Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.67: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Spin-lattice relaxation phenomena in manganite La_0.7Sr_0.3MnO₃ thin films — •Markus C. Weber¹, Vasily Moshnyaga², Konrad Samwer², and Burkard Hillebrands¹ — ¹Fachbereich Physik und Forschungsschwerpunkt MINAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 56, 67663 Kaiserslautern, Germany — ²I. Physikalisches Institut, Universität Göttingen, Bunsenstr. 9, 37073 Göttingen, Germany

All-optical pump-probe experiments employing magneto-optics as a probe were performed to study spin and lattice relaxation dynamics in thin epitaxial La_0.7Sr_0.3MnO₃ films. The perovskite manganites were grown by a metalorganic aerosol deposition technique [1] onto MgO substrates. The films reveal a ferromagnetic-paramagnetic phase transition at a Curie temperature of about T_C = 360 K. Upon photoexcitation the spin temperature is elevated close to or even above T_C. By properly choosing the pump pulse energy it is possible to demagnetize the sample completely within the pump pulse width (τ = 8.3 ps), associated with a collapse of the remanence. Two distinct recovery regimes of the ferromagnetic order can be resolved upon arrival of the pump pulse, which manifest themselves by two different relaxation times. A pump pulse energy independent spin-lattice relaxation time of about 200 ps can be deduced from the real time evolution of the remanence. One dimensional heat flow out of the manganite film into the substrate with a time constant of about 0.5 ns up to 1 ns depending on the pump pulse energy sets the ultimate speed of recovery of the ferromagnetic order.

[1] V. Moshnyaga et al., Appl. Phys. Lett. 74, 2842 (1999).