3 research outputs found
Optical control of in-plane domain configuration and domain wall motion in ferroelectric and ferroelastic
The sensitivity of ferroelectric domain walls to external stimuli makes them
functional entities in nanoelectronic devices. Specifically, optically driven
domain reconfiguration with in-plane polarization is advantageous and thus
highly sought. Here, we show the existence of in-plane polarized sub-domains
imitating a single domain state and reversible optical control of its domain
wall movement in a single-crystal of ferroelectric BaTiO3. Similar optical
control in the domain configuration of non-polar ferroelastic material
indicates long-range ferroelectric polarization is not essential for the
optical control of domain wall movement. Instead, flexoelectricity is found to
be an essential ingredient for the optical control of the domain configuration
and hence, ferroelastic materials would be another possible candidate for
nanoelectronic device applications
Proximitized spin-phonon coupling in topological insulator due to two-dimensional antiferromagnet
Induced magnetic order in a topological insulator (TI) can be realized either
by depositing magnetic adatoms on the surface of a TI or engineering the
interface with epitaxial thin film or stacked assembly of two-dimensional (2D)
van der Waals (vdW) materials. Herein, we report the observation of spin-phonon
coupling in the otherwise non-magnetic TI BiTe, due
to the proximity of FePS (an antiferromagnet (AFM),
120 K), in a vdW heterostructure framework. Temperature-dependent Raman
spectroscopic studies reveal deviation from the usual phonon anharmonicity
at/below 60 K in the peak position (self-energy) and linewidth (lifetime) of
the characteristic phonon modes of BiTe (106 cm and 138
cm) in the stacked heterostructure. The Ginzburg-Landau (GL) formalism,
where the respective phonon frequencies of BiTe couple to phonons
of similar frequencies of FePS in the AFM phase, has been adopted to
understand the origin of the hybrid magneto-elastic modes. At the same time,
the reduction of characteristic of FePS from 120 K in
isolated flakes to 65 K in the heterostructure, possibly due to the interfacial
strain, which leads to smaller Fe-S-Fe bond angles as corroborated by
computational studies using density functional theory (DFT). Besides, our data
suggest a double softening of phonon modes of BiTe
(at 30 K and 60 K), which in turn, demonstrates Raman scattering as a possible
probe for delineating the magnetic ordering in bulk and surface of a hybrid
topological insulator