Magnetic and Thermal Behavior of Ru0.9Sr2YCu2.1O7.9 Magneto-Superconductor Synthesized by High-Pressure High-Temperature Technique

Abstract

The structural, physical, and thermal property details of Ru0.9Sr2YCu2.1O7.9 (Y/Ru-1212) superconducting material synthesized through high pressure (6 GPa) and a high temperature (1400 °C) (HPHT) route are reported here. (Y/Ru-1212) crystallizes in P4/mmm tetragonal structure and is found free of any detectable impurities through X-ray diffractometry. Ru-spins are ordered magnetically above 145 K, with a sizeable ferromagnetic component at 5 K. Further clear diamagnetic transitions are seen in both zero-field-cooled (ZFC) and field-cooled (FC) magnetic susceptibility measurements and exhibiting superconductivity below 50 K. Both the thermoelectric power (S) and thermal conductivity (κ) measurements show superconductivity onset below 50 K with S=0 at 30 K and a broad hump in heat capacity Cp(T) below 30 K. Heat capacity (Cp) measurements also exhibit the magnetic ordering temperature as a hump below 145 K. The appearance of a hump in Cp(T), instead of a clear transition, is indicative of short range magnetic correlations like spin glass (SG). Neither the high (145 K) nor the low (30 K) temperature humps of Cp(T) could be analyzed quantitatively because of short magnetic correlations in former and mixing of both superconductivity and FM components in a later case. The observed data is compared with various reported Ru-1212 systems synthesized under normal pressure conditions. It is concluded that HPHT synthesized Y/Ru-1212 is a bulk superconductor below 30 K with a substantial FM component.