31 research outputs found
Molecular Beam Epitaxy Growth of Transition Metal Dichalcogenide (Mo,Mn)Se on 2D, 3D and polycrystalline substrates
Magnetic doping of 2D materials such as Transition Metal Dichalcogenides is
promising for the enhancement of magneto-optical properties, as it was
previously observed for 3D diluted magnetic semiconductors. To maximize the
effect of magnetic ions, they should be incorporated into the crystal lattice
of 2D material rather than form separated precipitates. This work shows a study
on incorporating magnetic manganese ions into the MoSe monolayers using
molecular beam epitaxy. We test growth on various substrates with very
different properties: polycrystalline SiO on Si, exfoliated 2D hexagonal
Boron Nitride flakes (placed on SiO / Si), monocrystalline sapphire, and
exfoliated graphite (on tantalum foil). Although atomic force microscopy images
indicate the presence of MnSe precipitates, but at the same time, various
techniques reveal effects related to alloying MoSe with Mn: Raman
scattering and photoluminescence measurements show energy shift related to the
presence of Mn, scanning transmission microscopy shows Mn induced partial
transformation of 1H to 1T^\prime phase. Above effects evidence partial
incorporation of Mn into the MoSe layer.Comment: 13 pages, 8 figure
Molecular Beam Epitaxy growth of MoTe on Hexagonal Boron Nitride
Hexagonal boron nitride has already been proven to serve as a decent
substrate for high quality epitaxial growth of several 2D materials, such as
graphene, MoSe, MoS or
WSe. Here, we present for the first time the molecular
beam epitaxy growth of MoTe on atomically smooth
hexagonal boron nitride (hBN) substrate. Occurrence of
MoTe in various crystalline phases such as distorted
octahedral 1T' phase with semimetal properties or hexagonal 2H phase with
semiconducting properties opens a possibility of realisation of crystal-phase
homostructures with tunable properties. Atomic force microscopy studies of
MoTe grown in a single monolayer regime enable us to
determine surface morphology as a function of the growth conditions. The
diffusion constant of MoTe grown on hBN can be altered 5
times by annealing after the growth, reaching about 5 10
cm/s. Raman spectroscopy results suggest a coexistence of both 2H and 1T'
MoTe phases in the studied samples.Comment: 6 pages, 3 figure
Magneto-optical induced supermode switching in quantum fluids of light
The insensitivity of photons towards external magnetic fields forms one of
the hardest barriers against efficient magneto-optical control, aiming at
modulating the polarization state of light. However, there is even scarcer
evidence of magneto-optical effects that can spatially modulate light. Here, we
demonstrate the latter by exploiting strongly coupled states of semimagnetic
matter and light in planar semiconductor microcavities. We nonresonantly excite
two spatially adjacent exciton-polariton condensates which, through inherent
ballistic near field coupling mechanism, spontaneously synchronise into a
dissipative quantum fluidic supermode of definite parity. Applying a magnetic
field along the optical axis, we continuously adjust the light-matter
composition of the condensate exciton-polaritons, inducing a supermode switch
into a higher order mode of opposite parity. Our findings set the ground
towards magnetic spatial modulation of nonlinear light.Comment: 9 pages, 6 figure
Magnetization dynamics down to zero field in dilute (Cd,Mn)Te quantum wells
The evolution of the magnetization in (Cd,Mn)Te quantum wells after a short
pulse of magnetic field was determined from the giant Zeeman shift of
spectroscopic lines. The dynamics in absence of magnetic field was found to be
up to three orders of magnitude faster than that at 1 T. Hyperfine interaction
and strain are mainly responsible for the fast decay. The influence of a hole
gas is clearly visible: at zero field anisotropic holes stabilize the system of
Mn ions, while in a magnetic field of 1 T they are known to speed up the decay
by opening an additional relaxation channel