11 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
Dynamics of Hot QCD Matter -- Current Status and Developments
The discovery and characterization of hot and dense QCD matter, known as
Quark Gluon Plasma (QGP), remains the most international collaborative effort
and synergy between theorists and experimentalists in modern nuclear physics to
date. The experimentalists around the world not only collect an unprecedented
amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider
(RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large
Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these
data to unravel the mystery of this new phase of matter that filled a few
microseconds old universe, just after the Big Bang. In the meantime,
advancements in theoretical works and computing capability extend our wisdom
about the hot-dense QCD matter and its dynamics through mathematical equations.
The exchange of ideas between experimentalists and theoreticians is crucial for
the progress of our knowledge. The motivation of this first conference named
"HOT QCD Matter 2022" is to bring the community together to have a discourse on
this topic. In this article, there are 36 sections discussing various topics in
the field of relativistic heavy-ion collisions and related phenomena that cover
a snapshot of the current experimental observations and theoretical progress.
This article begins with the theoretical overview of relativistic
spin-hydrodynamics in the presence of the external magnetic field, followed by
the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an
overview of experiment results.Comment: Compilation of the contributions (148 pages) as presented in the `Hot
QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized
by IIT Goa & Goa University, Goa, Indi
Magnetism in four-layered Aurivillius BiFeTiO at high pressures
We report the structural and magnetic properties of four-layer Aurivillius compound BiFeTiO (BFTO) at high hydrostatic pressure conditions. The high-pressure x-ray diffraction (XRD) data does not explicitly show structural phase transitions with pressure, however the observed changes in lattice parameters indicate structural modifications at different pressure values. In the initial pressure region values (up to 2.2 GPa), the lattice parameters a- and b- are nearly equal implying a quasi-tetragonal structure, however as the pressure increases a- and b- diverges apart and exhibits complete orthorhombic phase at pressure values of about 8 GPa. Principal component analysis (PCA) of high pressure Raman measurements point out an evident change in the local structure at about 5.5 GPa indicating that the evolution of the local structure under applied pressure seems to not follow crystallographic changes (long range order). Nuclear forward scattering (NFS) measurements reveal the development of magnetic ordering in BFTO at 5K with high pressures. A progressive increase in magnetic order is observed with increase in pressure at 5 K. Further, NFS measurements carried out at constant pressure (6.4 GPa) and different temperatures indicate that the developed magnetism disappears at higher temperatures (20 K). It is attempted to explain these observations in terms of the observed structural parameter variation with pressure