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Papers by Claudia Felser

Research paper thumbnail of Substitution Effects in Double Perovskites: How the Crystal Structure Influences the Electronic Properties

Research paper thumbnail of Crystal Structure of Heusler Compounds

Research paper thumbnail of Half-Metallic Ferromagnets

Research paper thumbnail of Heusler Compounds at a Glance

Research paper thumbnail of Hard X-Ray Photoelectron Spectroscopy of New Materials for Spintronics

ABSTRACT In this work, results of hard X-ray photoelectron spectroscopy (HAXPES) of Heusler compo... more ABSTRACT In this work, results of hard X-ray photoelectron spectroscopy (HAXPES) of Heusler compounds and new materials for spintronics are presented. The class of Heusler materials includes some interesting half-metallic and ferromagnetic properties that were predicted by theory. HAXPES allows a direct comparison of the measured and the calculated electronic structure. Valence band spectroscopy of bulk materials by HAXPES is illustrated for the case of the half-metallic ferromagnet Co2MnGe. The feasibility of HAXPES to explore the valence band electronic structure in deeply buried metallic layers is demonstrated for buried Co2MnSi films. The films exhibit the same valence density of states as bulk samples and confirm the promise of an epitaxial, single-crystalline Co2-based Heusler compound film as a ferromagnetic electrode for spintronics devices. The study of complete CoFe(B)/MgO/CoFe(B) tunneling junctions demonstrates the capability of HAXPES to explore the electronic structure in deeply buried layers in a non-destructive way. The improvement of the TMR by annealing of the junction is explained by an improvement of the structure together with a change of the composition in the CoFeB layers.

Research paper thumbnail of New Heusler Compounds and Their Properties

ABSTRACT Spintronics is a multidisciplinary field and a new research area. New materials must be ... more ABSTRACT Spintronics is a multidisciplinary field and a new research area. New materials must be found for satisfying the different types of requirement. The search for stable half-metallic ferromagnets and ferromagnetic semiconductors with Curie temperatures higher than room temperature is still a challenge for solid state scientists. A general understanding of how structures are related to properties is a necessary prerequisite for material design. Computational simulations are an important tool for a rational design of new materials. The new developments in this new field are reported from the point of view of material scientists.

Research paper thumbnail of Topological Insulators–From Materials Design to Reality

Research paper thumbnail of Magnetic transitions in double perovskite Sr {sub 2} FeRe {sub 1-x} Sb {sub x} O {sub 6}(0 {<=} x {<=} 0.9)

Research paper thumbnail of Calculated electronic structure of semiconducting Gd compounds with Half-Heusler and LiGaGe-structure

Research paper thumbnail of Max Planck Inst. of Chem. Phys. for Solids, Dresden, Germany

Research paper thumbnail of Exchange bias up to room temperature in the antiferromagnetic bulk hexagonal Mn3Ge

Research paper thumbnail of Magneto-optical characterization of single crystalline Co2FeAl0. 4Si0. 6 thin films on MgO (1 0 0) substrates with Cr and MgO seed layers

ABSTRACT We report on the experimental investigation of the influence of a seed layer on the magn... more ABSTRACT We report on the experimental investigation of the influence of a seed layer on the magnetic properties of the full-Heusler alloy Co2FeAl0.4Si0.6 (CFAS). The studied magnetic films are grown epitaxially on MgO (1 0 0) substrates with Cr and/or MgO seed layers. By employing magneto-optical Kerr effect magnetometry we show that magnetic anisotropy can be tuned by choosing the proper seed layer. The results on CFAS show an overall uniaxial anisotropy plus a biaxial contribution which depends on the seed layer. In addition, if grown on MgO, a sharp increase in the coercive field HC at a series of angles symmetric with respect to the easy axis is present. Scanning Kerr-microscope imaging is performed during the magnetization reversal process in order to reveal the type of magnetic domain formation taking place at these angles.

