Comment on magnetism and superconductivity in rutheno cuprates: RuSr2GdCu2O8 and RuSr2Gd1.5Ce0.5Cu2O10

V. P.S. Awana*, M. Karppinen, H. Yamauchi

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

3 Citations (Scopus)

Abstract

Both RuSr2GdCu2O8-δ (Ru-1212) and RuSr2Gd1.5Ce0.5Cu2O 10-δ (Ru-1222) exhibits magnetism and superconductivity, as seen by magnetization vs. temperature behavior measured in 5 Oe field. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization data show branching at around 140 K and 100 K with a cusp at 135 K and 80 K and a diamagnetic transition around 20 K and 30 K in the ZFC part, for Ru-1212 and Ru-1222, respectively. The isothermal magnetization possesses a non-linear contribution due to a ferromagnetic component at low temperatures below 50 K for both samples. The resistance vs. temperature behavior of the samples in applied fields of 0, 3 and 7 T confirmed superconductivity, with a different type of broadening of the superconductivity transition under magnetic fields for Ru-1212 from that known for conventional high-Tc superconductors. The magnetoresistance (MR) is negative above the Ru magnetic ordering temperature at 135 K. Below the Ru magnetic ordering temperature, MR displays a positive peak at low fields and becomes negative at higher fields for Ru-1212. For Ru-1222, MR remains negative both above and below the ordering temperature. A maximum of 2% is observed for the negative MR value at the Ru magnetic ordering temperature. An electron diffraction pattern obtained for the Ru-1212 sample shows two types of superstructure: one has a weak spot at the centre of the a-b rectangle, and the other only along the b direction. Interestingly, Ru-1222 shows only clean a-b and a-c planes, without any superstructures.

Original languageEnglish
Pages (from-to)809-815
Number of pages7
JournalPramana - Journal of Physics
Volume58
Issue number5-6
DOIs
Publication statusPublished - 1 Jan 2002
MoE publication typeA4 Article in a conference publication
EventInternational Symposium on Advances in Superconductivity and Magnetism - Mangalagangothri, India
Duration: 25 Sep 200128 Sep 2001

Keywords

  • Magnetic superconductor
  • Microstructure
  • Rutheno cuprates
  • Structural analysis

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