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 language | English |
---|---|
Pages (from-to) | 809-815 |
Number of pages | 7 |
Journal | Pramana - Journal of Physics |
Volume | 58 |
Issue number | 5-6 |
DOIs | |
Publication status | Published - 1 Jan 2002 |
MoE publication type | A4 Article in a conference publication |
Event | International Symposium on Advances in Superconductivity and Magnetism - Mangalagangothri, India Duration: 25 Sep 2001 → 28 Sep 2001 |
Keywords
- Magnetic superconductor
- Microstructure
- Rutheno cuprates
- Structural analysis