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A vast majority of electrical devices have integrated magnetic units, which generate constant magnetic fields with noticeable vibrations. The majority of existing nanogenerators acquire energy through friction/mechanical forces and most of these instances overlook acoustic vibrations and magnetic fields. Magnetic two-dimensional (2D) tellurides present a wide range of possibilities for devising a potential flexible energy harvester. We have synthesized two-dimensional chromium telluride (2D CrTe3) which exhibits ferromagnetic (FM) nature with a Tc of 224 K. The structure exhibits stable high remnant magnetization, making 2D CrTe3 flakes a potential material for harvesting of magneto-acoustic waves at room temperature. A magneto-acoustic nanogenerator (MANG) was fabricated composing of 2D CrTe3 dispersed in a polymer matrix. Basic mechanical stability and sensitivity of the device with change in load conditions were tested. A high surface charge density of 2.919 mC m-2 was obtained for the device. The thermal strain created in the lattice structure was examined using in-situ Raman spectroscopic measurements. The magnetic anisotropy energy (MAE) responsible for long-range FM ordering was calculated with the help of theoretical modelling. The theoretical calculations also showed opening of electronic bandgap which enhances the flexoelectric effects. The MANG can be a potential energy harvester to synergistically tap into the magneto-acoustic vibrations generated from the frequency changes of a vibrating device such as loudspeakers.

Two-dimensional (2D) chromium telluride Cr2Te3 exhibits strong ferromagnetic ordering with high coercivity at low temperatures and paramagnetic behaviour when approaching room temperature. The spin states of monolayer Cr2Te3 show ferromagnetic ordering in the ground state, and in-situ Raman analysis shows reversible structure transformation and hence a ferromagnetic to paramagnetic transition during low-temperature heating cycles (0 - 25 {\deg}C). The magnetic phase transition near room temperature in the 2D Cr2Te3 prompted the exploration of these layered materials for energy application. We demonstrate that the low-temperature ferromagnetic behavior can be used to magnetically deice material surfaces using an external magnetic source, avoiding the use of harsh chemicals and high temperatures. The hydrophobic nature and dipole interactions of H2O molecules with the surface of the 2D Cr2Te3 coating aid in the condensation of ice droplets formed on the surface. First-principles calculations also confirm the observed crystal structure, surface interaction, and magnetic properties of 2D Cr2Te3.

Two dimensional (2D) layered transition-metal-based tellurides (chalcogens) are known to harness their surface atoms characteristics to enhance topographical activities for energy conversion, storage, and magnetic applications. High surface energy due to unsaturated dangling bonds and larger lateral size than the thickness (volume) makes them a potential candidate for emerging electronics. Nevertheless, the gradual stacking of each sheet alters the surface atoms' subtle features, such as lattice expansion, leading to several phenomena and rendering tunable properties. In the present work, we have monitored thickness-dependent properties of the 2D CoTe2 sheets from nanoscale mechanics, tribology, surface potential distributions, interfacial interaction and magnetism using atomically resolved spectroscopy and different surface probe techniques, in conjunction with theoretical investigations: density functional theory (DFT) and molecular dynamics (MD). The variation in properties observed in theoretical investigation unleashes the crucial role of crystal planes of the CoTe2. The presented results are beneficial in expanding the use of 2D telluride family in flexible electronics, piezo sensors, tribo-generator, and next-generation memory devices.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) remain a topic of immense interest. Specifically, given their low operational switching costs, they find many niche applications in new computing architectures with the promise of continued miniaturization. However, challenges lie in Back End of Line (BEOL) integration temperature and time compliance regarding current requirements for crystal growth. Additionally, deleterious and time-consuming transfer processes and multiple steps involved in channel/contact engineering can cripple device performance. This work demonstrates kinetics-governed in-situ growth regimes (surface or edge growth from gold) of WSe2 and provides a mechanistic understanding of these regimes via energetics across various material interfaces. As a proof-of-concept, field effect transistors (FET) with an in-situ grown WSe2 channel across Au contacts are fabricated, demonstrating a 2D semiconductor transistor via a transfer-free method within the 450-600 C 2h-time window requirement BEOL integration. We leverage directional edge growth to fabricate contacts with robust thickness-dependent Schottky-to-Ohmic behavior. By transitioning between Au and SiO2 growth substrates in situ, this work achieves strain-induced subthreshold swing of 140 mV/decade, relatively high mobility of 107 +- 19 cm2V-1s-1, and robust ON/OFF ratios 10^6 in the fabricated FETs., Comment: 32 pages, 5 Figures

