Title: Pattern Formation in Evaporating Polymer Solutions- Interplay between Dewetting and Decomposition

Abstract: Pattern formation during solution evaporation is a complex interplay of multiple processes. In my talk, I will discuss how initial conditions affect pattern formation. We observed re-entrant behaviour of the lateral length scale, characterizing the pattern with initial concentration. Our simulations capture two different length scales, revealing the reasons for the underlying re-entrant behaviour between larger and shorter lengths corresponding to dewetting and phase separation, respectively.

Title: Magnetization reversal of 40 nm Fe3O4 nanoparticle at low temperature

Abstract: The magnetic measurement of a 40 nm single F e3O4 nanoparticle at 2 K will be presented. The particle is placed on the weak link of a µ-SQUID for best coupling. The angle-dependent switching field and M-H plots will be shown. 

Title: Emergence of pseudo-active dynamics in anisotropic diffusion of ellipsoidal Brownian particles

Abstract: Shape asymmetric particles, such as ellipses, show rich dynamical behaviors like anisotropic diffusion and breaking of ergodicity due to coupling between rotational and translational motion. We studied the dynamical properties of ellipsoidal Brownian particles and compared them with those of self-propelled spherical Brownian particles to characterize them as pseudo-active dynamics. Both systems exhibit anisotropic diffusion over a characteristic time scale, called persistent time, which is coupled to the orientational dynamics of the particle. The persistent time governs their long time motions and thereby makes their dynamics comparable over the observation timescale. We corroborated and interpreted our experimental results using Langevin theory and numerical simulations. Our conclusions from the comparison of anisotropic and active diffusion offer insights into fundamental diffusive processes, which may help in understanding transport phenomena in membranes and the motion of anisotropic macromolecules.

Title: Crystalline electric field and large anomalous Hall effect in the candidate topological material CeGaSi

Abstract: We report a comprehensive investigation of CeGaSi single crystals, including magnetic, thermodynamic, electronic, and magnetotransport properties. The powder x-ray diffraction refinement revealed that CeGaSi crystallizes in LaPtSi-type tetragonal structure with space group I41md. The electrical resistivity data show a metallic nature with a sharp drop occurring around Tm ∼ 11 K, revealing a magnetic phase transition, which is confirmed by magnetic susceptibility and heat capacity data. The magnetic susceptibility, magnetization, and heat capacity data are analyzed through the crystalline electric field based point charge model, suggesting that the six degenerate ground states of Ce3+ (J = 5/2) ion split into three doublets with an overall splitting energy ∼ 288 K. The maximum negative magnetoresistance in CeGaSi for both B∥c and B∥ab field-direction is observed near Tm, it is attributed to the suppression of spin-disorder scattering by the magnetic field. The Hall resistivity data for B∥c and B∥ab show anomalous Hall signal. Our scaling analysis suggests that anomalous Hall effect in CeGaSi is dominated by the skew scattering mechanism. In addition, first-principles calculations identify CeGaSi as a nodal-line metal. 

Title: A Comprehensive Study of ALPs from B-decays

Abstract: We study axion-like particles (ALPs) through flavor changing neutral current processes followed by hadronic decays in a generic effective theory framework. We compute the anomalous dimension matrix, taking into account all one-loop and relevant two-loop contributions. We explicitly show that UV and IR divergences cancel. We also compute the decay and branching fractions of the ALP pertaining to our framework. Finally we present current bounds and future projections on ALP parameter space.

Title: How plastoglobules are formed in green algae?

Abstract: Plastoglobules are droplet-like organelles with a hydrophobic core of neutral lipids surrounded by a lipid monolayer, usually found in the chloroplasts of most plants and green algae. They not only serve as lipid storage in the thylakoid membranes but are also involved in many cellular processes, including photoprotection metabolite synthesis, protein recruitment, and chloroplast differentiation. Unlike the lipid droplets, which nucleate, grow, and subsequently detach from the endoplasmic reticulum (ER) membrane, plastoglobules remain permanently coupled to the stromal side of the thylakoid membrane. In this study, we employ molecular dynamics simulations to investigate the growth mechanism of plastoglobules in a model thylakoid membrane. Our findings suggest that significant membrane remodeling, likely driven by the thylakoid membrane proteins, is essential for the directional growth and stability of the plastoglobules.

