TY - JOUR
T1 - Magneto-transport and magnetic susceptibility of SmFeAsO1-x Fx (x=0.0 and 0.20)
AU - Meena, R. S.
AU - Pal, Anand
AU - Kumar, Shiva
AU - Rao, K. V.R.
AU - Awana, V. P.S.
N1 - Funding Information:
Acknowledgements Authors would like to thank Director NPL Professor R.C. Budhani for his keen interest and encouragement for the study. Anand Pal and Shiva Kumar would like to thank CSIR-India for granting the senior research fellowship.
PY - 2013/7
Y1 - 2013/7
N2 - We report superconductivity in the SmFeAsO1-x Fx for the x=0.2 system being synthesized using the single step solid state reaction route. Rietveld analysis of room temperature X-ray diffraction (XRD) data shows the studied samples, SmFeAsO1-x Fx with x=0.0 and x=0.2, are crystallized in a single phase tetragonal structure with space group P4/nmm. The resistivity measurement shows superconductivity for the x=0.20 sample with Tc (onset) ∼51.7 K. The upper critical field, [Hc2(0)] is estimated ∼3770 kOe by Ginzburg-Landau (GL) theory. Broadening of superconducting transition in magnetotransport is studied through thermally activated flux flow in an applied field up to 130 kOe. The flux flow activation energy (U/kB ) is estimated ∼1215 K for 1 kOe field. Magnetic measurements exhibited bulk superconductivity with lower critical field (H c1) of ∼1.2 kOe at 2 K. In the normal state, the paramagnetic nature of compound confirms no trace of magnetic impurity, which orders ferromagnetically. AC susceptibility measurements have been carried out for SmFeAsO0.80F0.20 sample at various amplitude and frequencies of applied AC drive field. The intergranular critical current density (Jc ) is estimated. Specific heat [Cp (T)] measurement showed an anomaly at around 140 K due to the SDW ordering of Fe, followed by another peak at 5 K corresponding to the antiferromagnetic (AFM) ordering of Sm+3 ions in the SmFeAsO compound. Interestingly, the change in entropy (marked by the Cp transition height) at 5 K for Sm+3 AFM ordering is heavily reduced in the case of the superconducting SmFeAsO0.80F0.20 sample.
AB - We report superconductivity in the SmFeAsO1-x Fx for the x=0.2 system being synthesized using the single step solid state reaction route. Rietveld analysis of room temperature X-ray diffraction (XRD) data shows the studied samples, SmFeAsO1-x Fx with x=0.0 and x=0.2, are crystallized in a single phase tetragonal structure with space group P4/nmm. The resistivity measurement shows superconductivity for the x=0.20 sample with Tc (onset) ∼51.7 K. The upper critical field, [Hc2(0)] is estimated ∼3770 kOe by Ginzburg-Landau (GL) theory. Broadening of superconducting transition in magnetotransport is studied through thermally activated flux flow in an applied field up to 130 kOe. The flux flow activation energy (U/kB ) is estimated ∼1215 K for 1 kOe field. Magnetic measurements exhibited bulk superconductivity with lower critical field (H c1) of ∼1.2 kOe at 2 K. In the normal state, the paramagnetic nature of compound confirms no trace of magnetic impurity, which orders ferromagnetically. AC susceptibility measurements have been carried out for SmFeAsO0.80F0.20 sample at various amplitude and frequencies of applied AC drive field. The intergranular critical current density (Jc ) is estimated. Specific heat [Cp (T)] measurement showed an anomaly at around 140 K due to the SDW ordering of Fe, followed by another peak at 5 K corresponding to the antiferromagnetic (AFM) ordering of Sm+3 ions in the SmFeAsO compound. Interestingly, the change in entropy (marked by the Cp transition height) at 5 K for Sm+3 AFM ordering is heavily reduced in the case of the superconducting SmFeAsO0.80F0.20 sample.
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U2 - 10.1007/s10948-012-1824-6
DO - 10.1007/s10948-012-1824-6
M3 - Article
AN - SCOPUS:84879090135
SN - 1557-1939
VL - 26
SP - 2383
EP - 2389
JO - Journal of Superconductivity and Novel Magnetism
JF - Journal of Superconductivity and Novel Magnetism
IS - 7
ER -