Competition of multiband superconducting and magnetic order in ErNi2B2C observed by Andreev reflection

• Published in: Europhysics letters Vol. 83; no. 3; pp. 37003 - 37003(5)
• Main Authors: Bobrov, N. L, Chernobay, V. N, Naidyuk, Yu. G, Tyutrina, L. V, Naugle, D. G, Rathnayaka, K. D. D, Bud'ko, S. L, Canfield, P. C, Yanson, I. K
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2008; EDP Sciences
• Subjects: 74.45.+c; 74.50.+r; 74.70.Dd
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/83/37003

Point contacts (PC) Andreev reflection dV/dI spectra for the antiferromagnetic ($T_{\rm N}\simeq$ 6 K) superconductor ($T_{\rm c}\simeq$ 11 K) ErNi2B2C have been measured for the two main crystallographic directions. The observed retention of the Andreev reflection minima in dV/dI up to Tc directly points to an unusual superconducting order parameter (OP) vanishing at Tc. The temperature dependence of the OP was obtained from dV/dI using the recent theory of Andreev reflection including the pair-breaking effect. For the first time the existence of two superconducting OPs in ErNi2B2C is shown. A distinct decrease of both OPs as temperature is lowered below TN is observed.