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On Temperature Dependence of Domain Structure in Cobalt

100%

Szmaja W., Polański K., Dolecki K.

Acta Physica Polonica A

1997

vol. 92

issue 2

469-472

The type-I magnetic contrast in a scanning electron microscope is used to study the domain behaviour on the basal planes of cobalt monocrystals of different thicknesses during a heating cycle. Digital image processing is applied to the original scanning electron microscope images for their restoration, enhancement and analysis. The main reasons for the application of digital image processing are: low level of type-I magnetic contrast, particularly used at the higher temperatures, and the complex character of the magnetic domain structure. The changes in both domain structures and type-I magnetic contrast are due to the strong temperature dependence of magnetocrystalline anisotropy energy for the hcp phase of cobalt, which implies the rotation of magnetic easy axis from the c-axis to the basal plane. The temperature of the magnetic phase transition between an open-flux and a closed-flux domain configuration was found to be dependent on the specimen thickness. The changes in domain structure during the heating cycle were reversible under the condition that the specimen was not carried through the hcp-to-fcc phase transition. Otherwise, they were partially or completely irreversible and were caused by crystal imperfections originating from the transition. The paper shows the great advantage of using digital image processing system for data restoration, enhancement and analysis.

Investigation of the Morphological Structure of Thin Cobalt Films by AFM and TEM

88%

Szmaja W., Balcerski J., Kozłowski W., Grobelny J., Cichomski M.

Acta Physica Polonica A

2008

vol. 113

issue 1

171-174

Thin obalt films, 40 nm and 100 nm in thickness, were evaporated at an incidence angle of 45° in a vacuum of about 10^{-5} mbar, simultaneously on unheated glass substrates and NaCl crystals. The magnetic microstructure of these films was investigated in a previous paper. In the present paper, to obtain an insight into relation between the magnetic microstructure and the morphological structure, we studied the latter structure with atomic force microscopy and transmission electron microscopy. For the films 40 nm as well as 100 nm thick, the presence of contribution of the shape anisotropy (related to the geometric alignment of the grains of the film) to the magnetic anisotropy of the film was found. Nevertheless, for the films investigated, we could not detect crystallographic texture.

Influence of Milling and Compaction Processes οn Magnetic Properties of FeCo Powder

64%

Szumiata T., Gzik-Szumiata M., Brzózka K., Gawroński M., Górka B., Kollár P., Olekšáková D., Polański K., Szmaja W.

Acta Physica Polonica A

2009

vol. 115

issue 1

403-405

Magnetic and structural studies were performed on Fe_{50}Co_{50} material. The samples (disk-shaped, diameter: 10 mm, thickness: 2.5 mm) were fabricated by compaction of powder under pressure of 800 MPa for 5 min at temperatures 300-600°C. The powder was obtained by milling of Fe_{50}Co_{50} alloy swarfs in high-energy planetary mill. The milling time varied from 1 h to 40 h. In the course of milling process the mean size of alloy pieces was decreasing from about 0.5 mm to 0.05 mm (scanning electron microscopy), which provided more compact structure after compression. The annealing process during compaction strongly reduces a coercive field of the samples. Parameters of conversion electron Mössbauer spectra are almost the same for all samples, which points to not significant changes of atomic and magnetic order after milling and compacting.

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3 Acta Physica Polonica A

1 2009

1 2008

1 1997

3 Szmaja W.

2 Polański K.

1 Balcerski J.

1 Brzózka K.

1 Cichomski M.

1 Dolecki K.

1 Gawroński M.

1 Grobelny J.

1 Gzik-Szumiata M.

1 Górka B.

1 Kollár P.

1 Kozłowski W.

1 Olekšáková D.

1 Szumiata T.

Search results

On Temperature Dependence of Domain Structure in Cobalt

Investigation of the Morphological Structure of Thin Cobalt Films by AFM and TEM

Influence of Milling and Compaction Processes οn Magnetic Properties of FeCo Powder