Point-contact spectroscopy of the antiferromagnetic superconductor HoNi2B2C

✍ Scribed by Yu.G. Naidyuk; O.E. Kvitnitskaya; I.K. Yanson; G. Fuchs; K. Nenkov; A. Wälte; G. Behr; D. Souptel; S.-L. Drechsler

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 399 KB
• Volume: 460-462
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.03.165

✦ Synopsis

The point-contact (PC) spectroscopy study of the electron-phonon (boson) interaction (EP(B)I) spectral function in HoNi 2 B 2 C reveals phonon maxima at 16 and 22 meV and 34 meV. For the first time the pronounced high energy maxima at about 50 meV and 100 meV were resolved. Additionally, an admixture of a crystalline-electric-field (CEF) excitation with a maximum near 10 meV and a 'magnetic' peak near 3 meV are observed. The contribution of the CEF peak in EP(B)I constant k PC is evaluated as 20-30%, while contribution of the high frequency modes at 50 and 100 meV amounts about 10% for each maxima. PC Andreev reflection measurements below the critical temperature T c ' 8.5 K reveals two different superconducting (SC) states separated by T Ã c ' 5:6 K which is close to the Ne ´el temperature T N ' 5.3 K. Below T Ã c the gap D in HoNi 2 B 2 C exhibits a standard single-band BCS-like behavior with 2D=k B T Ã c ' 3:9. Above T Ã c the gap features in PC spectra are strongly suppressed pointing to a peculiar SC state between T Ã c and T c , where incommensurate magnetic order develops.