Khasanov R, Maisuradze A, Maeter H, Kwadrin A, Luetkens H, Amato A, Schnelle W, Rosner H, Leithe-Jasper A, Klauss H-H
Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
Phys Rev Lett. 2009 Aug 7;103(6):067010. doi: 10.1103/PhysRevLett.103.067010.
Using muon-spin rotation, we studied the in-plane (lambda_{ab}) and the out of plane (lambda_{c}) magnetic field penetration depth in SrFe_{1.75}Co_{0.25}As_{2} (T_{c} approximately 13.3 K). The penetration depth anisotropy gamma_{lambda} = lambda_{c}/lambda_{ab} increases from gamma_{lambda} approximately 2.1 at T_{c} to 2.7 at 1.6 K. The mean internal field in the superconducting state increases with decreasing temperature, just opposite to the diamagnetic response seen in magnetization experiments. This unusual behavior suggests that the external field induces a magnetic order which is maintained throughout the whole sample volume.
利用μ子自旋旋转技术，我们研究了SrFe₁.₇₅Co₀.₂₅As₂（Tc约为13.3 K）的面内（λab）和面外（λc）磁场穿透深度。穿透深度各向异性γλ = λc/λab从Tc时的γλ约为2.1增加到1.6 K时的2.7。超导态下的平均内场随温度降低而增加，这与磁化实验中观察到的抗磁响应正好相反。这种不寻常的行为表明，外场诱导了一种在整个样品体积中保持的磁有序。
