Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 66: Spintronics (joint session MA/TT)

TT 66.6: Vortrag

Mittwoch, 14. März 2018, 16:15–16:30, EB 202

Dynamics of Mn Local Moments in Metallic and Semiconducting Pnictides — M. A. Surmach¹, P. Y. Portnichenko¹, Z. Deng^2,3, C. Q. Lin^2,4,5, J. K. Glasbrenner⁶, I. I. Mazin⁶, D. L. Sun⁷, Y. Liu⁷, C. T. Lin⁷, A. Ivanov⁸, J. T. Park⁹, J. A. Rodriguez-Rivera^10,11, and •D. S. Inosov¹ — ¹TU Dresden, Germany — ²Inst. of Physics, Beijing — ³Center for High Pressure Sci. & Technol., Beijing — ⁴Univ. of Chinese Academy of Sciences, Beijing — ⁵Collab. Innov. Center of Quantum Matter, Beijing — ⁶Naval Research Lab., Washington, USA — ⁷MPI-FKF, Stuttgart, Germany — ⁸ILL, Grenoble, France — ⁹MLZ, Garching, Germany — ¹⁰Univ. of Maryland, USA — ¹¹NIST Center for Neutron Research, USA

We have investigated the effects of Mn doping in two materials isostructural to 122-type iron-based superconductors by neutron spectroscopy. First, we discuss the excitation spectrum of Mn-substituted BaFe₂As₂, where local magnetic clusters pinned to the impurity sites lead to an emergence of (π,π) magnetic excitations. We discuss their 3D character and the origin of the spin gap. The 2^nd class of materials derives from the isostructural semiconductor BaZn₂As₂, giving rise to a dilute magnetic semiconductor upon Mn substitution. Hole doping by K provides an opportunity to tune the carrier concentration and the amount of magnetic moments independently. The resulting compound, (Ba_1−xK_x)(Zn_1−yMn_y)₂As₂, is a ferromagnet with the maximal Curie temperature of 230 K. It offers a versatility of chemically tailored properties, as the hole doping is decoupled from spin injection and occurs in a different crystallographic layer.