Room temperature ferromagnetic-like behavior in Mn-implanted and post-annealed InAs layers deposited by Molecular Beam Epitaxy

We report on the magnetic and structural properties of Ar and Mn implanted InAs epitaxial films grown on GaAs (100) by Molecular Beam Epitaxy (MBE) and the effect of Rapid Thermal Annealing (RTA) for 30 seconds at 750C. Channeling Particle Induced X- ray Emission (PIXE) experiments reveal that after Mn implantation almost all Mn atoms are subsbtitutional in the In-site of the InAs lattice, like in a diluted magnetic semiconductor (DMS). All of these samples show diamagnetic behavior. But, after RTA treatment the Mn-InAs films exhibit room-temperature magnetism. According to PIXE measurements the Mn atoms are no longer substitutional. When the same set of experiments were performed with As as implantation ion all of the layers present diamagnetism without exception. This indicates that the appearance of room-temperature ferromagnetic-like behavior in the Mn-InAs-RTA layer is not related to lattice disorder produce during implantation, but to a Mn reaction produced after a short thermal treatment. X-ray diffraction patterns (XRD) and Rutherford Back Scattering (RBS) measurements evidence the segregation of an oxygen deficient-MnO2 phase (nominally MnO1.94) in the Mn-InAs-RTA epitaxial layers which might be on the origin of room temperature ferromagnetic-like response observed.Comment: 16 pages, 5 figures. Acepted in J. Appl. Phy

A content and comparative analysis of strategic management research in the Baltic area

Purpose – The purpose of this paper is to provide a research agenda for qualitative studies in the field of strategic management (SM) in the Baltic area. Design/methodology/approach – A total of 167 SM-related articles in this area between 2000 and 2013 were found. The content within title, abstract and authors’ keywords was analysed by means of a multiple correspondence analysis based on the HOMALS technique. Findings – The intellectual structure of SM in the Baltic area is to some extent similar to the global structure of the field. Hence research on this topic in the Baltic area is well integrated in the field. Three topics of interest have been identified while the fourth seems to offer more limited opportunities for qualitative studies. These are: entry and competition; strategic behaviour and the micro-foundations of strategy; the growth-performance relationship; and global strategies. Research limitations/implications – Despite the modest number of articles in our sample, the findings are consistent with past research on the structure of the SM field. The classification of articles into qualitative- and quantitative-based methods helped provide a research agenda. Practical implications – SM scholars in the Baltic area may find this paper as an interesting input to their quest for finding and justifying their own research path. Originality/value – This is an original literature review. The use of a quantitative method in the literature review and the suggested matrix is a second original contribution to evolving methodologies for content analysis. The method allows the inclusion of large samples while limiting the use of scholars’ intuition. </jats:sec

InAs/InP single quantum wire formation and emission at 1.5 microns

Isolated InAs/InP self-assembled quantum wires have been grown using in situ accumulated stress measurements to adjust the optimal InAs thickness. Atomic force microscopy imaging shows highly asymmetric nanostructures with average length exceeding more than ten times their width. High resolution optical investigation of as-grown samples reveals strong photoluminescence from individual quantum wires at 1.5 microns. Additional sharp features are related to monolayer fluctuations of the two dimensional InAs layer present during the early stages of the quantum wire self-assembling process.Comment: 4 pages and 3 figures submitted to Applied Physics Letter

1-D Cluster Array at the Three Phase Contact Line in Diluted Colloids Subjected to A.C. Electric Fields

Colloidal particles provide an efficient mean of building multiple scale structured materials from colloidal dispersions. In this Brief Report, we account for experimental evidence on the formation of a colloidal cluster array at a three-phase contact line. We study the influence of low frequency external alternating electric fields on a diluted colloidal dispersion opened to the air. We focus on the cluster formation and their evolution in the meniscus by measuring characteristic times and lengths. We observe that the clusters are separated by a well-defined length and that, in our experimental conditions, they survive between five a fifteen minutes. These new results could be of technological relevance in building tailored colloidal structures in non-patterned substrates.Comment: There is supplementary information (see refs. 24, 27), which is available upon request ([email protected]

Quaternary glacial evolution in the Central Cantabrian Mountains (Northern Spain)

Peer reviewedPostprin