2 research outputs found
Motional Narrowing Effects in the Excited State Spin Populations of Mn-Doped Hybrid Perovskites
Spināorbit coupling in the electronic states of
solution-processed
hybrid metal halide perovskites forms complex spin-textures in the
band structures and allows for optical manipulation of the excited
state spin-polarizations. Here, we report that motional narrowing
acts on the photoexcited spin-polarization in CH3NH3PbBr3 thin films, which are doped at percentage-level
with Mn2+ ions. Using ultrafast circularly polarized broadband
transient absorption spectroscopy at cryogenic temperatures, we investigate
the spin population dynamics in these doped hybrid perovskites and
find that spin relaxation lifetimes are increased by a factor of 3
compared to those of undoped materials. Using quantitative analysis
of the photoexcitation cooling processes, we reveal increased carrier
scattering rates in the doped perovskites as the fundamental mechanism
driving spin-polarization-maintaining motional narrowing. Our work
reports transition-metal doping as a concept to extend spin lifetimes
of hybrid perovskites
Optically Triggered NeĢel Vector Manipulation of a Metallic Antiferromagnet Mn<sub>2</sub>Au under Strain
The absence of stray fields, their insensitivity to external
magnetic
fields, and ultrafast dynamics make antiferromagnets promising candidates
for active elements in spintronic devices. Here, we demonstrate manipulation
of the NeĢel vector in the metallic collinear antiferromagnet
Mn2Au by combining strain and femtosecond laser excitation.
Applying tensile strain along either of the two in-plane easy axes
and locally exciting the sample by a train of femtosecond pulses,
we align the NeĢel vector along the direction controlled by
the applied strain. The dependence on the laser fluence and strain
suggests the alignment is a result of optically triggered depinning
of 90Ā° domain walls and their motion in the direction of the
free energy gradient, governed by the magneto-elastic coupling. The
resulting, switchable state is stable at room temperature and insensitive
to magnetic fields. Such an approach may provide ways to realize robust
high-density memory device with switching time scales in the picosecond
range