Publications (8)7.87 Total impact
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Article: In-plane magnetic anisotropy of Fe atoms on Bi$_2$Se$_3$(111)
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ABSTRACT: The robustness of the gapless topological surface state hosted by a 3D topological insulator against perturbations of magnetic origin has been the focus of recent investigations. We present a comprehensive study of the magnetic properties of Fe impurities on a prototypical 3D topological insulator Bi$_2$Se$_3$ using local low temperature scanning tunneling microscopy and integral x-ray magnetic circular dichroism techniques. Single Fe adatoms on the Bi$_2$Se$_3$ surface, in the coverage range $\approx 1%$ are heavily relaxed into the surface and exhibit a magnetic easy axis within the surface-plane, contrary to what was assumed in recent investigations on the opening of a gap. Using \textit{ab initio} approaches, we demonstrate that an in-plane easy axis arises from the combination of the crystal field and dynamic hybridization effects.12/2011; -
Article: Temperature-dependent Néel wall dynamics in GaMnAs/GaAs
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ABSTRACT: Extensive Kerr microscopy studies reveal strongly temperature-dependent domain wall (DW) dynamics in Hall bars made from compressively strained GaMnAs. Depending on the temperature, magnetic charging of the DWs is observed, and the nucleation rates depend on the Hall geometry with respect to the crystal axes. Above a critical temperature where a biaxial-to-uniaxial anisotropy transition occurs, a drastic increase in nucleation events is observed. Below this temperature, the nucleation of domains tends to be rather insensitive to temperature. This spatially resolved study of the DW dynamics in patterned GaMnAs at variable temperature has important implications for potential applications in single DW magneto-logic devices made from ferromagnetic semiconductors.New Journal of Physics 09/2010; 12(9):093022. · 4.18 Impact Factor -
Article: Manipulation of electrical and ferromagnetic properties of photo-sensitized (Ga,Mn)As
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ABSTRACT: We present the manipulation of magnetic and electrical properties of (Ga,Mn)As by the adsorption of dye-molecules as a first step towards the realization of light-controlled magnetic-semiconductor/dye hybrid devices. A significant lowering of the Curie temperature with a corresponding increase in electrical resistance and a higher coercive field is found for the GaMnAs/fluorescein system with respect to (Ga,Mn)As. Upon exposure to visible light a shift in Curie temperature towards higher values and a reduction of the coercive field can be achieved in photo-sensitized (Ga,Mn)As. A mayor change in the XPS spectrum of (Ga,Mn)As indicates the appearance of occupied levels in the energy range corresponding to the (Ga,Mn)As valence band states upon adsorption of fluorescein. This points towards a hole quenching effect at the molecule-(Ga,Mn)As interface which is susceptible to light exposure. Comment: 4 pages, 4 figures06/2010; -
Article: Complex magnetic phase in submonolayer Fe stripes on Pt(997)
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ABSTRACT: Correlations between magnetism and morphology of iron nanostructures of monatomic height on Pt(997) substrates are studied using x-ray magnetic circular dichroism as well as scanning tunneling microscopy and helium scattering. A drastic collapse of the average magnetization by more than a factor of 4 is observed when increasing the iron coverage from 0.1 to 0.2 ML. This effect goes along with a softening of the magnetic anisotropy energy and a gradual reorientation of the magnetic easy axis from in plane to out of plane. The experimental findings together with electronic density-functional calculations suggest the formation of a complex magnetic phase in corrugated rim regions of Fe islands, leading to both ferromagnetic and antiferromagnetic exchange couplings of Fe moments depending on their various local bonding configurations.Physical Review B 03/2009; 79(10):104430. · 3.69 Impact Factor -
Article: Complex domain wall dynamics in compressively strained GaMnAs epilayers
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ABSTRACT: The domain wall induced reversal dynamics in compressively strained GaMnAs was studied employing the magneto-optical Kerr effect and Kerr microscopy. Due to the influence of an uniaxial part in the in-plane magnetic anisotropy (90+/-Delta) domain walls with considerably different dynamic behavior are observed. While the (90+Delta) reversal is identified to be propagation dominated with a small number of domain walls, the case of (90-Delta) reversal includes the nucleation of many domain walls. The domain wall nucleation/propagation energy for both transitions are estimated using model calculations from which we conclude that single domain devices can be achievable using the (90+Delta) mode. Comment: 4 figures05/2008; -
Article: Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface
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Article: Polarized Neutron Reflectometry Study of the Magnetization Reversal Process in YBa2Cu3O7/La2/3Ca1/3MnO3 Superlattices Grown on SrTiO3
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Article: Magnetic aftereffect in compressively strained GaMnAs studied using Kerr microscopy
Physical Review B, v.81 (2010).
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Institutions
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2008–2010
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Max-Planck-Institut für Festkörperforschung
Stuttgart, Baden-Wuerttemberg, Germany
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