TY - JOUR
T1 - Magnetic and Mössbauer studies of Ba(Fe 1-x Ni x ) 2As 2 single crystals
AU - Felner, I.
AU - Nowik, I.
PY - 2011/5
Y1 - 2011/5
N2 - Magnetization and 57Fe Mössbauer effect spectroscopy (MS) studies of Ba(Fe 1-x Ni x ) 2As 2 single crystals (x=0 to 0.054) at temperatures (5 K to 300 K) have been performed. Magnetic measurements show that for BaFe 2As 2 the magnetic moment decreases below T N=136 K. T N is suppressed monotonically by Ni doping. On the other hand, for higher x values the magnetic moment increases below T N. Unexpectedly for x=0.024 (T N=67 K), the virgin zero-field-cooled (ZFC) curve is higher than that of field-cooled (FC) one below 48 K. The magnetic MS spectra of this sample are composed of a superposition of two subspectra, corresponding to commensurate and incommensurate field distributions. The average magnetic hyperfine field H eff decreases with T and becomes zero at 80 K. For higher x values, the samples become superconducting at T C=15.5 and 19 K for x=0.046 and 0.054, respectively. For both samples below T C, the FC curves are positive (the paramagnetic Meissner effect) up to applied field of H∼15 Oe and the susceptibility is inversely proportional to H. The MS spectra below and above T C are almost identical, indicating that the MS parameters are not sensitive enough to detect the superconducting state. The peculiar phenomena observed are attributed to disorder induced by the presence of Ni atoms in the Fe sublattice.
AB - Magnetization and 57Fe Mössbauer effect spectroscopy (MS) studies of Ba(Fe 1-x Ni x ) 2As 2 single crystals (x=0 to 0.054) at temperatures (5 K to 300 K) have been performed. Magnetic measurements show that for BaFe 2As 2 the magnetic moment decreases below T N=136 K. T N is suppressed monotonically by Ni doping. On the other hand, for higher x values the magnetic moment increases below T N. Unexpectedly for x=0.024 (T N=67 K), the virgin zero-field-cooled (ZFC) curve is higher than that of field-cooled (FC) one below 48 K. The magnetic MS spectra of this sample are composed of a superposition of two subspectra, corresponding to commensurate and incommensurate field distributions. The average magnetic hyperfine field H eff decreases with T and becomes zero at 80 K. For higher x values, the samples become superconducting at T C=15.5 and 19 K for x=0.046 and 0.054, respectively. For both samples below T C, the FC curves are positive (the paramagnetic Meissner effect) up to applied field of H∼15 Oe and the susceptibility is inversely proportional to H. The MS spectra below and above T C are almost identical, indicating that the MS parameters are not sensitive enough to detect the superconducting state. The peculiar phenomena observed are attributed to disorder induced by the presence of Ni atoms in the Fe sublattice.
KW - Paramagnetic Meissner effect
KW - Spin wave density
KW - Superconductivity
UR - http://www.scopus.com/inward/record.url?scp=79957507450&partnerID=8YFLogxK
U2 - 10.1007/s10948-010-0834-5
DO - 10.1007/s10948-010-0834-5
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AN - SCOPUS:79957507450
SN - 1557-1939
VL - 24
SP - 1363
EP - 1369
JO - Journal of Superconductivity and Novel Magnetism
JF - Journal of Superconductivity and Novel Magnetism
IS - 4
ER -