Critical fields and the spontaneous vortex state in the weakly ferromagnetic superconductor RuSr2GdCu2O8

C. Y. Yang, B. C. Chang, H. C. Ku, Y. Y. Hsu

Research output: Contribution to journalArticle

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Abstract

A spontaneous vortex state (SVS) between 30 and 56 K was observed for the weak-ferromagnetic superconductor RuSr2GdCu2O8 with the ferromagnetic Curie temperature TC=131K and the superconducting transition temperature Tc=56K. The low-field (±20G) super-conducting hysteresis loop indicates a narrow Meissner state region within the average lower critical field Bc1(T)=Bc1(0)[1-(TT0)2], with average Bc1ave(0)=12G and T0=30K. Full Meissner shielding signal in very low applied field indicates an ab plane Bc1ab(0)∼4G with an estimated anisotropic parameter γ∼7 for this layered system. The existence of a spontaneous vortex state between 30 and 56 K is the result of weak-ferromagnetic order with a net spontaneous magnetic moment of ∼0.1μBRu, which generates a weak magnetic dipole field around 10 G in the CuO2 bilayers. The upper critical field Bc2 varies linearly as (1-TTc) up to 7-T field. The vortex melting line Bm varies as (1-TTm)3.5 with melting transition temperature Tm=39K and a very broad vortex liquid region due to the coexistence and the interplay between superconductivity and weak-ferromagnetic order.

Original languageEnglish
Article number174508
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume72
Issue number17
DOIs
Publication statusPublished - 2005 Nov 1

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Superconducting materials
Vortex flow
vortices
Superconducting transition temperature
transition temperature
melting
Curie temperature
Hysteresis loops
Superconductivity
Magnetic moments
magnetic dipoles
Shielding
shielding
Melting point
Melting
superconductivity
magnetic moments
hysteresis
conduction
Liquids

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Critical fields and the spontaneous vortex state in the weakly ferromagnetic superconductor RuSr2GdCu2O8. / Yang, C. Y.; Chang, B. C.; Ku, H. C.; Hsu, Y. Y.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 72, No. 17, 174508, 01.11.2005.

Research output: Contribution to journalArticle

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