Research paper thumbnail of Rich diversity of single-ion magnet features in the linear OCu III O− ion confined in the hexagonal channels of alkaline-earth phosphate apatites

Following our recent discovery of slow spin relaxation in the unique [OCu(III)O](-) anion located... more Following our recent discovery of slow spin relaxation in the unique [OCu(III)O](-) anion located in the apatite-type pigment A10(PO4)6(CuxOH1-x-y)2, where A = Sr, we present the magnetic behavior of this anion for the cases of A = Ca and Ba, which provides evidence for a cation field impact on the properties of a single-ion magnet molecular anion.

Research paper thumbnail of Contributions Dedicated to Professor Gerd Meyer on the Occasion of His 65th Birthday

Research paper thumbnail of Electrical devices formed using ternary semiconducting compounds

Research paper thumbnail of On the superconductivity of TiNCl and ZrNCl: A local bonding perspective

ABSTRACT We analyze the superconductors TiNCl and ZrNCl from a local bonding perspective. Althoug... more ABSTRACT We analyze the superconductors TiNCl and ZrNCl from a local bonding perspective. Although TiNCl crystallizes in an orthorhombic structure and ZrNCl crystallizes in a hexagonal structure, both compounds show significant structural similarities, for example that both consist of layered metal-Nitrogen networks. The local bonding in those two structures is very similar, giving rise to a dispersive conduction band mostly consisting of metal-d -states. Upon doping both compounds show structural changes, which lead to short metal-metal distances, indicating a bonding interaction that might be important for the appearance of superconductivity in these systems. We furthermore draw analogies to other superconductors that are close to a charge density wave instability around a d 1 -configuration and offer a different perspective on this class of superconductors, which show non-BCS-like superconductivity.

Research paper thumbnail of Erratum

Research paper thumbnail of Guidelines for understanding cubic manganese-rich Heusler compounds

Research paper thumbnail of Topological insulators

Research paper thumbnail of Chemical disorder as an engineering tool for spin-polarization

Research paper thumbnail of Substitution Effects in Double Perovskites: How the Crystal Structure Influences the Electronic Properties

Research paper thumbnail of Crystal Structure of Heusler Compounds

Research paper thumbnail of Half-Metallic Ferromagnets

Research paper thumbnail of Heusler Compounds at a Glance

Research paper thumbnail of Hard X-Ray Photoelectron Spectroscopy of New Materials for Spintronics

ABSTRACT In this work, results of hard X-ray photoelectron spectroscopy (HAXPES) of Heusler compo... more ABSTRACT In this work, results of hard X-ray photoelectron spectroscopy (HAXPES) of Heusler compounds and new materials for spintronics are presented. The class of Heusler materials includes some interesting half-metallic and ferromagnetic properties that were predicted by theory. HAXPES allows a direct comparison of the measured and the calculated electronic structure. Valence band spectroscopy of bulk materials by HAXPES is illustrated for the case of the half-metallic ferromagnet Co2MnGe. The feasibility of HAXPES to explore the valence band electronic structure in deeply buried metallic layers is demonstrated for buried Co2MnSi films. The films exhibit the same valence density of states as bulk samples and confirm the promise of an epitaxial, single-crystalline Co2-based Heusler compound film as a ferromagnetic electrode for spintronics devices. The study of complete CoFe(B)/MgO/CoFe(B) tunneling junctions demonstrates the capability of HAXPES to explore the electronic structure in deeply buried layers in a non-destructive way. The improvement of the TMR by annealing of the junction is explained by an improvement of the structure together with a change of the composition in the CoFeB layers.

Research paper thumbnail of New Heusler Compounds and Their Properties

ABSTRACT Spintronics is a multidisciplinary field and a new research area. New materials must be ... more ABSTRACT Spintronics is a multidisciplinary field and a new research area. New materials must be found for satisfying the different types of requirement. The search for stable half-metallic ferromagnets and ferromagnetic semiconductors with Curie temperatures higher than room temperature is still a challenge for solid state scientists. A general understanding of how structures are related to properties is a necessary prerequisite for material design. Computational simulations are an important tool for a rational design of new materials. The new developments in this new field are reported from the point of view of material scientists.

