arXiv subjects

Trilochan Sahoo

Publications and source records attributed to Trilochan Sahoo.

5 recordsLinked to original sources

arXiv2025

Ferroelectric metal-organic frameworks as wide band gap materials

Wide band gap materials are particularly relevant at high temperatures. The band gap shrinkage at higher temperatures prevents device applications with narrow band gap semiconductors. Considering $\alpha$-phase strontium cyanurate as a prototype structure, we identify a group of metal-organic frameworks (MOFs) that exhibit ultra-wide band gaps ranging from 5.5 to 5.7 eV. Recently, a strontium cyanurate compound was found to undergo a phase transition from a high-symmetry $\beta$-phase to a low-symmetry ferroelectric $\alpha$-phase when the temperature was reduced. In the present study, utilizing group theory techniques, we unravel that a zone-center $\Gamma_2^-$ phonon mode modifies our structures from high-symmetry $\beta$-phase to a low-symmetry $\alpha$-phase for A$_3$(O$_3$C$_3$N$_3$)$_2$ MOFs with A = Mg, Ca, Sr, and Ba. We implement first-principles calculations to investigate structural, ferroelectric, and optical properties of these compounds in $\alpha$-phase. The switching barriers between bistable polar states are also estimated. Further, to realize their feasibility, we examine the dynamical and thermal stabilities for all of these MOFs.

cond-mat.mtrl-sci↗

arXiv2025

Polarization-Magnetization Coupling in Visible Light Ferroelectric Double Perovskites

The bulk photovoltaic effect (BPVE), arising from broken inversion symmetry in ferroelectrics, offers a distinct pathway toward high-efficiency next-generation photovoltaics. We propose and investigate A/A$^\prime$-ordered double perovskites KLaFeMoO$_6$ and NaLaFeMoO$_6$ as promising single-phase ferroelectric photovoltaic (FE-PV) materials. First-principles calculations reveal robust P2$_1$ symmetry with A-site layer and B-site rock-salt ordering, accompanied by hybrid improper ferroelectricity driven by $a^{-}a^{-}c^{+}$ octahedral tilts. Both compounds exhibit significant spontaneous polarization and indirect band gaps of $\sim$ 1.8 eV, well suited for visible-light absorption ($>$10$^5$ cm$^{-1}$). Low carrier effective masses along the polar axis indicate efficient charge transport. \textit{Ab initio} molecular dynamics simulations (AIMD) show that polarization-coupled magnetization switching is feasible above room temperature, making these materials suitable for room-temperature applications.

cond-mat.mtrl-sci↗

arXiv2025

Unveiling Insulating Ferro and Ferrimagnetism in Double-Double Perovskite Oxides

The emergence of ferro- and ferrimagnetic behavior in insulating materials is uncommon, largely due to Hund's rules. Utilizing symmetry analysis, first-principles methods, and classical Monte Carlo simulations, \textcolor{black}{we report technologically important insulating ferro and ferrimagnetic double-double perovskite oxides. Our study predicts LaA$^{\prime}$MnNiO$_6$ (A$^{\prime}$ = V, Cr, Mn, Co, and Ni) as promising candidates for spintronic and optical applications exhibiting band gaps between 1.3 eV and 1.9 eV. We explain the mechanisms driving band gap openings and magnetic exchange interactions in these ferro and ferrimagnetic compounds. Monte Carlo simulations, together with state-of-the-art orbital-decomposed exchange parameter analysis, reveal intriguing variations in magnetic transition temperatures (up to 242 K) and the corresponding exchange mechanisms in all LaA$^{\prime}$MnNiO$_6$ compounds.} In addition, we assess the thermodynamic and dynamic stability of these compounds to comment on the feasibility of these systems.

cond-mat.mtrl-sci↗

arXiv2019

Electronic and Optical Properties of Zinc based Hybrid Organic-Inorganic Compounds for Ultraviolet Applications

Hybrid organic-inorganic (HOI) compounds are excellent candidates for a wide spectrum of applications in diverse fields such as optics, electronics, energy and biotechnology. Their broad range of versatility is achieved by combining the functionalities of organic and inorganic materials to generate unique properties. Current research has mostly focused on perovskite HOIs due to their wide range of uses in solar cells, photo detectors and memory devices. However, drawbacks such as instability and lead toxicity limit further implementation into other new areas. Thus, there is a need to develop stable and non-toxic HOI perovskite materials. Zinc is an attractive substitute for Pb in HOIs. Here, we apply a functionality based materials selection approach to screen for Zn-based HOI compounds from two crystallographic repositories; Inorganic Crystal Structure Database and American Mineralogist Crystal Structure Database. We successfully identify thirteen Zn-based HOI compounds. The electronic structure and optical properties of these compounds are investigated using density functional theory. The calculated optical absorbance fall within the far ultra-violet (FUV) region of 200-112 nm wavelength. We selected four of these compounds and calculated their band gaps; they were found to range between 4.9-5.7 eV. Considering that the UV absorbance is three times larger than average tissue absorbance and the refractive index (> 1.49) is greater than typical tissue materials, one could consider these Zn-based HOI compounds for selective photothermolysis treatment and UV protectant coating for electronic devices.

cond-mat.mtrl-sci↗

arXiv2016

Scattering of oblique waves by permeable vertical flexible membrane wave barriers

The interaction of obliquely incident surface gravity waves with a vertical flexible permeable membrane wave barrier is investigated in the context of three-dimensional linear wave-structure interaction theory. A general formulation for wave interaction with permeable submerged vertical membrane is given. The analytic solution of the physical problem is obtained by using eigenfunction expansion method, and boundary element method has been used to get the numerical solution. In the boundary element method, since the boundary condition on the membrane is not known in advance, membrane motions and velocity potentials are solved simultaneously. From the general formulation of the submerged membrane barrier, the performance of bottom-standing, surface-piercing and fully extended membrane wave barriers are analyzed for various wave and structural parameters. It is found that the efficiency of the submerged, surface-piercing and bottom-standing membrane wave barriers can be enhanced in waves for certain design conditions. From the analysis of various membrane configurations and parameters, it can be concluded that permeable membrane wave barrier can function as a very effective breakwater if it is properly designed.

physics.flu-dyn↗