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We report on the appearance of magnetic stripes in MnAs/GaAs(100) epilayers at temperatures well below the ferromagnetic transition of the system. The study has been performed by ferromagnetic resonance experiments (FMR) on MnAs epilayers…

X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by…

Magnetic properties of MnAs were studied as a function of temperature with a superconducting interference device (5 K to 350 K), and atomic force microscopy/magnetic force microscopy (20 K to 360 K). Structural and magnetic properties of…

材料科学 · 物理学 2007-05-23 M. Cheon , S. Hegde , S. Wang , M. M. Bishara , G. B. Kim , H. Luo

Nearly 30% increase of the ferromagnetic phase transition temperature has been achieved in strained MnAs nanocrystals embedded in a wurtzite GaAs matrix. Wurtzite GaAs exerts tensile stress on hexagonal MnAs nanocrystals, preventing a…

MnAs has been grown by means of MBE on the GaN(0001)-(1x1) surface. Two options of initiating the crystal growth were applied: (a) a regular MBE procedure (manganese and arsenic were delivered simultaneously) and (b) subsequent deposition…

材料科学 · 物理学 2009-11-13 I. A. Kowalik , B. J. Kowalski , R. J. Iwanowski , K. Kopalko , E. Łusakowska , M. Sawicki

Formation of MnAs quantum dots in a regular ring-like distribution has been found on MBE-grown (GaMn)As surfaces after low-temperature annealing under As capping. The Mn was supplied by out-diffusing Mn interstitials from (GaMn)As. With 5…

材料科学 · 物理学 2007-05-23 J. Sadowski , M. Adell , J. Kanski , L. Ilver , E. Janik , E. Lusakowska , J. Z. Domagala , R. Brucas , M. Hanson

Single-phase Ni0.46Mn0.54As films with strained C1b symmetry have been successfully grown on GaAs (001) substrates by molecular-beam epitaxy. The epitaxial relationship between the film and the substrate has been studied using synchrotron…

材料科学 · 物理学 2019-01-30 J. L. Ma , H. L. Wang , X. M. Zhang , S. Yan , W. S. Yan , J. H. Zhao

Nucleation processes of mixed-phase states are an intrinsic characteristic of first-order phase transitions, typically related to local symmetry breaking. Direct observation of emerging mixed-phase regions in materials showing a first-order…

In the search for phase change materials (PCM) that may rival traditional random access memory, a complete understanding of the amorphous to crystalline phase transition is required. For the well-known Ge2Sb2Te5 (GST) and GeTe (GT)…

材料科学 · 物理学 2015-06-19 James L. Bosse , Ilya Grishin , Bryan D. Huey , Oleg V. Kolosov

The annealing-induced formation of (Mn,Ga)As nanocrystals in (Ga,Mn)As/GaAs superlattices was studied by X-ray diffraction, transmission electron microscopy and magnetometry. The superlattice structures with 50 A thick (Ga,Mn)As layers…

材料科学 · 物理学 2015-06-03 J. Sadowski , J. Z. Domagala , R. Mathieu , A. Kovacs , P. Dluzewski

Temperature evolution of dielectric response, atomic structure, and lattice dynamics in thin film of sodium niobate in the epitaxial NaNbO$_3$/SrRuO$_3$/(001)MgO heterostructure is studied by dielectric measurements, x-ray diffraction, and…

We have studied the electronic structure of hexagonal MnAs, as epitaxial continuous film on GaAs(001) and as nanocrystals embedded in GaAs, by Mn 2p core-level photoemission spectroscopy. Configuration-interaction analyses based on a…

介观与纳米尺度物理 · 物理学 2011-08-05 M. Moreno , J. I. Cerdá , K. H. Ploog , K. Horn

Thin GaMnAs layers grown by molecular beam epitaxy were subjected to low-temperature post growth annealing, with an amorphous arsenic capping layer deposited on the GaMnAs surface directly after the epitaxial growth. It is shown that the…

材料科学 · 物理学 2007-05-23 J. Sadowski , J. Z. Domagala , V. Osinniy , J. Kanski , M. Adell , L. Ilver , C. Hernandez , F. Terki , S. Charar , D. Maude

Mn-doped GaAs thin films were grown at a high substrate temperature of 580 C. During the growth process, the Mn cell temperature was ramped at different rates, resulting in a variety of different Mn concentration depth profile slopes, as…

介观与纳米尺度物理 · 物理学 2015-02-11 P. Xu , D. Qi , M. L. Ackerman , S. D. Barber , P. M. Thibado

Ferromagnetic properties of In1-xMnxAs thin films were investigated. Room temperature ferromagnetic order was observed in nominally single-phase films with x = 0.01-0.10. Magnetization measurements indicated that these In1-xMnxAs samples…

材料科学 · 物理学 2009-11-10 A. J. Blattner , B. W. Wessels

We report a clear correspondence between changes in the Curie temperature and carrier density upon annealing in epitaxially grown (Ga,Mn)As layers with thicknesses in the range between 5 nm and 20 nm. The changes are dependent on the layer…

材料科学 · 物理学 2009-11-07 B. Sorensen , J. Sadowski , R. Mathieu , P. Svedlindh , P. E. Lindelof

MnAs films grown on GaAs (001) exhibit a progressive transition between hexagonal (ferromagnetic) and orthorhombic (paramagnetic) phases at wide temperature range instead of abrupt transition during the first-order phase transition. The…

介观与纳米尺度物理 · 物理学 2009-11-10 R. Magalhaes-Paniago , L. N. Coelho , B. R. A. Neves , H. Westfahl , F. Iikawa , L. Daweritz , C. Spezzani , M. Sacchi

We report on the temperature stability of pseudomorphic GeSn films grown by molecular beam epitaxy on Ge(001) substrates. Both the growth temperature-dependence and the influence of post-growth annealing steps were investigated. In either…

Control of the crystallization process at the microscopic level makes it possible to generate the nanocrystalline samples with the desired structural and morphological properties, that is of great importance for modern industry. In the…

材料科学 · 物理学 2019-03-25 Bulat N. Galimzyanov , Dinar T. Yarullin , Anatolii V. Mokshin

Voids adjacent to both cubic (ZnS-type) and hexagonal (NiAs-type) Mn-rich nanocrystals are characterized using aberration-corrected transmission electron microscopy in annealed Ga0.995Mn0.005As magnetic semiconductor specimen grown by…

材料科学 · 物理学 2015-05-27 A. Kovacs , J. Sadowski , T. Kasama , J. Domagala , R. Mathieu , T. Dietl , 5 , R. E. Dunin-Borkowski
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