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1

Interlayer Coupling in EuS-Based Superlattices (Dependence on the Energy Structure of Non-Magnetic Layer)

100%

Sankowski P., Kacman P.

Acta Physica Polonica A

|

2003

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vol. 103

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issue 6

621-628

EN

The interlayer coupling between ferromagnetic EuS layers separated by spacer layers of diamagnetic insulators, YbSe and SrS, is studied within a 3D tight-binding model. The dependencies of the coupling strength on the energy structure of the spacer, on strains resulting from the lattice mismatch between the superlattice constituents, as well as on an applied hydrostatic pressure and lattice deformations, are presented. The sign and the range of the obtained coupling agree with the behavior of magnetic correlations observed recently in neutron reflectivity spectra of EuS/YbSe superlattices.

2

Spin-Dependent Phenomena in (Ga,Mn)As Heterostructures

100%

Sankowski P., Kacman P.

Acta Physica Polonica A

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2006

|

vol. 110

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issue 2

139-150

EN

A model for spin-dependent tunneling in semiconductor heterostructures, which combines a multi-orbital empirical tight-binding approach with a Landauer-Büttiker formalism, is presented. Using this approach we explain several phenomena observed in modulated structures of (Ga,Mn)As, i.e., large values of the electron current spin polarization in magnetic Esaki- Zener diode and the high tunneling magnetoresistance ratio. Next, the relevance of this theory to assess the tunneling anisotropic magnetoresistance effect is studied. The results of applying the tight-binding model to describe the recently observed interlayer exchange coupling in (Ga,Mn)As-based superlattices are also shown.

3

Interlayer Coupling in EuS-Based Superlattices Deduced from Neutron Scattering Experiments

61%

Sankowski P., Kępa H., Kacman P., Sipatov A., Majkrzak C., Giebultowicz T.

Acta Physica Polonica A

|

2004

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vol. 105

|

issue 6

607-614

EN

The ferromagnetic/diamagnetic semiconductor superlattices, EuS/PbS and EuS/YbSe, were studied by neutron reflectivity. In order to determine the strength of the interlayer coupling, the intensity of the first magnetic Bragg peak vs. applied external magnetic field was measured. Additionally, the in-plane anisotropy and the domain structure were studied by polarized neutron reflectivity. The dependence of the intensity of the antiferromagnetic neutron reflectivity peak vs. magnetic field was simulated using a Stoner-Wohlfarth model. To reproduce the observed spectra it was necessary to take into account the presence of fluctuations of the nonmagnetic layers thickness, by assuming a Gaussian spread of the interlayer coupling constant $J$. For both EuS/PbS and EuS/YbSe superlattices, the best fit was obtained for the directions of the in-plane easy axes, which agree with those determined by polarized neutron reflectivity.

4

Experimental and Theoretical Analysis οf PbTe-CdTe Solid Solution Grown by Physical Vapour Transport Method

42%

Szot M., Szczerbakow A., Dybko K., Kowalczyk L., Smajek E., Domukhovski V., Łusakowska E., Dziawa P., Mycielski A., Story T., Bukała M., Galicka M., Sankowski P., Buczko R., Kacman P.

Acta Physica Polonica A

|

2009

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vol. 116

|

issue 5

959-961

EN

Bulk monocrystals of Pb_{1-x}Cd_{x}Te, with the Cd content x up to 0.11, were grown by physical vapour transport method. The structural, electrical and optical properties of these ternary crystals were studied experimentally and theoretically. All investigated samples exhibit rock-salt structure and high crystal quality, which was confirmed by X-ray rocking curve width parameter of about 100 arcsec. The decrease of the lattice parameter with increasing Cd content x was found experimentally, in agreement with ab initio calculations. The band structures of Pb_{1-x}Cd_{x}Te mixed crystals for x values up to 0.2 were calculated using tight binding approach. The calculated band gap in the L-point increases with the Cd content in qualitative agreement with photoluminescence measurements in the infrared. For all studied Pb_{1-x}Cd_{x}Te samples, the Hall effect and electrical conductivity measurements, performed in the temperature range from 4 to 300 K, revealed p-type conductivity.

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Interlayer Coupling in EuS-Based Superlattices (Dependence on the Energy Structure of Non-Magnetic Layer)

Spin-Dependent Phenomena in (Ga,Mn)As Heterostructures

Interlayer Coupling in EuS-Based Superlattices Deduced from Neutron Scattering Experiments

Experimental and Theoretical Analysis οf PbTe-CdTe Solid Solution Grown by Physical Vapour Transport Method