Magnetism in semiconductor two-dimensional (2D) materials is gaining popularity due to its potential application in memory devices, sensors, spintronic and biomedical applications. Here, 2D Cobalt Telluride (CoTe) has been synthesized from its bulk crystals using a simple and scalable liquid-phase exfoliation method. The atomically thin CoTe shows over four hundred times enhancement in its magnetic saturation values compared to the bulk form. The UV-Vis absorption spectra reveal superior absorption in the high energy region, suggesting a semiconducting nature. Furthermore, we explain bandgap and origin of high magnetic behavior by density functional theory (DFT) calculations. The 2D CoTe shows a larger magnetism compared to bulk CoTe due to the reduced coordination number of the surface atoms, shape anisotropy and surface charge effect.

Two dimensional (2D) materials have received a surge in research interest due to their exciting range of properties. Here we show that 2D cobalt telluride (Co2Te3), successfully synthesized via liquid-phase exfoliation in an organic solvent, exhibits weak ferromagnetism and semiconducting behavior at room temperature. The magnetic field-dependent piezoelectric properties of 2D Co2Te3 sample show magneto-electric response of the material and a linear relationship between the output voltage and applied magnetic field. First-principles density functional theory (DFT) and ab initio molecular dynamics are used to explain these experimental results. Our work could pave the way for the development of 2D materials with coupled magnetism and piezoelectricity, leading to new applications in electromagnetics.

Two-dimensional (2D) materials have been shown to be efficient in energy harvesting. Here, we report utilization of waste heat to generate electricity via combined piezoelectric and triboelectric property of 2D Cobalt Telluride (CoTe2). The piezo-triboelectric nanogenerator (PTNG) produced an open-circuit voltage of ~5V under 1N force and the effect of temperature in the 305-363 K range shows a four-fold energy conversion efficiency improvement. The 2D piezo-tribogenerator shows excellent characteristics with a maximum voltage of ~10V, fast response time and high responsivity. Density functional theory was used to gain further insights and validation of the experimental results. Our results could lead to energy harvesting approaches using 2D materials from various thermal sources and dissipated waste heat from electronic devices.

Carbon Nanotubes (CNTs)-polymer composites are promising candidates for a myriad of applications. Ad-hoc CNTs-polymer composite fabrication techniques inherently pose roadblock to optimized processing resulting in microstructural defects i.e., void formation, poor interfacial adhesion, wettability, and agglomeration of CNTs inside the polymer matrix. Although improvement in the microstructures can be achieved via additional processing steps such as-mechanical methods and/or chemical functionalization, the resulting composites are somewhat limited in structural and functional performances. Here, we demonstrate that 3D printing technique like-direct ink writing offers improved processing of CNTs-polymer composites. The shear-induced flow of an engineered nanocomposite ink through the micronozzle offers some benefits including reducing the number of voids within the epoxy, improving CNTs dispersion and adhesion with epoxy, and partially aligns the CNTs. Such microstructural changes result in superior mechanical performance and heat transfer in the composites compared to their mold-casted counterparts. This work demonstrates the advantages of 3D printing over traditional fabrication methods, beyond the ability to rapidly fabricate complex architectures, to achieve improved processing dynamics for fabricating CNT-polymer nanocomposites with better structural and functional properties., Comment: 16 pages, 6 figures

Graphene grain boundaries have attracted interest for their ability to host nearly dispersionless electronic bands and magnetic instabilities. Here, we employ quantum transport and universal conductance fluctuations (UCF) measurements to experimentally demonstrate a spontaneous breaking of time reversal symmetry (TRS) across individual GBs of chemical vapour deposited graphene. While quantum transport across the GBs indicate spin-scattering-induced dephasing, and hence formation of local magnetic moments, below $T\lesssim 4$ K, we observe complete lifting of TRS at high carrier densities ($n \gtrsim 5\times 10^{12}$cm$^{-2}$) and low temperature ($T\lesssim 2$ K). An unprecedented thirty times reduction in the UCF magnitude with increasing doping density further supports the possibility of an emergent frozen magnetic state at the GBs. Our experimental results suggest that realistic GBs of graphene can be a promising resource for new electronic phases and spin-based applications.