title: Slow Spin Dynamics in Superconducting Ca0.9Ce0.1Fe2As2.
abstract: Slow spin dynamics has been observed in superconducting under-doped Ca0.9Ce0.1Fe2As2 single crystal. Below 100 K, the system exhibits hysteresis in the cooling and warming protocols of temperature dependent resistivity due to first order tetragonal to orthorhombic structural transition with simultaneous magnetic transition from paramagnetic to spin density wave antiferromagnetic state of the iron (Fe) ions. Zero field cooled/field cooled (ZFC/FC) magnetization curves showed splitting at 32 K followed by a sharp increase of the FC curve and then FC plateau at low temperatures. Slow spin relaxation in both the ZFC and FC protocols was observed which is typical for spin-glass system. The system also showed features analogue to spin-glass behavior such as ZFC peak, FC plateau, ZFC slow spin relaxation, magnetic hysteresis, and ZFC ac memory effect. The spin-glass like behavior was rather weak and vanished at higher fields. The origin of the slow spin dynamics could be the inhomogeneous distribution of the cerium (Ce) spins ordered along the c-axis OR interactions between Fe and Ce spins which lead to magnetic frustration of Ce spins. All these findings support the coexistence of slow spin dynamics of Ce spins and superconductivity in Ca0.9Ce0.1Fe2As2 single crystal.
authors.affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China [2] Department of Physics, International Islamic University, H-10, Islamabad 44000, Pakistan.
authors.forename: K
authors.initials: K
authors.lastname: Nadeem
authors.affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China [2] School of Physical Science and Technology &Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China.
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.
authors.forename: D Y
authors.initials: DY
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.
authors.forename: Z A
authors.initials: ZA
authors.lastname: Ren
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China.
authors.forename: X G
authors.initials: XG
authors.lastname: Qiu