arXiv subjects

Ju Hyeon Lee

Publications and source records attributed to Ju Hyeon Lee.

3 recordsLinked to original sources

arXiv2026

Direction-selective intertwined charge, orbital, and lattice orders under uniaxial strain in hole-doped manganite: La0.75Ca0.25MnO3

The complex interplay of charge, spin, orbital, and lattice degrees of freedom governs emergent phases in quantum materials, making strain a powerful control parameter. Recent advances in free-standing layer techniques have enabled extreme strains of nearly 8%, opening access to novel and often unexpected electronic and magnetic phases. Here, using a density functional theory approach, we investigate the effect of direction-selective uniaxial strain on the prototypical Jahn-Teller system La1-xCaxMnO3 (x = 0.25). We find that different strain directions stabilize qualitatively distinct structural, charge, and orbital responses, rather than merely different strengths of the same phase. In particular, extreme uniaxial strain selectively induces cooperative Jahn-Teller, breathing-like, and site-selective modulations, thereby enabling previously inaccessible intertwined orders in manganites. These results establish direction-selective uniaxial strain as a powerful and selective route for engineering emergent phases in quantum materials.

cond-mat.str-el↗

arXiv2025

Revisiting LaMnO3: A density functional theory study

Density functional theory (DFT) has been widely applied to a variety of realistic materials but often struggles to explain the properties of correlated systems. The DFT + U method, which introduces a Hubbard U correction to the DFT, has been instrumental in providing the treatment of systems such as transition metal oxide. The methodological details of DFT + U and their specifics on the electronic structures and magnetic properties of the correlated systems remain incompletely understood. In this study, taking the prototypical transition metal oxide system, LaMnO3, as an example, we systematically assess the performance of the two distinct DFT + U methods, spin-polarized DFT (SDFT + U) and spin-un-polarized DFT (CDFT + U). We found that while Coulomb U acts similarly for the two approaches, Hund JH plays a fundamentally different role, particularly in the determination of the magnetic phases. Our investigation shows the active role of Hund JH on the exchange splitting, leading to distinct magnetic ground configurations in the two methods. We further investigate the associated magnetic exchange interactions and compare our results with so-called beyond-DFT methods.

cond-mat.str-el↗

arXiv2016

Effect of rotational-state-dependent molecular alignment on the optical dipole force

The properties of molecule-optical elements such as lenses or prisms based on the interaction of molecules with optical fields depend in a crucial way on the molecular quantum state and its alignment created by the optical field. However, in previous experimental studies, the effects of state-dependent alignment have never been included in estimates of the optical dipole force acting on the molecules while previous theoretical investigations took the state-dependent molecular alignment into account only implicitly. Herein, we consider the effects of molecular alignment explicitly and, to this end, introduce an effective polarizability which takes proper account of molecular alignment and is directly related to the alignment-dependent optical dipole force. We illustrate the significance of including molecular alignment in the optical dipole force by a trajectory study that compares previously used approximations with the present approach. The trajectory simulations were carried out for an ensemble of linear molecules subject to either propagating or standing-wave optical fields for a range of temperatures and laser intensities. The results demonstrate that the alignment-dependent effective polarizability can serve to provide correct estimates of the optical dipole force, on which a state-selection method applicable to nonpolar molecules could be based. We note that an analogous analysis of the forces acting on polar molecules subject to an inhomogeneous static electric field reveals a similarly strong dependence on molecular orientation.

physics.chem-ph↗