arXiv subjects

Debidutta Pradhan

Publications and source records attributed to Debidutta Pradhan.

3 recordsLinked to original sources

arXiv2026

Optoelectronics and Magnetic properties calculation of RE$_2$MnNiO$_6$ (RE=La-Lu,Y) using Density Functional Theory

RE$_2$MnNiO$_6$ (RE = La-Lu) family of ordered double-perovskite oxides hosts a corner-sharing network of alternating NiO$_6$ and MnO$_6$ octahedra whose electronic and magnetic ground states are systematically governed by the A-site ionic radius through the lanthanide contraction. The strong localisation of RE 4f electrons poses a fundamental challenge to density-functional treatments, yet the hybridisation between 4f and neighbouring 5d (RE) or 3d (Ni, Mn) states is central to the origin of exchange interactions and optoelectronic response across the series. We present a comprehensive first-principles study of the electronic structure, lattice dynamics, and optical properties of representative RE2NiMnO6 compounds within the DFT+U framework. To disentangle the role of Kondo-type 4f-d hybridisation, calculations are performed with the RE 4f electrons treated both as frozen core states and explicitly in the valence manifold, enabling a direct assessment of their contribution to the band structure, dielectric function, and phonon dispersion. Spin-polarised calculations reveal significant spin-channel asymmetry, with magnetic moments reaching up to 30 $\mu$B per formula unit for select members of the series. The results establish a unified picture of how 4f occupancy and octahedral distortion collectively determine the magnetic and optoelectronic potential of this double-perovskite family.

cond-mat.mtrl-sci↗

arXiv2025

Structural, electronic, vibrational, optical, piezoelectric, thermal and thermoelectric properties of BCZT from first-principles calculations

Perovskite material such as BCZT (Ba$_{0.875}$Ca$_{0.125}$(Zr$_{0.125}$Ti$_{0.875}$)O$_{3}$) is well known for its high value of piezoceramic properties and Curie temperature which has potential applications in sensors, actuators, optoelectronic and thermoelectric devices. Based on its composition and physical parameters such as pressure and temperature, experimentally, BCZT shows different crystal structures (rhombohedral, tetragonal and orthorhombic) with multiferroic properties. Here, we have designed these materials by comparing experimental stoichiometry and evaluated their stability by calculating the tolerance factor, formation energy, and cohesive energy. The structural, electronic and vibrational properties of BCZT are explored using generalized gradient approximation (GGA) within the framework of density functional theory. We have also shown variation of piezoelectric and optical properties through multiple phases using time dependent density functional theory. The electronic band gap, optical response in the visible light range, as well as piezoelectric, electrical, thermal, and thermoelectric properties, demonstrate excellent characteristics, making this material a promising lead-free ferroelectric candidate for various energy harvesting applications. Boltzmann transport theory is used for the calculation of Seebeck coefficient, electron thermal conductivity, and electrical conductivity to estimate the power factor and figure of merit which represents the efficiency of the material. The high values at the Fermi level suggest that these materials are well-suited for future device applications.

cond-mat.mtrl-sci↗

arXiv2025

Unraveling the electronic, vibrational, thermodynamic, optical and piezoelectric properties of LiNbO$_3$, LiTaO$_3$ and Li$_2$NbTaO$_6$ from first-principles calculations

We have investigated the electronic, vibrational, optical, thermal and piezoelectric properties of LiNbO$_3$, LiTaO$_3$ and Li$_2$NbTaO$_6$ using the first-principles calculation based on the density functional theory. It also shows structural phase transition below $T_c$ due to ionic displacement that may alter the properties of material. We have checked the structural stability by calculating the tolerance factor and formation energy before proceeding to the further calculations. The ground state electronic band structures and corresponding density of states show its semiconducting nature with a band gap range of 3.5-3.7 eV. Optical properties such as dielectric function, absorption coefficient, optical conductivity, refractive index, absorbance and reflectance are calculated using time-dependent density functional theory. Furthermore, the piezoelectric properties and Born effective charges were analyzed to find the correlation between them. In these materials, the distortion induced by the small ionic radius of Li$^{+}$ coupled with strong covalent interaction between transition metal and oxygen leads to high spontaneous polarization which can enhance both piezoelectric and optical properties.

cond-mat.mtrl-sci↗