Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 21: Solids at Low Temperature - Poster Session

TT 21.15: Poster

Wednesday, March 28, 2007, 14:00–17:45, Poster A

Electronic transport properties of C-doped Mn₅Si₃ films — •B. Gopalakrishnan¹, Christoph Sürgers¹, and Hilbert v. Löhneysen^1,2 — ¹Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe — ²Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe

The incorporation of carbon into the antiferromagnetic Mn₅Si₃ compound gives rise to ferromagnetic order with a Curie temperature above room temperature. The microscopic origin of the C-induced ferromagnetism still needs to be explored. Here we report on the electronic transport properties of 100-nm thick Mn₅Si₃C_x (0 ≤ x ≤ 1.2) films prepared by simultaneous magnetron sputtering of elemental Mn, Si, and C [1]. We observe distinct differences in the temperature dependence of the resistance R, magnetoresistance, and Hall effect of the ferromagnetic C-doped films compared to antiferromagnetic Mn₅Si₃. In particular, for films with an optimum doping level x = 0.8 inferred from previous magnetization measurements, we observe a metallic behavior of R and the lowest residual resistivity. At temperatures below 20 K a behavior R ∝ − lnT is found, reminiscent of electron-electron interaction or weak-localization effects, although the films are much thicker than all relevant scattering lengths.

[1] C. Sürgers et al., Phys. Rev. B 68, 174423 (2003)