arXiv subjects

Sreekant Anil

Publications and source records attributed to Sreekant Anil.

3 recordsLinked to original sources

arXiv2026

Impact of Cu-Mn ratio on Structure and Defects in Layered Multiferroic Cu1-xMn1+ySiTe3

Multiferroic materials exhibit the coexistence of magnetic and ferroelectric order, enabling control of magnetism through electric fields and vice versa. These properties make them attractive for spintronic and memory device applications. Recent studies on Cu1-xMn1+ySiTe3 (0.04 \leq x \leq 0.26; 0.03 \leq y \leq 0.15) have revealed strong magnetoelectric coupling, with variations in Mn-to-Cu concentration leading to variations in optical, electronic, and magnetic responses. Despite these findings, the influence of nanoscale structure and defects on the observed properties remains poorly understood. In this study, we investigate the structure and nanoscale defects in Cu-deficient Cu1-xMn1+ySiTe3 (Cu:Mn ratio <1, i.e., with 0.04 \leq x \leq 0.26 and 0.03 \leq y \leq 0.15) and Cu-rich Cu1+xMn1-ySiTe3 (Cu:Mn ratio >1, i.e., with 0.04 \leq x \leq 0.3 and 0.13 \leq y \leq 0.31) crystals using scanning/transmission electron microscopy and single-crystal X-ray diffraction. Cu-deficient crystals exhibit extensive stacking faults correlated with chemical inhomogeneity between Mn and Cu, along with variations in Te stacking. In contrast, Cu-rich crystals show fewer stacking faults but contain other local structural variations, such as needle-shaped precipitates and loop-like features. These distinct local structural features between Cu-rich and Cu-deficient crystals can be correlated to variations in their observed properties. Complementary density functional theory calculations confirm that the Cu-rich structure is more polar than the Cu-deficient structure. Overall, this study provides a comprehensive understanding of how subtle changes in chemistry influence the nanoscale structure, defect distribution, and functional properties in Cu1-xMn1+ySiTe3, offering guidance for designing multiferroic materials with tailored performance.

cond-mat.mtrl-sci↗

arXiv2026

Defect Control via Cu Enrichment Enhances Multifunctional Properties in the Polar Semiconductor Cu1+xMn1-ySiTe3

Polar materials have recently attracted significant interest due to their rich multifunctional properties. The chalcogenide polar semiconductor Cu1-xMn1+ySiTe3 (Cu-deficient) is an emerging multiferroic system in which electric polarization is coupled to magnetization. However, its macroscopic ferroelectric polarization is strongly suppressed due to the presence of a high density of stacking faults. In this work, we demonstrate that these crystal defects, likely originating from non-stoichiometry, can be substantially reduced by increasing the Cu content. Cu-enriched samples, Cu1+xMn1-ySiTe3, crystallize in a noncentrosymmetric monoclinic structure (space group Pm) as the Cu-deficient counterpart but show a nearly stacking-fault-free phase, which is attributed to the emergence of an interstitial site. Consequently, the Cu-enriched samples show a pronounced enhancement of the second-harmonic generation (SHG) response compared to Cu-deficient compositions. Magnetically, the Cu-enriched crystals retain long-range antiferromagnetic order with a Neel temperature of TN ~ 33 K without a glassy state but manifest a distinct spin-flop transition along the polar b-axis that is absent in the Cu-deficient compositions. Furthermore, the electronic ground state evolves from insulating to doped semiconducting behavior upon Cu enrichment. Together, these results establish this material system as a unique and versatile platform for elucidating the interplay among composition, crystal defects, and multifunctional properties, offering a route to design magnetic polar systems with tunable quantum functionalities.

cond-mat.mtrl-sci↗

arXiv2026

Successful growth of low carrier density $α$-In$_2$Se$_3$ single crystals using Se-flux in a modified Bridgman furnace

Indium selenide (In$_2$Se$_3$) has garnered significant attention for its intriguing properties and applications in batteries, solar cells, photodetectors and ferroelectric devices. However, the controlled synthesis of single phase $α$-In$_2$Se$_3$ remains challenging owing to its complex phase diagram, presence of multiple polymorphs and the high volatility of selenium that induces non-stoichiometry and unintentional carrier doping. For ferroelectric α-In2Se3, minimizing the carrier density is essential because leakage current can obscure polarization switching. Here, we report the growth of $α$-In$_2$Se$_3$ single crystals using a unique approach, the Se-flux assisted modified vertical Bridgman technique combined with liquid encapsulation under high pressure. This approach creates a high-pressure, Se-rich environment that effectively minimizes Se-vaporization. Structural and compositional analysis using X-ray diffraction, transmission electron microscopy and energy-dispersive X-ray spectroscopy confirm the formation of pure $α$-In$_2$Se$_3$ single crystals with 3R stacking. Furthermore, the crystals exhibit remarkably low carrier density of 1.5-3.2 $\times$ 10$^{16}$ cm$^{-3}$ at 300K$-$the lowest reported to date, reflecting a significant suppression of Se-vacancies relative to the conventional Bridgman or melt-grown crystals. Through transport and ARPES measurements on different batches of crystals, we also demonstrate that the amount of Se-flux plays a crucial role in controlling Se-vacancies. Our results thus establish this modified Bridgman method as an effective strategy for synthesizing large $α$-In$_2$Se$_3$ single crystals with reduced intrinsic defects. This technique can be broadly applied to grow other volatile chalcogenides with reduced defects and controlled stoichiometry.

cond-mat.mtrl-sci↗