Paulose P L, Jeevan H S, Geibel C, Hossain Z
Department of Physics, Indian Institute of Technology, Kanpur 208016, India.
J Phys Condens Matter. 2009 Jul 1;21(26):265701. doi: 10.1088/0953-8984/21/26/265701. Epub 2009 Jun 5.
Superconductivity is found in 50% K-doped EuFe(2)As(2) samples below 33 K. Our results from electrical resistivity, magnetic susceptibility and (57)Fe and (151)Eu Mössbauer spectroscopy provide clear evidence that the ordering of the Fe moments observed at 190 K in undoped EuFe(2)As(2) is completely suppressed in our 50% K-doped sample; thus there is no coexistence of the Fe magnetic order and the superconducting state. However, short range ordering of the Eu moments coexists with the superconducting state below 15 K. A bump in the susceptibility well below T(c) as well as the broadening of the Fe Mössbauer line below 27 K evidence an interplay between the Eu magnetism and the superconducting state.
在50% K掺杂的EuFe₂As₂样品中，低于33 K时发现了超导性。我们通过电阻率、磁化率以及⁵⁷Fe和¹⁵¹Eu穆斯堡尔谱得到的结果提供了明确的证据，表明在未掺杂的EuFe₂As₂中于190 K观察到的Fe磁矩有序在我们50% K掺杂的样品中被完全抑制；因此不存在Fe磁有序与超导态的共存。然而，Eu磁矩的短程有序在低于15 K时与超导态共存。远低于Tc时磁化率的一个凸起以及低于27 K时Fe穆斯堡尔谱线的展宽证明了Eu磁性与超导态之间的相互作用。
