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Projects B1-B9

A [1] [3] [4] [5] [6] [7] [8]     B [1] [2] [3] [4] [6] [7] [8] [9]     C [1] [2] [5] [7] [8] [9]     Z [3] [4]

 

B1 Interaction of exciton, carrier and dangling bond spins in colloidal nanostructures

Principal investigators:

Associated: Dr. Elena Shornikova (TU Dortmund)

Summary:

In this project, we will study optical spin orientation and spin dephasing with ultrafast magneto-optical techniques. These concepts will be applied to a broad range of materials, ranging from epitaxial semiconductors to novel nanocrystals. The overarching aspect is the investigation of structures which exhibit much longer carrier lifetimes when compared to most direct-gap bulk materials and nanostructures. To this end, we will investigate material systems featuring indirect transitions. Important examples comprise group IV bulk materials and heterostructures as well as (In,Al)As/AlAs and CdSe/CdS quantum dots.

 

B2 Spin-flip Raman scattering for studying spin interactions

Principal investigators:

Summary:

The project focuses on characterization of spin level structures and spin-based interactions of neutral and charged exciton complexes in magnetic and nonmagnetic semiconductor nanostructures as well as hybrid semiconductor/ferromagnet structures. Carrier-carrier exchange interactions and carrier-nuclear hyperfine interactions will be studied by resonant spin-flip Raman scattering. Symmetry dependences will be examined either by external strain application or via changing the internal strain in quantum dots with different annealing, thus providing novel insights into scattering mechanisms and their efficiencies.

 

B3 Optical generation and detection of spin transport

Principal investigators:

Associated: Dr. Alexander Poshakinskiy (Ioffe Institute)

Summary:

The project aims to investigate experimental and theoretical concepts to optically induce and detect spin currents. While diffusive spin currents are formed from spin-polarized carriers subject to electric fields, the generation of ballistic spin currents relies on quantum interference control. The analysis of the resulting spin motion is achieved by optical Kerr microscopy. We want to advance those ideas to important material classes encompassing dilute magnetic semiconductors as well as ferromagnets and antiferromagnets.

 

B4 Spin interactions between magnetic ions and carriers

Principal investigators:

Associated: Dr. Arne Ludwig (Ruhr-Universität Bochum)

Summary:

The project focuses on studying spin interactions between magnetic ions and conduction-band and valence-band carriers in semiconductor nanostructures doped with both manganese as well as rare-earth ions. The key factor for understanding the, in particular, exchange interactions is their scaling with external fields and the concentrations of the magnetic ions and carriers. The impact of two-dimensional carrier gases on the magnetic ion spins with respect to collective spin phenomena like the topological Hall and Kondo effect will be studied. These studies will be rounded off by investigating spin interactions, merely of photo-induced magnetic polarons, in intrinsically magnetic europium chalcogenides.

 

B7 Spin-dependent polariton condensates

Principal investigators:

Associated: Prof. Dr. Vladimir Kalevich (St. Petersburg State University)

Summary:

This project is focused on using the spin-anisotropic polariton-polariton interaction to create spin-sensitive all-optical circuit-like switches or other logical elements. Thus, we will utilize spin as an additional degree of freedom in optical information processing. The concept of “polariton neurons” as proposed by us as building blocks of polariton integrated circuits will be checked experimentally. We will demonstrate basic polariton logic elements, thereby paving the way towards spin-sensitive optical circuits that are also inscribed optically and can therefore be created and modified on demand.

 

B8 fs-manipulation of charge-magnetism coupling in an antiferromagnetic semiconductor

Principal investigators:

Summary:

The main goal of project B8 is to realize femtosecond spin-to-charge and charge-to-spin conversion in an AF semiconductor.The intrinsic physical complexity of our project demands both a thorough investigation of the ground state of our sample material and a tight collaboration between experiments and theory. Experimentally, we will implement a procedure allowing to disclose the real-time evolution of both the spin and charge systems. Theoretically, state-of-the-art modelling is needed to achieve a comprehensive understanding of the equilibrium and non-equilibrium relevant properties, since they are both generated by many body effects, electronic correlations and spin-charge coupling which are all notoriously arduous to handle.

 

B9 Ultrafast control of spins in magnetically ordered 2D materials

Principal investigators:

Associated: Dr. Valery Davydov and Dr. Nikolay Khokhlov (Ioffe Institute)

Summary:

The goal of Project B9 is the ultrafast manipulation of the magnetic order in 2D few-layers-thin AF semiconductors. First, we will characterize them extensively, analyzing the structural, magnetic and electronic properties of the ground state by means of a wide variety of spectroscopic approaches (Raman, optical, magneto-optical, photoemission, moment-spectromiscroscopy) utilised as a function of several experimental parameters (magnetic and electric field, temperature). Then, we will employ the knowledge developed in the characterization phase to optically manipulate spin on the ultrafast timescale. The results of this project will directly address the fundamental question concerning the feasibility of ultrafast control of the magnetic order in low-dimensional magnets.



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ICRC - TRR 160
Katharina Sparka
Technische Universität Dortmund
Otto-Hahn-Straße 4a
D-44227 Dortmund
Germany

 

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Phone +49 (0)231 755 2041
Fax +49 (0)231 755 3674

 

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