Wyniki wyszukiwania - BazTech

Ograniczanie wyników

4 Materials Science Poland

4 2006

Znaleziono wyników: 4

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: półprzewodniki ferromagnetyczne

Sortuj według:

Ogranicz wyniki do:

The RKKY coupling in diluted magnetic semiconductors

Werpachowska A.M., Wilamowski Z.

Materials Science Poland

2006

Vol. 24, No. 3

675--681

This paper is an attempt to modify the classic Ruderman-Kittel-Kasuya-Yosida (RKKY) model to allow an analysis of the experimental data of the magnetic resonance measurements. In our calculations, we follow the treatment of the original authors of the RKKY model but include the finite band splitting, ?, as a phenomenological parameter. The RKKY exchange is not anymore of Heisenberg type and an anisotropy induced by the direction of carrier magnetization occurs.

Magnetic properties of (Eu,Gd)Te semiconductor layers

Dziawa P., Osinniy V., Dobrowolski W., Dybko K., Łusakowska E., Taliashvili B., Story T., Smits C.J.P., Swagten H.J.M.

Materials Science Poland

2006

Vol. 24, No. 3

777--781

In (Eu,Gd)Te semiconductor alloys a well known antiferromagnetic semiconductor compound EuTe is transformed into n-type ferromagnetic alloy. This effect is driven by the RKKY interaction via conducting electrons created due to substitution of Gd3+ for Eu2+ ions. It is expected that due to the high degree of electron spin polarization (Eu,Gd)Te can be exploited in new semiconductor spintronic heterostructures as a model injector of spin-polarized carriers. The (Eu,Gd)Te monocrystalline layers with Gd content up to 5 at. % were grown by MBE on BaF2 (111) substrates with either PbTe or EuTe buffer layers. The measurements of magnetic susceptibility and magnetization revealed that the ferromagnetic transition with the Curie temperature TC=11- 15 K is observed in (Eu,Gd)Te layers with n-type metallic conductivity. An analysis of the magnetization of (Eu,Gd)Te was carried out in a broad range of magnetic fields applied along various crystal directions both in- and out-of layer plane. It revealed, in particular, that a rapid low field ferromagnetic response of (Eu,Gd)Te layer is followed by a paramagnetic-like further increase towards the full saturatio

In-plane uniaxial anisotropy rotations in (Ga,Mn)As thin films

Sawicki M., Wang K.-Y., Edmonds K.W., Campion R.P., Staddon C.R., Farley N.R.S., Foxon C.T., Dietl T., Gallagher B.L.

Materials Science Poland

2006

Vol. 24, No. 3

627--631

Using SQUID magnetometry we find that in (Ga,Mn)As films the in-plane uniaxial magnetic easy axis is consistently associated with particular crystallographic directions. It can be rotated from the [-110] direction to the [110] direction by low temperature annealing and we show that this change is hole density related. We demonstrate that the magnitude of uniaxial anisotropy as well its dependence on the hole-concentration and temperature can be explained in terms of the p-d Zener model of the ferromagnetism assuming a small trigonal-like distortion.

How to make GaMnAs with high ferromagnetic phase transition temperature?

Sadowski J., Domagała J. Z., Kanski J., Rodriguez C. H., Terki F., Charar S., Maude D.

Materials Science Poland

2006

Vol. 24, No. 3

617--625

We analyze the role of structural defects in GaMnAs and demonstrate how their density can be drastically reduced by in situ post-growth annealing under As capping. Modifications of the magnetic, transport and structural properties of the annealed GaMnAs layers are presented. The main result is that the Curie temperatures are strongly increased relative those of the as-grown layers, from typically 70 - 80 K to 150 - 160 K. The annealed layers exhibit well-ordered smooth surfaces, suitable for further epitaxial overgrowth.