Research paper thumbnail of Topological Insulators–From Materials Design to Reality

Research paper thumbnail of Magnetic transitions in double perovskite Sr {sub 2} FeRe {sub 1-x} Sb {sub x} O {sub 6}(0 {<=} x {<=} 0.9)

Research paper thumbnail of Calculated electronic structure of semiconducting Gd compounds with Half-Heusler and LiGaGe-structure

Research paper thumbnail of Max Planck Inst. of Chem. Phys. for Solids, Dresden, Germany

Research paper thumbnail of Exchange bias up to room temperature in the antiferromagnetic bulk hexagonal Mn3Ge

Research paper thumbnail of Magneto-optical characterization of single crystalline Co2FeAl0. 4Si0. 6 thin films on MgO (1 0 0) substrates with Cr and MgO seed layers

ABSTRACT We report on the experimental investigation of the influence of a seed layer on the magn... more ABSTRACT We report on the experimental investigation of the influence of a seed layer on the magnetic properties of the full-Heusler alloy Co2FeAl0.4Si0.6 (CFAS). The studied magnetic films are grown epitaxially on MgO (1 0 0) substrates with Cr and/or MgO seed layers. By employing magneto-optical Kerr effect magnetometry we show that magnetic anisotropy can be tuned by choosing the proper seed layer. The results on CFAS show an overall uniaxial anisotropy plus a biaxial contribution which depends on the seed layer. In addition, if grown on MgO, a sharp increase in the coercive field HC at a series of angles symmetric with respect to the easy axis is present. Scanning Kerr-microscope imaging is performed during the magnetization reversal process in order to reveal the type of magnetic domain formation taking place at these angles.

Research paper thumbnail of Rich diversity of single-ion magnet features in the linear OCu III O− ion confined in the hexagonal channels of alkaline-earth phosphate apatites

Following our recent discovery of slow spin relaxation in the unique [OCu(III)O](-) anion located... more Following our recent discovery of slow spin relaxation in the unique [OCu(III)O](-) anion located in the apatite-type pigment A10(PO4)6(CuxOH1-x-y)2, where A = Sr, we present the magnetic behavior of this anion for the cases of A = Ca and Ba, which provides evidence for a cation field impact on the properties of a single-ion magnet molecular anion.

Research paper thumbnail of Contributions Dedicated to Professor Gerd Meyer on the Occasion of His 65th Birthday

Research paper thumbnail of Electrical devices formed using ternary semiconducting compounds

Research paper thumbnail of On the superconductivity of TiNCl and ZrNCl: A local bonding perspective

ABSTRACT We analyze the superconductors TiNCl and ZrNCl from a local bonding perspective. Althoug... more ABSTRACT We analyze the superconductors TiNCl and ZrNCl from a local bonding perspective. Although TiNCl crystallizes in an orthorhombic structure and ZrNCl crystallizes in a hexagonal structure, both compounds show significant structural similarities, for example that both consist of layered metal-Nitrogen networks. The local bonding in those two structures is very similar, giving rise to a dispersive conduction band mostly consisting of metal-d -states. Upon doping both compounds show structural changes, which lead to short metal-metal distances, indicating a bonding interaction that might be important for the appearance of superconductivity in these systems. We furthermore draw analogies to other superconductors that are close to a charge density wave instability around a d 1 -configuration and offer a different perspective on this class of superconductors, which show non-BCS-like superconductivity.

Research paper thumbnail of Erratum

Research paper thumbnail of Guidelines for understanding cubic manganese-rich Heusler compounds

Research paper thumbnail of Topological insulators

Research paper thumbnail of Chemical disorder as an engineering tool for spin-polarization

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