Title: Planar Hall Effect in Quasi-Two-Dimensional Materials 

Abstract: The planar Hall effect in 3D systems is an effective probe for their Berry curvature, topology, and electronic properties. However, the Berry curvature-induced conventional planar Hall effect is forbidden in 2D systems as the out-of-plane Berry curvature cannot couple to the band velocity of the electrons moving in the 2D plane. Here, we demonstrate a unique 2D planar Hall effect (2DPHE) originating from the hidden planar components of the Berry curvature and orbital magnetic moment in quasi-2D materials. We identify all planar band geometric contributions to 2DPHE and classify their crystalline symmetry restrictions. Using gated bilayer graphene as an example, we show that in addition to capturing the hidden band geometric effects, 2DPHE is also sensitive to the Lifshitz transitions. Our Letter motivates further exploration of hidden planar band geometry-induced 2DPHE and related transport phenomena for innovative applications.

Title: Study of critical behavior and magnetocaloric properties of van der Waals CrGa2Te7

Abstract: Emergent magnetism in van der Waals materials opens a new horizon for a multitude of fundamental phenomena and it facilitates the development of new spintronics and magnetocaloric devices for energy-efficient quantum computation. In this work, we carry out comprehensive study of critical behavior and magnetocaloric effect associated with weak ferromagnetism in layered van der Waal CrGa2Te7 single crystal. We investigate the critical behavior of CrGa2Te7 using different methods, including modified Arrott-plot, Kouvel-Fisher method, and critical isotherm analysis. Computed sets of critical exponents β = 0.381(5), γ = 1.147(5) and δ = 4.01(3) for H ∥ c and β = 0.334(5), γ = 1.032(5) and δ = 4.083(3) for H ∥ ab, are self-consistent and well-obeys the scaling relations. Moreover, renormalization group theory analyses suggest the spin interaction is 3D Heisenberg and 3D Ising type with long range magnetic coupling which decays spatially slower than J(r) ≈ r ^(−4.70) along H ∥ c and J(r) ≈ r ^(−4.56) for H ∥ ab, respectively.

Title: Towards measuring spectral fluctuations via multichannel photon timestamping

Abstract: To study spectral fluctuations in quantum dot photoluminescence, we desinged and implemented an experimental setup based on multichannel photon timestamping measurements. Here, we describe the results of our preliminary measurements. 

Title: Entanglement, $\text{T}\bar{\text{T}}$ and rotating black holes 

Abstract: We investigate the entanglement structure in a $\text{T}\bar{\text{T}}$ deformed holographic CFT$_2$ with a conserved charge. We utilize conformal perturbation theory to compute the leading order correction to the entanglement entropy due to the $\text{T}\bar{\text{T}}$ deformation in the limit of large central charge. We also observe the same result from the bulk perspective using the finite cut-off theory of $\text{T}\bar{\text{T}}$ deformation for small values of the deformation parameter.

Title: Improved reconstruction of century-long solar magnetic field using a comprehensive SFT model

Abstract: In this work we present an advanced Surface Flux Transport (SFT) model designed to realistically simulate the evolution of solar magnetic flux over a century-long period. Given the limitations of ground-based telescopes, which cannot observe the solar poles due to projection and atmospheric constraints, a comprehensive approach is required to model solar flux transport across the entire solar surface. Our model integrates theoretical frameworks with sunspot area and positional data, incorporating observed morphological asymmetries between magnetic polarities to enhance realism. We address observational gaps of the BMR tilt angle data by employing statistical analysis of the part of observed data and also corrected the overcounting issues in the RGO sunspot data. Utilizing sunspot area data and Gaussian magnetic patches to assign magnetic fields, our model effectively reproduces the empirically observed temporal evolution of solar magnetic flux and polar fields. This approach demonstrates a significant improvement in the accuracy and realism of long-term solar magnetic flux simulations.

Title: Plasmonic patterned surfaces for photonic sensing

Abstract: Photonic sensing gets boosted due to larger light-matter interaction at subwavelength scales present in plasmonic patterned surfaces. The principle is based on the surface plasmon polariton induced at the interface between the modulated surface profile of a dielectric layer and a nanometer-thick metallic layer above it. Our work uses plasmonic surfaces of different surface profiles, made using soft lithography and coated with a thin gold layer, to explore their suitability in biosensing. 

