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1

Lattice Misfit Strain as Origin for Biquadratic Interlayer Coupling

100%

Jaroszewicz R., Bąk Z., Gruhn W.

Acta Physica Polonica A

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1996

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vol. 89

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issue 3

421-424

EN

The direct observations of some MBE grown superlattices show large interfacial undulations, which is attributed to the elastic relaxation of tensile layers. Assuming that the interface lateral lattice deformation, due to ionic radii misfit, is given by the periodic solution of the Frenkel-Kontorova model, we calculate the magnetoelastic contribution to the biquadratic magnetic coupling between ferromagnetic layers across the nonmagnetic spacer. We show that due to the correlated modulations of the effective bilinear exchange integral, there arises a biquadratic exchange which favours perpendicular orientations of magnetization in adjacent ferromagnetic layers.

2

RKKY-like Biquadratic Exchange in Magnetic Superlattices

100%

Gruhn W., Bąk Z., Jaroszewicz R.

Acta Physica Polonica A

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1996

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vol. 89

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issue 3

417-420

EN

We show that in magnetic metallic superlattices along with the bilinear RKKY-reminiscent interaction between magnetic superlattices there can be an important quadrupole-quadrupole coupling. In an analytical way we derive the range functions of the quadrupol-quadrupole interaction and discuss its relation to magnetoresistivity.

3

Helical Spin Structures in c-Axis Dy/Y Superlattice

100%

Seroczyńska M., Kociński J.

Acta Physica Polonica A

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1996

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vol. 89

|

issue 1

99-104

EN

On the basis of Landau's theory of symmetry changes at continuous phase transitions, we have derived the formulae for two incommensurate helical spin structures which are symmetry allowed in Dy/Y superlattice, when the helical axis is parallel to the c-axis of the hexagonal lattice. These structures have different extinction coefficients in their cross-sections for magnetic scattering of neutrons and therefore can be distinguished by experiment. Magnetic satellite peaks around the reciprocal lattice points K + 0 are allowed for only one of these spin structures, namely that inferred from earlier experiments.

4

Magnetism in Rare-Earth-Transition Metal Systems. Magnetization Reversal and Ultra-High Susceptibility in Sandwiched Thin Films Based on Rare-earth and Cobalt Alloys

80%

Baczewski L., Givord D., Alameda J., Dieny B., Nozieres J., Rebouillat J., Prejean J.

Acta Physica Polonica A

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1993

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vol. 83

|

issue 5

629-641

EN

This paper is composed of two parts: theoretical and experimental. The theoretical part is divided into several sections. The main characteristic properties of 3d (transition metals) and 4f (rare-earth metals) magnetism are explained in the second section. The properties of rare-earth-transition metal compounds are discussed in the third section, particularly with respect to applications. The fourth section is devoted to the rapidly growing field of magnetic thin films. Specifrc properties of ultra-thin films and multilayers are summarized. In the experimental part the original magnetic properties of sandwich films, consisting of a soft amorphous Co-Zr layer placed between two Sm-Co layers with different coercivities, are reported.

5

Annealing Effect of Equiatomic Co/Pt Alloy Films

80%

Gontarz R., Luciński T., Uba L., Uba S., Kudryavtsev Y.

Acta Physica Polonica A

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1994

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vol. 85

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issue 2

427-431

EN

Polycrystalline as-sputtered CoPt alloy films near the equiatomic composition were characterized as consisting of a disordered fcc phase with preferred texture along [111] orientation perpendicular to the film plane. The film annealing at 600°C/16 h induces the disorder-order phase transition confirmed by X-ray diffraction. As a result of the transition an appearance of the ordered tetragonal (fct) phase of AuCuI type with c/a = 0.974 is observed. The c-axis is the easy axis of magnetization. Both longitudinal and polar Kerr hysteresis loops reveal a dramatic increase in the coercivity from 0.1 to 4.5 kOe in annealed CoPt alloy films due to ordering.

6

Diluted Magnetic Semiconductors in High Magnetic Fields

80%

Shapira Y.

