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DF: Fachverband Dielektrische Festkörper

DF 22: Poster II

DF 22.5: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Manipulating the Heat Conductivity of La_0.67Ca_0.33MnO₃ using External Magnetic Fields — •Christoph Euler, Christian Mix, Tino Jäger, Ramudu Machavarapu, Mathias Kläui, and Gerhard Jakob — University of Mainz, Germany

Recently research has been conducted on the interaction between electron spin and heat conduction. It was shown that heat currents can generate spin currents in magnetic nanostructures, which in turn can manipulate the magnetization [1]. Such spin-caloric mechanisms are frequently studied in thin films.
La_0.67Ca_0.33MnO₃ (LCMO) is a doped manganese oxide displaying huge magnetoresistivity (CMR)[2]. LCMO is a paramagnetic insulator above T_C≈ 230 K and ferromagnetic and semiconducting below. LCMO films (d≈ 200 nm) are deposited on SrTiO₃ substrates using pulsed laser deposition in an O₂ atmosphere. The samples are characterized using XRD, AFM and VSM. A 3ω method is then used to determine the out-of-plane thermal conductivity.
The transport properties of LCMO have been studied previously [3]. In a material displaying CMR, by virtue of the Wiedemann-Franz law it should also be possible to modify the heat conductivity of a sample by applying external magnetic fields in a low-temperature magnetic cryostat. First results of the thermal conductivity are presented.
[1] K. Uchida et al., Nature 455, 778 (2008).
[2] R. von Helmolt et al., Phys. Rev. Lett. 71 (1993) 2331.
[3] G. Jakob et al., Phys. Rev. B58 (1998) 14966.