25 research outputs found
All-wurtzite (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy
Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core-shell
nanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold
catalyst have been investigated.(In,Ga)As core nanowires were grown at high
temperature (500 {\deg}C) whereas (Ga,Mn)As shells were deposited on the
{1-100} side facets of the cores at much lower temperature (220 {\deg}C). High
resolution transmission electron microscopy images and high spectral resolution
Raman scattering data show that both the cores and the shells of the nanowires
have wurtzite crystalline structure. Scanning and transmission electron
microscopy observations show smooth (Ga,Mn)As shells containing 5% of Mn
epitaxially deposited on (In,Ga)As cores containing about 10% of In, without
any misfit dislocations at the core-shell interface. With the In content in the
(In,Ga)As cores larger than 5% the (In,Ga)As lattice parameter is higher than
that of (Ga,Mn)As and the shell is in the tensile strain state. Elaborated
magnetic studies indicate the presence of ferromagnetic coupling in (Ga,Mn)As
shells at the temperatures in excess of 33 K. This coupling is maintained only
in separated mesoscopic volumes resulting in an overall superparamagnetic
behavior which gets blocked below ~17 K.Comment: 37 pages, 8 figure
Wurtzite vs rock-salt MnSe epitaxy: electronic and altermagnetic properties
Newly discovered altermagnets are magnetic materials exhibiting both
compensated magnetic order, similar to antiferromagnets, and simultaneous
non-relativistic spin-splitting of the bands, akin to ferromagnets. This
characteristic arises from the specific symmetry operations that connect the
spin sublattices. In this report, we show with ab initio calculations that the
semiconductive MnSe exhibits altermagnetic spin-splitting in the wurtzite phase
as well as a critical temperature well above room temperature. It is the first
material from such space group identified to possess altermagnetic properties.
Furthermore, we demonstrate experimentally through structural characterization
techniques that it is possible to obtain thin films of both the intriguing
wurtzite phase of MnSe and the more common rock-salt MnSe using molecular beam
epitaxy on GaAs substrates. The choice of buffer layers plays a crucial role in
determining the resulting phase and consequently extends the array of materials
available for the physics of altermagnetism