Acta Physica Polonica A

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1995

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vol. 87

|

issue 1

107-117

EN

Magnetization studies of diluted magnetic semiconductors in high fields are reviewed. Magnetization steps due to pairs were originally used to measure the near neighbor exchange constant J_{1}. They are now also used to determine: (1) the smaller exchange constants J_{2} and J_{3}, (2) the difference between J_{1}'s for inequivalent near neighbors in wurtzite diluted magnetic semiconductors, and (3) the Dzyaloshinski-Moriya interaction. A different type of magnetization step, due to isolated ions, is used to determine the uniaxial anisotropy of Co^{++} ions in wurtzite diluted magnetic semiconductors. In Fe-based diluted magnetic semiconductors the high-field magnetization exhibits two effects: (1) strong dependence on field direction in cubic diluted magnetic semiconductors, and (2) reversal of the uniaxial magnetization-anisotropy in wurtzite diluted magnetic semiconductors. In (100) EuTe/PbTe superlattices the antiferromagnetic transition, both at zero and finite H, is depressed when the EuTe layer becomes only a few monolayers thick. The easy directions are in the (100) plane of the layer, which is explained by the dipole-dipole anisotropy.

7

Ferromagnetic Behavior of a Short Period Antiferromagnetic Superlattice

80%

Wilamowski Ż., Jantsch W., Faschinger W.

Acta Physica Polonica A

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1995

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vol. 87

|

issue 1

185-188

EN

We present a study of short period MnTe/CdTe superlattices by magnetic resonance. The usually antiferromagnetic structure exhibits critical line broadening above the Néel temperature typical of antiferromagnetic ordering, but also some ferromagnetic properties at lower temperature. We suggest that the observed ferromagnetic-like moment originates from coupling of the moments of the recently proposed strong magnetic polarons.

8

Perturbed Angular Correlation Study of Fe/Cr (1 0 0) and Fe/Co (1 -1 0) Multilayers

80%

Meersschaut J., Swinnen B., Dekoster J., Rots M.

Acta Physica Polonica A

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1997

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vol. 91

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issue 1

217-220

EN

Recently we completed the very first and detailed perturbed angular correlation investigation on MBE-grown very thin film multilayers. The present paper aims to show that otherwise rather unaccessible but unique information on the (interface) magnetism could be obtained. For the Fe/Cr(1 0 0) multilayer system we observe, below a critical Cr thickness of 5.0 nm, a collapse of the spin-density-wave ordering in chromium. While the magnetization in the Fe-layer is in-plane, the Cr magnetization in thicker layers is out-of-plane. In the Fe/Co (1 -1 0) system, the observation of transferred magnetic hyperfine field satellites and their temperature dependence leads to the determination of an oscillating magnetic moment profile at the Fe/Co interface as well as a structure model for the superlattice.

9

ESR Study of the Magnetic Properties of the CdTe/CdMnTe Multi Quantum Wells

80%

Surma M., Godlewski M., Waag A.

Acta Physica Polonica A

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1993

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vol. 84

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issue 3

543-546

EN

The results of electron spin resonance investigations of bulk Cd_{1-x}Mn_{x}Te and of molecular beam epitaxy grown CdTe/CdMnTe single 2 μm thick layer and multi quantum well with Mn concentrations of about x = 0.10 are compared. The Mn^{2+} electron spin resonance spectrum of the MQW CdTe/CdMnTe shows several features different from those observed in the CdMnTe bulk sample. The Mn^{2+} resonance shows a small anisotropy of position and width with the anisotropy axis normal to the heterointerface. The temperature dependence of the width of the electron spin resonance line is also different from that observed for the bulk and for the thick single layer.

Refine search results

Lattice Misfit Strain as Origin for Biquadratic Interlayer Coupling

RKKY-like Biquadratic Exchange in Magnetic Superlattices

Helical Spin Structures in c-Axis Dy/Y Superlattice

Magnetism in Rare-Earth-Transition Metal Systems. Magnetization Reversal and Ultra-High Susceptibility in Sandwiched Thin Films Based on Rare-earth and Cobalt Alloys

Annealing Effect of Equiatomic Co/Pt Alloy Films

Diluted Magnetic Semiconductors in High Magnetic Fields

Ferromagnetic Behavior of a Short Period Antiferromagnetic Superlattice

Perturbed Angular Correlation Study of Fe/Cr (1 0 0) and Fe/Co (1 -1 0) Multilayers

ESR Study of the Magnetic Properties of the CdTe/CdMnTe Multi Quantum Wells