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Investigation of magnetic characteristics of oxygen adsorbed YbFe2As2 single crystals

Recent discovery of superconductivity in iron pnictides had attracted immense attention of the scientific community. The parent compounds were spin density wave (SDW) metals unlike the high-TC superconductors which were Mott insulators. In this present study, we synthesized single crystal of a new compound YbFe2As2 by using high temperature solution growth technique without flux. The YbFe2As2 single crystals had been systematically characterized by energy dispersive X-ray analysis (EDAX). The presence of oxygen was found by EDAX on the surfaces of grown YbFe2As2 single crystals which had been kept in air ambience for few months. The measurement of magnetization (M) versus temperature (T) using SQUID at constant magnetic field (H = 100 Oe) for YbFe2As2 had revealed an occurrence of sharp slope change around 140 K which was the known SDW transition temperature for the parent compound BaFe2As2. An additional slope change had been observed around 40 K. M vs T data at H= 10000 Oe had exhibited paramagnetic behavior. Result of M versus H measurements for YbFe2As2 at 2 K had shown that the saturation had not been achieved at H = 80000 Oe. We had carried out magnetization measurements for oxygen adsorbed YbFe2As2 (YbFe2As2 : O2 ) and BaFe2As2 (BaFe2As2 : O2) for comparative study also.