Regensburg 1998 – wissenschaftliches Programm
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AM: Magnetismus
AM 17: Magnetische Phasenübergänge in drei- und niederdimensionalen Strukturen
AM 17.13: Vortrag
Donnerstag, 26. März 1998, 13:15–13:30, H23
Size-dependent thermoelectric power in mesoscopic AuFe spinglass wires — •C. Strunk1, M. Henny1, G. Neuttiens2, J. Eom3, V. Chandrasekhar3, C. Van Haesendonck2, and C. Schönenberger1 — 1Institut für Physik, Universität Basel, CH-4056 Basel — 2Lab. v. Vaste Stoffysica en Magnetisme, B-3001 Leuven — 3Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
We present a new method for measuring the thermoelectric power of dilute magnetic alloys on a mesoscopic scale. Thermocouples consisting of a wide and a narrow wire of width dW and dN, respectively, are formed between a heater and macrosopic contact pads. The structures are made by electron beam lithography from 3000 ppm AuFe on oxidized Si wafers. The electron temperature Tel of the heater is controlled by a dc-bias current Idc and measured using noise thermometry. The heating current induces a dV/dIdc curve which is antisymmetric in Idc [1] and is directly related to the thermopower difference Δ S(T) between the narrow and the wide wire. Δ S(T) systematically increases when dN is reduced from 400 to 100 nm, while dW is fixed at 400nm. Our results provide new experimental evidence for the ongoing debate on the size dependence of the spin scattering in dilute magnetic alloys [2].
[1] J. Eom et al., Phys. Rev. Lett. 77, 2276 (1996).
[2] G. Chen and N. Giordano, Phys. Rev. Lett. 66, 209 (1991), J. F. DiTusa et al. Phys. Rev. Lett. 68, 678 (1992), V. Chandrasekhar et al., Phys. Rev. Lett. 72, 2053 (1994).