Carrier-induced ferromagnetism in Ge0.92Mn0.08Te epilayers with a Curie temperature up to 190 K

Abstract

IV-VI diluted magnetic semiconductor Ge0.92Mn0.08Te epilayers are grown on BaF2 substrates by molecular beam epitaxy. The ferromagnetic behaviors, such as the spontaneous magnetization, the coercive field, and the Curie temperature TC, are altered by the hole concentration p. In the Ge0.92Mn0.08Te layer with high p, strong magnetic anisotropy and the temperature dependence of the magnetization expected for homogeneous ferromagnets are observed, implying that long-range ordering is induced by the holes. The maximum TC reaches 190 K for 1.57×1021 cm−3.

Phase separation and exchange biasing in the ferromagnetic IV-VI semiconductor Ge1−xMnxTe

“…1͑a͒ for T = 150 K. Therefore, we denote this temperature as T C although the magnetization curves do not follow the classical mean field behavior as has been already observed for Ge 1−x Mn x Te by other groups. 4,5 We attribute this behavior to local fluctuations of the Mn content. However, for samples grown at higher growth temperature T S , the remanence M rem at 2 K drastically decreases.…”

“…1,2 Among the so far less explored materials are magnetic IV-VI compounds 6 like Ge 1−x Mn x Te, for which ferromagnetic Curie temperatures T C of Ϸ150 K have been reported for bulk material 3 and up to 190 K for epitaxial layers grown by molecular beam epitaxy ͑MBE͒. 4,5 In Ge 1−x Mn x Te the incorporated Mn 2+ is isoelectronic to Ge and therefore, the carrier concentration can be controlled independently of the Mn content. 7 Moreover, the solubility limit of Mn in the GeTe host lattice is rather large and reaches up to about 60% in single-phase bulk material Ge 1−x Mn x Te.…”

Magnetic anisotropy induced by crystal distortion in Ge1−xMnxTe/PbTe//KCl (001) ferromagnetic semiconductor layers

“…3. During the measurements the samples were rotated by 360° (with the step of 10°) from [001] direction (H=0°, normal to the layer) either to [1][2][3][4][5][6][7][8][9][10] Maxima and minima of the FMR resonant field clearly identify the hard and easy axes of magnetization. In contrast to the expectations based on shape anisotropy mechanism, the easy magnetization axis in Ge0.86Mn0.14Te/PbTe//KCl is not located in the layer plane, but it is close to the layer normal with a broad magnetic anisotropy energy minimum around H=0°.…”

“…Magnetization, anomalous Hall effect and ferromagnetic resonance (FMR) measurements of (0.1-1) micron-thick Ge1-xMnxTe layers deposited on BaF2 (111) substrates [3][4][5][15][16][17][18] with Mn concentration x<0.2 (i.e. possessing the rhombohedral structure) showed magnetization easy axis oriented along the growth direction (perpendicularly to the layer plane).…”

Anomalous Hall Effect in Ge1-x-yPbxMnyTe Composite System

“…Transition metal doped IVVI compounds are a subject in the recent years of a signicant interest due to the presence of the carrier mediated ferromagnetism [1] with the Curie temperature, T C , about 190 K in Ge 0.92 Mn 0.08 Te thin lms [2]. The nanocomposite crystals with clusters of magnetic impurities might lead to a further increase of T C , above 190 K. GePbMnTe mixed crystals create opportunity to control electric and magnetic properties independently [3].…”