arXiv subjects

Maeng-Je Seong

Publications and source records attributed to Maeng-Je Seong.

3 recordsLinked to original sources

arXiv2026

Tuning magnetic, lattice, and transport properties in CoNb3S6 via Fe doping

We present a comprehensive investigation of the effects of Fe doping on the lattice dynamics, magnetic ordering, and magneto-transport properties of the intercalated van der Waals antiferromagnets Co1-xFexNb3S6 (x = 0.1 and 0.3). Temperature- and polarization-dependent Raman scattering measurements reveal a pronounced blue shift of the 180 cm-1 phonon mode with increasing Fe concentration, indicating enhanced sensitivity of lattice vibrations to Fe-induced structural and mass effects. While the temperature evolution of the phonon modes is dominated by conventional anharmonic phonon softening, subtle anomalies observed near the Néel temperature for x = 0.1 point to weak spin-phonon coupling. Electrical transport and magnetic susceptibility data show clear signatures of the antiferromagnetic phase transitions at TN ~ 20.5-23.7 K for x = 0.1 and TN ~ 32.0 K for x = 0.3. Out-of-plane magnetization measurements reveal hysteretic behavior with two field-induced transitions for x =0.1, which evolve into a single hysteresis loop at x =0.3, signaling a subtle reconstruction of the magnetic ground state. Magneto-transport measurements for x = 0.1 further display a butterfly-shaped hysteretic magnetoresistance and a weak topological Hall effect; however, both features are strongly suppressed at x = 0.3. These results illustrate the critical role of Fe-induced magnetic structure reconstruction in fine-tuning topological and magnetic transport phenomena in intercalated van der Waals antiferromagnets.

cond-mat.mtrl-sci↗

arXiv2025

Manipulation of anisotropic Zhang-Rice exciton in van der Waals antiferromagnets NiPS3-xSex by anion substitution

Spin-entangled excitons have emerged as intriguing quasi-particle excitations in van der Waals magnets. Among them, the recently observed Zhang-Rice (ZR) exciton in NiPS3 has garnered significant research interest due to its strong correlation with magnetic ordering and its exceptionally long-lived coherence. Herein, we present our in-depth temperature- and polarization-dependent photoluminescence (PL) study of anion-substituted NiPS3-xSex (x=0.008,0.03,0.06 and 0.09 ) to explore the nature and dynamics of the ZR exciton. Our results reveal that, similar to the cation substitution, a small percentage of anion substitution effectively destroys and modulates the ZR exciton, as evidenced by the emergence of a weaker, lower-energy PL peak in addition to the primary ZR peak. The primary and secondary PL peaks exhibit the same anisotropic polarization but differ in their peak energy shift and intensity evolution with Se substitution, suggesting varying charge transfers of p-orbitals. Notably, the ZR exciton undergoes rapid thermal destabilization at much lower temperatures than two-magnon excitations, highlighting that p-orbital inhomogeneity beyond the magnetic ordering structure is a decisive factor in driving its thermal quenching.

cond-mat.mtrl-sci↗

arXiv2024

Interplay between magnetic and lattice excitations and emergent multiple phase transitions in MnPSe3-xSx

The intricate interplay between spin and lattice degrees of freedom in two-dimensional magnetic materials plays a pivotal role in modifying their magnetic characteristics, engendering hybrid quasiparticles, and implementing functional devices. Herein, we present our comprehensive and in-depth investigations on magnetic and lattice excitations of MnPSe3-xSx (x = 0, 0.5, and 1.5) alloys, utilizing temperature- and polarization-dependent Raman scattering. Our experimental results reveal the occurrence of multiple phase transitions, evidenced by notable changes in phonon self-energy and the appearance or splitting of phonon modes. These emergent phases are tied to the development of long and short-range spin-spin correlations, as well as to spin reorientations or magnetic instabilities. Our analysis of two-magnon excitations as a function of temperature and composition showcases their hybridization with phonons whose degree weakens with increasing x. Moreover, the suppression of spin-dependent phonon intensity in chemically most-disordered MnPSe3-xSx (x = 1.5) suggests that chalcogen substitution offers a control knob of tuning spin and phonon dynamics by modulating concurrently superexchange pathways and a degree of trigonal distortions.

cond-mat.mtrl-sci↗