Point-contact spectroscopy in the Centre of Low Temperature Physics Košice (Review article)

Point-contact spectroscopy offers a unique straightforward possibility to study the electronic properties of metals. Soon after the invention of this technique by Igor Yanson in the B. Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine [Sov. Phys. JETP39, 506 (1974)], multiple laboratories adopted this technique and applied it to various topical problems in modern solid-state physics. Here, we offer a brief review of how point-contact spectroscopy has been developed and used in the Centre of Low Temperature Physics Košice. By this technique, we were able to obtain for example the spectrum of the electron-phonon interaction in an unprecedented large energy scale up to 160 meV in LaB6. The Zeeman splitting of the Pr3+ ion levels in the crystal-electric field has been detected for the first time in PrNi5. “Inverse” point-contact spectra of the electron-phonon interaction found in semimetallic arsenic were explained by the weak localization in the point-contact area. The point-contact Andreev reflection spectroscopy enabled to detect not only the superconducting energy gap in YB6, but also the Einstein-like phonon mode responsible for superconductivity. The first spectroscopic evidence of the two-gap superconductivity in MgB2 has been provided in our experiments. High spin polarization in Co2FeSn Heusler nanowires for spintronics has been obtained.