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MA: Magnetismus
MA 15: Magnetische Kopplungsph
änomene / Exchange Bias
MA 15.10: Vortrag
Samstag, 5. März 2005, 16:15–16:30, TU H1028
Detection of Spin and Charge States in Centrosymmetric Materials by Nonlinear Optics — •T. Satoh1,2, Th. Lottermoser1, M. Fiebig1, Y. Ogimoto2,3, H. Tamaru2, M. Izumi2, K. Miyano2, and S. Ishihara4 — 1Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin — 2RCAST, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan — 3Devices Technology Res. Labs., SHARP Corp., Nara, Japan — 4Dept. of Physics, Tohoku University, Sendai 980-8578, Japan
Over the last decade nonlinear optics has evolved into a powerful tool for studying the magnetic properties of matter. We investigated two magnetic systems with multiphoton techniques where linear optical methods fail. (i) The interface of transition metal oxides has attracted recent attention: it represents a 2D electron system in titanates and displays interface ferromagnetism in manganites. Degradation of tunnelling magnetoresistance due to charge transfer at the interface has been suggested. We apply interface sensitive second harmonic generation to manganite thin films and reveal the nature of charge transfer at the interface. The experimental results were compared with theoretical calculations. (ii) Resonance-enhanced sum-frequency generation is introduced as novel tool for investigation of magnetically ordered compounds. A tunable laser at frequency ω1 is used to excite an intermediate electronic transition resonantly while a second laser at frequency ω2 is used to scan the nonlinear spectrum at ω1+ω2. The technique is particularly useful for the investigation of centrosymmetric structures that the majority of magnetic compounds possess. The technique is demonstrated on antiferromagnetic NiO.