Point-contact spectroscopy of the electron-phonon interaction in single-crystal LaB6

Abstract

Point-contact spectra of single-crystal LaB6 are obtained, yielding the energy positions of all the phonon modes up to 160 me V. A relatively strong anisotropy of the spectra is observed. It is related to the anisotropy of the phonon system. The point-contact electron-phonon interaction function and the point-contact electron-phonon interaction parameter are compared with published calculated data and a qualitative agreement is found. From the measured spectra the temperature dependence of the LaB6 electrical resistivity and heat capacity are calculated.

Defect Mode in LaB_{6}

“…In our opinion, C res /T 3 describes the defect mode term induced by the presence of boron vacancies in the RB 6 matrix. Indeed as it was predicted in [6] and then proved by the results of point contact spectroscopy [8], XRD and neutron diraction investigations (see for example [9]), there are about 1-9% of vacancies in the boron sublattice in RB 6 . The presence of boron vacancies in combination with loosely bonded states of RE ions leads to a displacement of some of R 3+ ions from their central positions inside the B 24 cells in RB 6 .…”

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB6

“…Spectra with the best resolution have been obtained on the shiny blue YB 6 surfaces prepared by cleaving before cooling down in the cryostat. PC spectroscopy measurements (the first and second derivatives of I −V characteristics) have been realized by the standard lock-in modulation technique [8].…”

Point-Contact Spectroscopy of Crystalline Electric Field of Heterocontacts PrB6and NdB6with Pt

“…In magnetically ordered phase we have seen another 2 maxima at ≈ 22 and ≈ 31 mV which are less pronounced in the paramagnetic state (due to thermal smearing of PC spectra). Taking into account the phonon point-contact spectra of LaB 6 [9] we conclude that this structure is due to the interaction of conduction electrons with phonons in NdB 6 .…”

“…In the incommensurate (IC) phase it lies at 5.4 mV. This peak cannot be connected with CEF structure neither with phonon structure determined by PC spectroscopy in isomorphous LaB 6 compounds, because the lowest phonon peak is at about 12 mV [9]. Therefore, taking into account the molecular weight correction, the peak at 10.5 mV (not shifted with changing temperature) is connected with phonons of PrB 6 .…”