Ajit Kumar Jena

Cr1+δTe2, a family among two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenides, has garnered significant interest owing to its tunable structural, electrical, and magnetic properties controlled by the concentration of self-intercalated Cr atoms. Among various external stimuli, pressure provides an additional route to tune the associated physical properties of these materials through modifications of interatomic distances, which can substantially alter the electrical and magnetic properties. In the present study, we report the theoretical and experimental investigation of the pressure-induced structural and electrical properties of Cr1.28Te2 with trigonal (P3̅m1) crystal structure. The pressure-dependent synchrotron X-ray powder diffraction (SXRPD) analysis revealed iso-structural transitions at ∼4.7, ∼9.9, and ∼19.7 GPa, evidenced by the deviation of lattice parameters from linear pressure dependence. The temperature-dependent resistance curves measured over a range of applied pressure show the presence of metal-semiconductor-metal transition near ∼7.8 and ∼16.8 GPa, close to the pressures of the iso-structural transitions. Additionally, a low-temperature resistance minimum observed at low pressures suggests the emergence of localization-related effects. The resistance minimum gradually shifts toward higher temperatures with increasing pressure, indicating the progressive enhancement of localization effect under compression. Further, theoretical calculations suggest that the metallic nature of Cr1.28Te2 below the metal-semiconductor transition (i.e., at low pressure) is dominated by Cr2–3d states, whereas above the transition (at high pressure), the metallicity is governed by Te–3p states. A nonmonotonic evolution of the magnetic state is also observed under pressure, which is likely to originate from modified exchange interactions due to the change in bond lengths under applied pressure. Overall, the combined experimental and theoretical results provide a detailed insight into pressure-induced structural and electrical properties of Cr1.28Te2.

2D materials showing room‐temperature magnetism and high coercivity are highly attractive for combining magnetism with semiconducting functionality in spintronic devices. In this work, the magnetic properties of the 1T phase of MoS ₂ have been studied at room temperature. We observe ferromagnetism with a coercivity of ∼0.3 T and a maximum saturation magnetization of 0.26 emu g ⁻¹ at room temperature. This is the highest among coercivities reported so far in 2D magnets at room temperature. MoS ₂ nanosheets are prepared using a single‐step hydrothermal synthesis with a relative 1T‐phase reaching up to 77%. Structural analysis reveals lattice expansion, reflected by an increased interplanar spacing, which correlates directly with both the relative 1T phase fraction and enhanced coercivity. Our findings demonstrate a direct structural route to engineer coercivity through phase and strain control in MoS ₂ , offering a scalable platform for phase‐engineered magnetism in layered materials.

This study explores the magnetic and electronic properties of 3d transition metal doped phosphorene monolayers using first principles calculations, with a focus on their potential two dimensional (2D) spintronics applications. We identify Ti, V, Cr, Mn and Fe doping induces magnetism in otherwise non-magnetic phosphorene with respective magnetic moment of 1μB, 2μB, 3μB, 4μB and 3μB per dopant. The induced magnetic moment is attributed to the intra-atomic charge transfer (from 4s to 3d) and subsequent spin-dependent electronic redistribution at the dopant site. Among the doped systems, Cr and Mn doped phosphorene exhibit ferromagnetic ground states with critical temperatures of 217.8 K and 733.5 K, respectively. On the other hand, Ti, V and Fe doping favor antiferromagnetic ordering with relatively lower critical temperatures, 147.1 K, 58.7 K and 52.2 K, respectively. While Ti and V doping retains semiconducting character with a band gap of 0.31 eV and 0.17 eV, respectively, the Cr, Mn and Fe doped systems are found to be metallic in nature. Notably, the Fe and V doped phosphorene monolayers exhibit unconventional compensated magnetism that combines the privilege of both ferromagnetism (spin-split band structure) and antiferromagnetism (zero net magnetization). While the former doped system is identified as a quasi-altermagnetic material, the latter one is predicted to be a Luttinger compensated magnetic semiconductor. Since they can facilitate an effective spin transport without any unwanted ferromagnetic coupling, therefore, the Fe and V doped phosphorene monolayers are the preferred superior materials for applications in next-generation 2D spintronics.

The present study demonstrates the structural, elastic, thermal, and electronic properties of copper nitride (Cu₃N) doped with transition metal M (M: Fe, Co, and Ni) using pseudopotential-based density functional calculations as implemented in the Quantum ESPRESSO simulation code. The exchange-correlation is approximated by Perdew-Burke-Ernzerhof functional within the framework of generalized gradient approximation. The doped matrices, represented as Cu₃NM, are verified to be stable structures, both thermodynamically and mechanically. Tailoring of elastic properties and their anisotropy due to M doping is successfully demonstrated through a comprehensive analysis of the computed elastic stiffness coefficients, elastic moduli, elastic anisotropy factors, and spatial variation of the elastic moduli, which have not been explored yet. An increase in bulk modulus due to M doping ensures enhanced mechanical stability under isotropic stress. Conversely, while doping of Co and Ni enhances the shear resistance of the host material, Fe doping slightly reduces it. The superior ductile nature of all the studied systems predicts their suitability for applications in flexible electronics. It is evident that doping of M substantially reduces the elastic anisotropy of Cu₃N. Using the calculated elastic moduli, the velocity of acoustic waves and its anisotropy for Cu₃N and Cu₃NM are also predicted. The anisotropy in the acoustic velocity of the studied materials recommends their potential application in acoustic devices with directional selectivity. It is also noticed that, while the average acoustic velocity is reduced due to Fe doping, it increases for Co and Ni doping. Furthermore, analysis of the computed Debye temperature and minimum thermal conductivity forecasts their employability as thermal barrier coatings. Finally, the calculations reveal the ferromagnetic nature of Cu₃NFe and Cu₃NCo with respective induced magnetic moments of 2.71 and 1.47 μ _B/cell, recommending their potential applications in spintronics. It is also proved that the M-d–Cu-d coupling stabilizes the ferromagnetic ordering in such magnetic systems. On the other hand, Cu₃NNi is observed to be non-magnetic.

Magnetic skyrmions are vortex‐like spin textures, which can be manipulated by external stress or pressure via magnetoelastic effects. Herein, the observation of isostructural phase transition in a biskyrmion host hexagonal MnNiGa at pressureP ≈4 GPa using pressure‐dependent synchrotron X‐Ray powder diffraction (XRD) data analysis is presented. The XRD data reveals anisotropic compression behavior with pressure with different compression rates of thea‐axis in the basal plane and thec‐axis in the prismatic plane. However, the hexagonal symmetry remains unchanged for pressure up to 14 GPa. Fitting of unit cell volume with pressure using a second‐order Birch–Murnaghan equation of state reveals that the data fall into two distinct curves for those above and below 4 GPa. Herein, the understanding of crystal structure with the application of hydrostatic pressure in the biskyrmion host MnNiGa is contributed to, wherein the skyrmion textures can be manipulated by pressure due to their magnetoelastic character.