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16 results on '"Groessinger, Roland"'

1. Field-induced Magnetic Transition in Cobalt-Ferrite

Author

Kriegisch, Martin, Ren, Weijun, Sato-Turtelli, Reiko, Müller, Herbert, Grössinger, Roland, and Zhang, Zhidong

Subjects
Condensed Matter - Materials Science
Abstract

We present magnetostriction and magnetization measurements of a cobalt ferrite Co0.8Fe2.2O4 single crystal. We observe unusual behaviour in the magnetic hard axis of the single crystal which manifests in a jump of the magnetization curve at a critical field. This first order magnetization process (FOMP) which is explained as an anisotropy driven transition is visible at temperatures lower than 150 K. By analyzing the anisotropy constants we found that the higher order anisotropy constant K2 dominates the anisotropy energy. In the magnetostriction measurements the FOMP is clearly visible as a huge jump in the [111] direction, which can be explained by means of a geometric model., Comment: This Paper is already accepted for the conference proceedings of the MMM 2011 (http://www.magnetism.org). The proceedings will be published in April 2012 in Journal of Applied Physics

Published
2011
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2. Magnetic Properties

Author

Wecker, Joachim, Bayreuther, Günther, Ross, Gunnar, Grössinger, Roland, Czichos, Horst, editor, Saito, Tetsuya, editor, and Smith, Leslie, editor

Published
2011
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7. Magnetoelectric properties of Co[Fe.sub.2][O.sub.4]-BaTi[O.sub.3] core-shell structure composite

Author

Duong, Giap V., Groessinger, Roland, and Turtelli, Reiko Sato

Subjects
Barium compounds -- Magnetic properties, Barium compounds -- Electric properties, Magnetization -- Research, Business, Electronics, Electronics and electrical industries
Abstract

The Co[Fe.sub.2][O.sub.4]-BaTi[O.sub.3] core-shell structure composite has been successfully synthesized by wet chemical method. X-ray characterization showed that the composite consisted of two single phases: Co[Fe.sub.2][O.sub.4] and BaTi[O.sub.3]. The saturation magnetization of the Co[Fe.sub.2][O.sub.4] component in composite was found to be similar to those of the bulk sample. It was observed that the longitudinal and transverse magnetoelectric coefficients of the core-shell structure are 18 times higher than those of the mixed structure. Index Terms--Barium titanate, cobalt ferrite, magnetoelectric effect, multiferroics.

Published
2006

14. Magnetic Properties of Highly Textured Fe85Ga15.

Author

Kriegisch, Martin, Groessinger, Roland, Grijalva, Cristina, Muhammad, Atif, Kneidinger, Friedrich, Mehboob, Nasir, Kubel, Frank, and Turtelli, Reiko Sato

Subjects
*MAGNETIC properties of iron compounds, *METALS, *CRYSTAL texture, *MAGNETOSTRICTION, *X-ray diffraction, *THERMAL properties of metals
Abstract

Hysteresis loops and magnetostriction were measured on ring-shaped Fe85Ga15 samples. The samples were annealed at T=980^\circC for 100 h and cooled from annealing temperature in two different ways: one was slowly cooled in an oven and the other one was quenched in cold water. X-ray diffraction results showed a strong texture in these samples, which is dependent on the cooling process. The anisotropy energy and magnetostriction of the samples were calculated based on these determined textures. These results agree qualitatively with magnetization and magnetostriction experiments and support the thermal history influence on the magnetostriction values. [ABSTRACT FROM AUTHOR]

Published
2014
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15. Magnetoelectric Properties of CoFe2O4-BaTiO3 Core-Shell Structure Composite.

Author

Duong, Giap V., Groessinger, Roland, and Turtelli, Reiko Sato

Subjects
*SPINTRONICS, *BARIUM compounds, *COBALT compounds, *ELECTRICAL engineering materials, *MAGNETIC materials, *MAGNETIZATION, *MAGNETIC fields, *FERRITES
Abstract

The CoFe2O4-BaTiO3 core-shell structure composite has been successfully synthesized by wet chemical method. X-ray characterization showed that the composite consisted of two single phases: CoFe2O4 and BaTiO3. The saturation magnetization of the CoFe2O4 component in composite was found to be similar to those of the bulk sample. It was observed that the longitudinal and transverse magnetoelectric coefficients of the core-shell structure are 18 times higher than those of the mixed structure. [ABSTRACT FROM AUTHOR]

Published
2006
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16. Anisotropy and Microstructure of Rare Earth Permanent Magnet Materials.

Author

TECHNISCHE UNIV VIENNA (AUSTRIA) INST OF APPLIED AND TECHNICAL PHYSICS, Skalicky,Peter, Fidler,Josef, Groessinger,Roland, Kirchmayr,Hans, TECHNISCHE UNIV VIENNA (AUSTRIA) INST OF APPLIED AND TECHNICAL PHYSICS, Skalicky,Peter, Fidler,Josef, Groessinger,Roland, and Kirchmayr,Hans

Abstract

The present report is divided into two parts, the microstructural investigations and the anisotropy measurements of rare earth permanent magnet materials. Section I shows that the hardmagnetic properties, i.e. coercivity, of the individual Nd-Fe-B permanent magnet material strongly depends on the compositional and processing parameters (milling, blending, annealing, etc.) and are directly correlated to the microstructural properties (grain size, composition and distribution of phases, crystal defects and precipitates) and to the magnetocrystalline anisotropy of the material. By means of transmission electron microscopy together with STEM X-ray microanalysis at least three categories of phases wee identified in sintered rare earth-iron permanent magnets. From microstructural investigations it can be assumed that the coercivity of sintered rare earth-iron permanent magnet materials is controlled by the nucleation and expansion fields for reversed domains. In Section II the magnetic anisotropy measurements of various rare earth-iron based magnets between 80 K and the Curie temperature are shown and the results are discussed by means of a expanded model for the anisotropy field. From the study of the temperature dependence of the anisotropy field of the mixed crystal series (N,RE)15Fe77B8 (RE=Y, La, Ce) the One Ion Character of the Nd sublattice is shown.

Published
1986

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