Title: Coupling of Magnetic Nanostructure with Micro-SQUID and Slow spin dynamics in YIG on GGG Substrate

Abstract: Yttrium Iron Garnet (YIG), i.e. Y3Fe5O12, is a ferrimagnetic insulator with significant application potential in spintronics and magneto-optical devices. In this study, we investigate three 40 nm-thick epitaxial YIG films, each grown on a Gadolinium Gallium Garnet (GGG), i.e. Gd3Ga5O12, substrate with different crystallographic orientations — YIG (100), YIG (110), and YIG (111). Small micron-size portions of the films are positioned near 𝜇-SQUID devices using Focused Ion Beam. The angle resolved magnetization hysteresis loops reveal that the coupling between the YIG and the SQUID device systematically depends on the magnetization anisotropy and the films orientation relative to the SQUID sensor. This is successfully understood and modelled. The low-temperature magnetic properties of YIG (100), particularly the M-H loops measured at 2.5 K show hysteresis with a horizontal shift indicating an unexpected exchange bias. This exchange field seems to arise from a growth-induced interlayer at the YIG and GGG interface, which is confirmed by TEM imaging. The interlayer arises from the iron diffusion into GGG, and its natural ground state appears to be spin disordered. The interlayer exhibits an exchange coupling with the YIG film, with a spin freezing temperature (Tf) of around 6 K. The magnetic orientation of this interlayer could be manipulated by different direction field-cooling from above Tf. The spin-disordered nature of the interlayer imposes multiple metastable states and lead to a slow spin dynamic in the system with the low temperature state being very sensitive to the precise field cooling temperature TFC and the waiting time, tw. The variation of the Hex field with tw reveals that the metastable interlayer undergoes continuous spin rearrangement and relaxation involving different timescales. As the waiting time increases, the system gradually settles towards a zero-exchange field. The inherent disorder in the system allowed us to regulate the exchange field at 2.5 K, enabling its manipulation between its maximum value and zero. This demonstrates a kinetic control of the exchange bias in YIG films on GGG.

Title: Gluon gravtiational form factors and mechanical properties of nucleons

Abstract: Nucleons, the fundamental constituents of atomic nuclei, are composed of quarks and gluons and exhibit a complex internal structure described by partonic degrees of freedom. In this talk, I will present recent results on proton gluon gravitational form factors (GFFs) obtained using the light-front spectator model. These GFFs, derived from the matrix elements of the energy-momentum tensor, provide insights into the spatial distributions of mass, angular momentum, and mechanical properties.

Title: Tunable Topological Phases in Quantum Kirigamis

Abstract: Advances in engineering mesoscopic quantum devices have led to new material platforms where electronic transport can be achieved on foldable structures. In this respect, we study quantum phases and their transitions on a Kirigami structure, a Japanese craft form, where its individual building blocks are topologically non-trivial. In particular, we find that by mechanically deforming the Kirigami structure one can engineer topological phase transitions in the system. Using a multipronged approach, we show that the physics of the system can be captured within a transfer matrix formalism akin to Chalker-Coddington networks, where the junctions describe scattering between effective non-Hermitian one-dimensional edge channels. We further show that the nature of the Kirigami structure can affect the critical folding angles where the topological phase transitions occur. Our study shows the rich interplay between topological quantum phenomena and structural configuration of an underlying Kirigami network reflecting its potential as an intriguing platform.

Title: Universality and relaxation in three-dimensional electron magnetohydrodynamic turbulence

Abstract: We study universal energy cascade in 3D incompressible electron magnetohydrodynamics (EMHD) turbulence. Using two-point statistics, we derive exact scaling relations for scale-to-scale transfer of total energy. The derived exact relations are verified using data from direct numerical simulations of EMHD system. A Kolmogorov-type universal cascade regime is found where a scale-independent transfer of energy is observed. By removing the driving, we subsequently study the corresponding turbulent relaxation. Principle of vanishing nonlinear transfers is employed to theoretically obtain the relaxed conditions which are verified numerically. 

Title: Hydrodynamics in the Carrollian regime

Abstract: Carroll hydrodynamics arises in the c→0 limit of relativistic hydrodynamics. Instances of its relevance include the Bjorken and Gubser flow models of heavy-ion collisions, where the ultrarelativistic nature of the flow makes the physics effectively Carrollian. In this paper, we explore the structure of hydrodynamics in what can be termed as the Carrollian regime, where instead of keeping only the leading terms in the c→0 limit of relativistic hydrodynamics, we perform a small-c expansion and retain the subleading terms as well. We do so both for perfect fluids as well as viscous fluids incorporating first order derivative corrections. As apposite applications of the formalism, we utilize the subleading terms to compute modifications to the Bjorken and Gubser flow equations which bring in, in particular, dependence on rapidity.

