Nmr evidence for coexistence of superconductivity and ferromagnetic component in magnetic superconductor RuSr2YCu2O8: 99,101Ru and 63Cu NMR

Y Tokunaga; H Kotegawa; K Ishida; Y Kitaoka; H Takagiwa; J Akimitsu

doi:10.1103/PhysRevLett.86.5767

Nmr evidence for coexistence of superconductivity and ferromagnetic component in magnetic superconductor RuSr2YCu2O8: 99,101Ru and 63Cu NMR

Phys Rev Lett. 2001 Jun 18;86(25):5767-70. doi: 10.1103/PhysRevLett.86.5767.

Authors

Y Tokunaga¹, H Kotegawa, K Ishida, Y Kitaoka, H Takagiwa, J Akimitsu

Affiliation

¹ Department of Physical Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan. tokunaga@nmr.mp.es.osaka-u.ac.jp

PMID: 11415353
DOI: 10.1103/PhysRevLett.86.5767

Abstract

From Ru- and Cu-NMR studies, we present evidence for coexistence of superconductivity and ferromagnetism in a cuprate superconductor RuSr2YCu2O8 (RuY1212). The observation of a large enhancement of a radio-frequency field for the Ru-NMR signal at zero field reveals the existence of a ferromagnetic (FM) component in the ordered RuO2 plane below a Curie temperature of TM = 150 K. Just below the onset temperature of superconductivity T(onset)c = 45 K, a remarkable decrease of the nuclear spin-lattice relaxation rate 1/T1 was observed within the ordered RuO2 plane as well as the CuO2 plane, revealing that the superconducting gap coexists with the FM component in the RuO2 plane on a microscopic scale. In addition, from the observation of a sharp peak in 101(1/T1) at T(zero)c approximately 23 K where the resistivity becomes zero, we suggest that the motion of self-induced vortices originating from fluctuations of the FM component induces the resistivity between T(onset)c and T(zero)c in RuY1212.