Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Magnetic Heuslers, Half-Metals and Oxides (jointly with MA)
TT 11.5: Vortrag
Montag, 16. März 2015, 10:30–10:45, H 0112
Superconducting TiN seed layer for Heusler compounds — •Alessia Niesen1, Manuel Glas1, Daniel Ebke2, Jan Schmalhorst1, and Günter Reiss1 — 1Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Germany — 2Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
TiN thin films were prepared by DC and RF magnetron sputtering in an UHV sputtering system. Epitaxial growth was achieved on MgO (001) and SrTiO3 (001) substrates at deposition temperatures above 450∘C. The crystallographic and surface properties of TiN were determined by X-ray diffraction (XRD) and reflection (XRR) measurements. In addition, atomic force microskopy (AFM) was performed to verify the low roughness (<1 nm) measured by the XRR. The out-of-plane lattice constant and the resistivity of TiN reached the theoretical predicted values of 4.24 Å and nearly 20 µ Ω cm (bulk value). 4-terminal transport measurements in a closed cycled helium cryostat showed a phase transition to the superconducting state at temperatures below 5 K for TiN deposited at 450∘C on MgO and SrTiO3 substrate. The suitability of TiN as seed layer for ferromagnetic materials like Iron and Heusler compounds, e. g. Co2FeAl and Mn3−xGa, was investigated by analysing the crystallographic and magnetic properties. Epitaxial growth of both Heusler compounds (Co2FeAl and Mn3−xGa) on a TiN seed layer has been proven for various deposition temperatures. Hall-measurements additionally showed a higher coercitivity and squareness ratio for Mn-Ga thin films when prepared on a TiN buffer.