Institutes | Max Planck Institutes | MPI of Microstructure Physics

Magnons are the wave-like motions of the magnetic moments in a magnetically ordered solid. Similar to other waves, magnons may also be used for information processing. The study of wavelength, frequency and lifetime of magnons in magnetic solids is an important area of research. At the Max Planck Institute of Microstructure Physics the properties of magnons excited at ferromagnetic surfaces are investigated using spin-polarized electron spectroscopy.

2012

Thermoelectric properties of porous silicon

2012, Max Planck Institute of Microstructure Physics

De Boor, Johannes; Ao, Xianyu; Kim, Dong-Sik; Schmidt, Volker

By nanostructuring silicon its thermal conductivity can be significantly reduced. Such a reduction can potentially induce a corresponding increase of the thermoelectric efficiency so that the transformation of heat into electric power could be improved. Therefore porous silicon layers were produced by electrochemical etching and the thermoelectric properties of the nanostructured material investigated. These investigations show that the thermal conductivity is indeed strongly reduced but that due to competing effects only moderate increases of the thermoelectric efficiency can be achieved.

2011

Magnetoelectric coupling at metallic surfaces

2011, Max Planck Institute of Microstructure Physics

Ernst, Arthur; Ostanin, Sergey; Fechner, Michael; Mertig, Ingrid

Magnetoelectric coupling allows changing the magnetic state of a material by applying an electric field. To date, this phenomenon has mainly been observed in insulating materials. Metallic bulk systems do not exhibit this effect, because applied electric fields are screened by conduction electrons. We have been able to switch the magnetic order in a metallic nanostructure reversibly between two stable magnetic states using magnetoelectric coupling induced by an applied electric field.

2010

Photoemission by ultrashort laser pulses

2010, Max Planck Institute of Microstructure Physics

Winkelmann, Aimo; Chiang, Cheng-Tien; Lin, Wen-Chin; Kirschner, Jürgen

The investigation of possibilities to influence electrons in solids and at surfaces on the femtosecond (10^-15 s) time scale is an important area of research. This is also relevant for the steering of magnetic switching processes by ultrashort laser pulses and for the control of the spin of excited electrons. At the MPI of Microstructure Physics, the control of the spin of optically excited photoelectrons is investigated by the absorption of multiple photons at metal surfaces.

2009

Ferroelectric nanocapacitors

2009, Max Planck Institute of Microstructure Physics

Hesse, Dietrich; Alexe, Marin; Han, Hee; Lee, Woo; Lotnyk, Andriy; Senz, Stephan; Schubert, Markus Andreas; Vrejoiu, Ionela; Gösele, Ulrich

Non-volatile solid state memories of high memory density are a promising research field, both under technological and fundamental aspects. Since the size of a single memory cell must be clearly below 100 nanometer, and the properties of storage materials can be considerably modified at such low size, the development of suitable preparation methods and the property analysis of the thus prepared memory cells represent considerable challenges. Such investigations are part of the research on nanostructured materials at Max Planck Institute of Microsctructure Physics in Halle.

2008

Surface Alloys: A Class of Materials with Giant Rashba Spin-Orbit Coupling

2008, Max Planck Institute of Microstructure Physics

Henk, Jürgen

The surface alloy Bi/Ag( 111) exhibits a giant spin splitting of its surface electronic structure due to Rashba spin-orbit coupling. Electronic structure calculations prove that the effect is brought about by an in-plane structural inversion asymmetry in the surface layer, in interplay with the conventional Rashba effect. These findings pave the way for testing theoretical predictions for spin-orbit split two-dimensional electron gases.

2007

Atomic Layer Deposition (ALD)

2007, Max Planck Institute of Microstructure Physics

Knez, Mato; Nielsch, Kornelius; Gösele, Ulrich

Nanostructures are in the focus of research in technology, medicine and biology. The Max Planck Institute of Microstructure Physics in Halle currently develops a major research project which deals with the deposition of thin inorganic films, biological, organic and inorganic nanostructures and the exploitation of such functionalized materials, for applications in medicine, electronics, catalysis, and sensing.

2006

X-ray structure analysis of the Fe/MgO/Fe(001) tunneling-magneto-resistance system

2006, Max Planck Institute of Microstructure Physics

Meyerheim, Holger L.

Using surface sensitive x-ray diffraction the geometric structure of the Fe/MgO/Fe(001) Tunneling-Magneto-Resistance (TMR) device was investigated. Evidence for the formation of an FeO-like interface layer could be provided, which significantly influences the magnitude of the TMR-effect

2005

First principles study of the magnetism of diluted magnetic semiconductors

2005, Max Planck Institute of Microstructure Physics

Sandratskii, Leonid; Patrick Bruno

Modern spin-electronics defines high requirements for the design and fabrication of new materials. Dilute magnetic semiconductors take an important position among the materials that can fulfill these requirements. Here we report on the results of some of our first-principles studies on these materials. We show that partially filled electronic bands play an important role in the magnetism of these systems. The long-range exchange interaction appears as a compromise between the delocalization of the hole states from the 3d impurities and the strength of the 3d-hole interaction. The properties of this compromise depend strongly on the system studied and can be determined only within the framework of the realistic first-principles density-functional-theory calculations

2004

Semiconductor Nanowires

2004, Max Planck Institute of Microstructure Physics

Kolb, Florian M.; Breitenstein, Otwin; Erfurth, Wilfried; Hofmeister, Herbert; Schmidt, Volker; Scholz, Roland; Schubert, Luise; Senz, Stephan; Werner, Peter; Zacharias, Margit; Zakharov, Nikolai; Gösele, Ulrich

Semiconductor nanowires represent a promising research field where basic research and technology meet. The analysis of their growth mechanism, their properties and their possible applications are part of the research at the Max Planck Institute of Microstructure Physics in Halle. Several different growth methods have been applied to fabricate semiconductor nanowires, which were characterized using electron microscopy. Further investigations, e.g. of the electrical and optical properties are currently carried out.