Studium spinové relaxace v GaAs/AlGaAs heterostruktuře a quench-přepínání v antiferomagnetu CuMnAs ultrarychlými optickými metodami

Surýnek, Miloslav

ii Title: Ultrafast Optical Investigation of Spin Relaxation in GaAs/AlGaAs heterostructure and Quench Switching in Antiferromagnetic CuMnAs Author: Miloslav Surýnek Department: Department of Chemical Physics and Optics Supervisor: prof. RNDr. Petr Němec, Ph.D., Department of Chemical Physics and Optics Abstract: This thesis investigates ultrafast spin-related dynamics in a semiconductor GaAs/AlGaAs heterostructure and in a thin layer of antiferromagnetic metal CuMnAs using a variety of pump-probe experiments. Study of the GaAs/AlGaAs interfacial electron subsystem with an exceptionally long spin lifetime led to the demonstration that spin polarization can be optically erased on a picosecond timescale. In CuMnAs, an effect termed "quench switching" was discovered, in which absorption of a femtosecond laser pulse heats the material to the vicinity of the Néel temperature and subsequent rapid cooling drives it into a metastable magnetically disordered state with higher resistance (up to 20% at room temperature). We experimentally separated the heat-related and magnetic-related components of resistance dynamics, which occur on very different timescales (picosecond to nanosecond, and millisecond to second, respectively) and can serve as a form of short- and long-term memory in a single analog memory device. We...

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