29,749 research outputs found
Orthosymplectic Jordan superalgebras and the Wedderburn principal theorem (WPT)
An analogue of the Wedderbur principal theorem (WPT) is considered for finite
dimensional Jordan superalgebras A with solvable radical N, such that N^2=0 and
A/N is isomorphic to Josp_n|2m(F), where F is an algebraicallly closed field of
characteristic zero. Let's we prove that the WPT is valid under some
restrictions over the irreducible Josp_n|2m(F)-bimodules contained in N, and it
is shown with counter-examples that these restrictions can not be weakened.Comment: 13 page
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
Recommended from our members
Composite polymer membranes for laserinduced fluorescence thermometry
We demonstrate a modified version of laser-induced fluorescence thermometry (LIFT) for mapping temperature gradients in the vicinity of small photothermal devices. Our approach is based on temperature sensitive fluorescent membranes fabricated with rhodamine B and polydimethylsiloxane (PDMS). Relevant membrane features for LIFT, such as temperature sensitivity, thermal quenching and photobleaching are presented for a range of 25 °C to 90 °C, and their performance is evaluated upon obtaining the temperature gradients produced in the proximity of optical fiber micro-heaters. Our results show that temperature measurements in regions as small as 750 μm x 650 μm, with a temperature resolution of 1 °C, can be readily obtained
Environmental sensitivity of n-i-n and undoped single GaN nanowire photodetectors
In this work, we compare the photodetector performance of single defect-free
undoped and n-in GaN nanowires (NWs). In vacuum, undoped NWs present a
responsivity increment, nonlinearities and persistent photoconductivity effects
(~ 100 s). Their unpinned Fermi level at the m-plane NW sidewalls enhances the
surface states role in the photodetection dynamics. Air adsorbed oxygen
accelerates the carrier dynamics at the price of reducing the photoresponse. In
contrast, in n-i-n NWs, the Fermi level pinning at the contact regions limits
the photoinduced sweep of the surface band bending, and hence reduces the
environment sensitivity and prevents persistent effects even in vacuum
- …