Furkan Bulut - Academia.edu (original) (raw)

Papers by Furkan Bulut

In this work, conjugated block copolymer polyfluorene/polyaniline (PF/PANI) has been studied as a... more In this work, conjugated block copolymer polyfluorene/polyaniline (PF/PANI) has been studied as a potential candidate for photovoltaic applications. We used two techniques based on nanoimprint lithography (NIL) for phase alignment of this block copolymer blend PF/PANI, polyaniline being the donor and polyfluorene -the acceptor phase. In the first technique, metallic nanostructures induce nanostructuring in the polymer layer, whereas in the second technique, the PF/PANI is directly patterned with a stamp. The electrical and photoelectrical properties of the polymeric systems were studied and the morphology was characterized by AFM and SEM.

physica status solidi (b), 2010

Macromolecular Symposia, 2004

... Sotomayor Torres,2 U. Scher/*1 1 Universität Potsdam, Institut für Chemie, Karl-Liebknecht-St... more ... Sotomayor Torres,2 U. Scher/*1 1 Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Str. 24/25, Haus 25, 14476 Golm, Germany E-mail: scherf@rz.uni-potsdam.de 2 BUGH Wuppertal, FB Elektrotechnik, Gaußstr.20, 42097 Wuppertal ... [3] AR Brown, С P. Jarrett, DM Deleeuw ...

Journal of Physics: …, Jan 1, 2008

Mass-filtered Fe and FeCo nanoparticles are deposited under soft-landing and ultra-high vacuum co... more Mass-filtered Fe and FeCo nanoparticles are deposited under soft-landing and ultra-high vacuum conditions on the bare W(110) surface. The structure and the stoichiometry of FeCo alloy nanoparticles are determined by ex situ high resolution transmission electron microscopy (HRTEM) and energy-dispersive x-ray spectroscopy (EDX) on single nanoparticles, respectively, proving a crystalline structure. In situ scanning tunneling microscopy (STM) shows that the clusters are irregularly distributed on the W(110) surface, that no fragmentation occurs, that steps do not act as preferential adsorption sites, and yields strong evidence for a partial flattening of the particles upon deposition. The magnetic anisotropy energy (MAE) of mass-filtered pure Fe nanoparticles is investigated by means of x-ray magnetic circular dichroism (XMCD) at the iron L3 edge. The magnetization loops reveal an uniaxial magnetic anisotropy with the magnetic hard axis being perpendicular to the surface. The experimentally determined MAE is compared to calculated shape and interface anisotropy contributions of partially flattened nanoparticles according to the STM observations on the FeCo clusters.

Journal of Physics: Conference Series, 2010

A continuously working arc cluster ion source was used to prepare mass-filtered Fe nanoparticles ... more A continuously working arc cluster ion source was used to prepare mass-filtered Fe nanoparticles with a mean size of 6 to 10 nm. Their structure was determined by HRTEM. The nanoparticles were deposited into an Al matrix and additionally on a W(110) substrate for comparison. Within the matrix they maintain their spherical shape and do not show any magnetic anisotropic effect. For uncapped Fe nanoparticles on a tungsten surface, a flattening is observed by STM and the nanoparticles exhibit a distinct magnetic anisotropy with the easy magnetization axis being in the surface plane. Correlating both investigations we conclude that this observation is due to shape and interface-induced contributions to the magnetic anisotropy.

Applied Physics A, 2009

Size-selected iron and iron-cobalt alloy clusters have been studied with high resolution transmis... more Size-selected iron and iron-cobalt alloy clusters have been studied with high resolution transmission electron microscopy (HRTEM) and scanning tunneling microscopy (STM). The clusters were produced by a continuously working arc cluster ion source and subsequently size-selected by an electrostatic quadrupole deflector. The crystalline structure of pure clusters has been investigated with HRTEM to ensure a reliable determination of the lattice parameter for the alloy clusters. The composition of the alloy clusters was checked with energy dispersive X-ray spectroscopy (EDX). The height of the deposited FeCo clusters on the (110) surface of tungsten was determined via STM. These results were compared with the lateral size distribution being investigated by TEM and allow a conclusion on the shape of the deposited alloy clusters. Furthermore, the behavior of the alloy clusters on the W(110) surface at elevated temperatures has been examined, at which the clusters show anisotropic spreading.

… A: Materials Science & …, Jan 1, 2006

Mass-filtered cobalt clusters with a size between 5 nm and 12 nm have been deposited in situ unde... more Mass-filtered cobalt clusters with a size between 5 nm and 12 nm have been deposited in situ under soft-landing conditions onto epitaxially ordered iron and nickel films. The spin and orbital moments of both the clusters as well as the substrate films have been investigated using the element-specific method of X-ray magnetic circular dichroism in photoabsorption. Here, the ferromagnetic films with in-plane magnetic anisotropies have been used to magnetize the clusters remanently without applying external magnetic fields during the measurements. Experimental results from the cobalt clusters are discussed with respect to the different substrates. Furthermore, the influence of oxygen exposure on the spin and orbital moments of cobalt clusters has been investigated in in situ oxidation experiments.

Applied Physics A, 2006

The magnetic properties of 3d-metal clusters significantly differ from bulk behavior. This phenom... more The magnetic properties of 3d-metal clusters significantly differ from bulk behavior. This phenomenon is caused by a narrowing of electronic states and the high ratio of surface to volume atoms giving rise to enhanced magnetic orbital moments. FeCo alloys as soft magnetic materials are known to exhibit very high magnetic moments. The spin and orbital moments of iron and cobalt in size-selected FeCo alloy clusters on non-magnetic as well as magnetized nickel substrates have been investigated by X-ray magnetic circular dichroism (XMCD) with elemental specification. Structural properties were determined by scanning probe measurements. The preformed clusters maintain their original three-dimensional shape with a tendency to a slightly oblate occurrence which can be explained by particle-support interaction and do not change to a more or less two-dimensional formation after deposition.

The European Physical …, Jan 1, 2007

Mass-filtered cobalt clusters with a size of 8nm have been deposited in-situ under soft-landing c... more Mass-filtered cobalt clusters with a size of 8nm have been deposited in-situ under soft-landing conditions onto Au(111). The spin and orbital moments of the Co nanoparticles on a Au (111) single crystal have been investigated as a function of the temperature using the element-specific method of X-ray magnetic circular dichroism in photoabsorption. The results hint at an temperature-dependent spin-reorientation transition which is discussed with respect to different contribution to the magnetic anisotropy. Furthermore, by means of an in-situ oxidation experiment, the influence of an exposure to oxygen on the properties of the cobalt clusters has been investigated.