The isotope effect in the recently disvovered class o superconductors LuNi_2B_2C and La_3Ni_2B_2N_3 is investigated in the context of electron-squezed phonon interaction renormalizing the Ni-d electron-electron correlations. Squeezed phonon mode originates from the anharmonic character of the tetragonal Ni-B structure and is polarized in the vortical direction to the Ni layers. The isotope effect arises as a result of the zero point motion of the Ni-Ni d-electron hopping amplitude dominantly due to this vertical phonon mode. Within this model the isotope exponent is calculated to be \alpha_B \leq 0.20 as compared to the recently found experimental value \alpha_B^{exp} = 0.27 \mp 0.10. Finally, the phonon frequency softening predicted by our model eletron-phonon interaction is discussed within the context of recent experiments on the relevant boron A_{1g} softening.
First Page
863
Last Page
872
Recommended Citation
HAKİOĞLU, Tuğrul and IVANOV, Valery A. (1998) "Isotope Effect and Phonon Softening in Superconducting Borocarbides and Boronitrides," Turkish Journal of Physics: Vol. 22: No. 9, Article 2. Available at: https://journals.tubitak.gov.tr/physics/vol22/iss9/2