Title: Time-reversal symmetry breaking superconductivity in HfRhGe: a noncentrosymmetric Weyl semimetal

Abstract: Weyl semimetals are a novel class of topological materials with unique electronic structures and distinct quantum properties. Among them, HfRhGe stands out as a noncentrosymmetric Weyl semimetal exhibiting unconventional superconductivity. Using muon-spin rotation and relaxation (μSR) spectroscopy combined with thermodynamic measurements, we identify a fully gapped superconducting state in HfRhGe that breaks time-reversal symmetry at the superconducting transition. This symmetry breaking could induce a topological phase transition, as time-reversal symmetry is essential for protecting the normal-state Weyl topology, as confirmed by comprehensive first-principles calculations. Furthermore, Ginzburg-Landau analysis suggests that an unconventional loop supercurrent superconducting state emerges in HfRhGe. The presence of multiple Weyl points near the Fermi level, along with surface Fermi arcs spanning the Fermi level, further establishes HfRhGe as a promising platform for exploring topological superconductivity.

Title: Fragmentation dynamics of 〖SO〗_2^(2+)in collision with energetic protons

Abstract: Molecular fragmentation following ionization in ion-molecule collision is an important technique for laboratory investigation of collision-induced chemistry occurring in space and planetary environments. During ionization, the geometry of the molecule itself may change, opening up hitherto unavailable channels of fragmentation. In some cases, the molecular ion may undergo isomerisation. 〖SO〗_2 gas is an important constituent of terrestrial atmosphere as well has been found in the atmospheric composition of other planetary bodies. It may also play an important role in O2 production in the absence of CO2. We have studied fragmentation dynamics of SO2 using Recoil ion momentum spectroscopy (RIMS), which enables reconstruction of momenta of all the fragment ions at the instant of Coulomb break-up. We focus primarily on the two and three body fragmentation of 〖SO〗_2^(2+) molecular ion. In the two body fragmentation, 〖SO〗_2^(2+) -> O_2^+ + S^+ channel occurs via the isomer 〖[OOS]〗^(2+) formed either from the linear or bent 〖OSO〗^(2+) geometry by nuclear rearrangement. The potential energy curve calculations show that a roaming mechanism in the minimum energy pathway (MEP) is responsible for the isomerisation. The three body fragment momenta have been analysed using Dalitz plot and Newton diagram. The 3D momenta and kinetic energy of the undetected neutral fragment are obtained from momentum conservation in the centre of mass frame of the fragmenting molecular ion. For the channel 〖SO〗_2^(2+) -> O^+ + S^+ + O, the molecular ion may fragment into three particles at the same instant called concerted fragmentation or as a two-step process as 〖SO〗_2^(2+) -> 〖SO〗^+ + O -> O^+ + S^+ + O called sequential fragmentation. The two SO bond-lengths may also undergo change resulting in asymmetric geometry manifested in asymmetric momentum sharing of the momentum by the two outgoing oxygen ions. With increase in energy deposited in the system, the fragmentation mechanism evolves from one to another and at high enough deposited energy, the doubly charged system behaves like a triply charged system. I shall present detailed analysis of 〖SO〗_2^(2+) fragmentation and discuss the results with the aid of Dalitz plots and Newton diagram.

Title: Reconstruction of Deep Cyclic Activity in the Sun by Assimilating Observed Magnetograms in a 3D Dynamo Model

Abstract: The solar magnetic cycle is crucial for understanding solar activity and space weather. Two key models for studying it are the Surface Flux Transport (SFT) model and the 3D Babcock-Leighton dynamo model, respectively. The SFT model examines large-scale magnetic field evolution on the Sun’s surface to predict solar cycles. In contrast, the 3D Babcock-Leighton model explores internal processes that drive the solar magnetic cycle, detailing how toroidal and poloidal magnetic fields regenerate through differential rotation and sunspot decay. In our research, we are the first to incorporate daily magnetogram data into the 3D Babcock-Leighton model. We use a modified data assimilation technique akin to the Advective Flux Transport model. This approach allows us to generate cyclic variations in the toroidal field and investigate the role of internal dynamics in the solar magnetic cycle and polar fields. Our findings will be presented in detail.