Todas as Publicações do INCT-MI

@workingpaper{fujisawa2025universalramanspectroscopicframework,

title = {A Universal Raman Spectroscopic Framework for Defect Quantification in Mono-to-Multilayer Graphenic Materials: The Graphene Atlas},

author = {Kazunori Fujisawa and Bruno R. Carvalho and Pedro Venezuela and Cheon-Soo Kang and Yoong Ahm Kim and Takuya Hayashi and Mauricio Terrones},

url = {https://arxiv.org/abs/2503.12459},

year  = {2025},

date = {2025-03-16},

urldate = {2025-01-01},

abstract = {Point defects, though atomically small, significantly influence the properties of 2D materials. A general method for characterizing point defect density (nD) in graphenic materials with arbitrary layer number (nL) is currently lacking. Here, we introduce the Graphene Atlas, a non-destructive Raman spectroscopy-based framework for defect quantification in diverse graphenic systems. We demonstrate that the relative fractions of the double-resonance D and 2D Raman bands, which arise from competing scattering processes, exhibit a universal relationship with nD, independent of nL. Plotting Raman data on a plane defined by defect-related and layer number-related parameters enables a direct and quantitative determination of nD and nL. This Graphene Atlas provides a transformative tool for real-time defect quantification in scalable manufacturing of graphenic materials, bridging fundamental research and industrial applications. This framework establishes a new standard for defect characterization of graphenic systems, facilitating their optimization for advanced technological applications. },

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{luna2025machinelearninginteratomicpotentialtwisted,

title = {Machine-Learning Interatomic Potential for Twisted Hexagonal Boron Nitride: Accurate Structural Relaxation and Emergent Polarization},

author = {Wilson Nieto Luna and Robin Smeyers and Cem Sevik and Lucian Covaci and Milorad V. Milošević},

url = {https://arxiv.org/abs/2503.11797},

year  = {2025},

date = {2025-03-14},

urldate = {2025-01-01},

abstract = {The emerging ferroelectric properties of two-dimensional (2D) heterostructures are at the forefront of science and prospective technology. In moiré bilayers, twisting or heterostructuring causes local atomic reconstruction, which even at picometer scale, can lead to pronounced ferroelectric polarization. Accurately determining this reconstruction utilizing ab initio methods is unfeasible for the relevant system sizes, but modern machine-learning interatomic potentials offer a viable solution. Here, we present the Gaussian Approximation Potential for twisted hexagonal boron nitride (hBN) layers validated against ab initio datasets. This approach enables the precise analysis of their structural properties, which is particularly relevant at small twist angles. We couple the structural information to a tight-binding model based on accurate interatomic positioning, and determine the twist-dependent polarization, yielding results that closely align with previous experimental findings - even at room temperature. This methodology enables further studies that are unattainable otherwise and is transferable to other 2D materials of interest. },

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{dias2025catenarylikerippledbiphenylenegraphenelateral,

title = {Catenary-like rippled biphenylene/graphene lateral heterojunction},

author = {Victor M. S. C. Dias and Danilo P. Kuritza and Igor S. S. Oliveira and Jose E. Padilha and Roberto H. Miwa},

url = {https://arxiv.org/abs/2503.07816},

doi = { 	 https://doi.org/10.48550/arXiv.2503.07816},

year  = {2025},

date = {2025-03-10},

urldate = {2025-01-01},

abstract = {In this study, we conduct a first-principles analysis to explore the structural and electronic properties of curved biphenylene/graphene lateral junctions (BPN/G). We start our investigation focusing on the energetic stability of BPN/G by varying the width of the graphene region, BPN/Gn. The electronic structure of BPN/Gn reveals (i) the formation of metallic channels mostly localized along the BPN stripes, where (ii) the features of the energy bands near the Fermi level are ruled by the width (n) of the graphene regions, Gn. In the sequence, we find that the hydrogenation of BPN/Gn results in a semiconductor system with a catenary-like rippled geometry. The electronic states of the hydrogenated system are mainly confined in the curved Gn regions, and the dependence of the bandgap on the width of Gn is similar to that of hydrogenated armchair graphene nanoribbons. The effects of curvature on the electronic structure, analyzed in terms of external mechanical strain, revealed that the increase/decrease of the band gap is also dictated by the width of the Gn region. Further electronic transport calculations reveal a combination of strong transmission anisotropy and the emergence of negative differential resistance. Based on these findings, we believe that rippled biphenylene/graphene systems can be useful for the design of two-dimensional nanodevices. },

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{deoliveira2025formationmechanismstabilityrole,

title = {Formation mechanism, stability and role of zinc and sulfur vacancies on the electronic properties and optical response of ZnS},

author = {P. R. A Oliveira and L. Lima and G. Felix and Pedro Venezuela and F. Stavale},

url = {https://arxiv.org/abs/2502.15670},

year  = {2025},

date = {2025-02-21},

urldate = {2025-01-01},

abstract = {Combining experimental and theoretical tools, we report that Zn vacanciesplay an important role in the electronic and optical responses of ZnS sphalerite. The defective surface of ZnS (001) single crystal prepared in ultra-highvacuum conditions, has been shown to exhibit a semiconducting character instead of the insulating properties of the pristine structure, as revealed by X-ray photoelectron spectroscopy (XPS). Interestingly, this effect is attributed to the formation of zinc vacancies in the ZnS system, which also alter the optical response of the material, as supported by photoluminescence (PL) measurements comparing pristine and S-rich (Zn-poor) ZnS. To address these findings from a theoretical point of view, first principles calculations based on density functional theory (DFT) were performed. The optical properties of cation-defective ZnS were evaluated using random-phase approximation and hybrid functional DFT calculations. These calculations revealed absorption peaks in the visible range in the defective ZnS rather than solely in the ultra-violet range obtained for defect-free ZnS. The combination of this finding with joint density of states (JDOS) analysis explains the emergence of new luminescence peaks observed in the PL spectra of cation-defective ZnS. These findings highlight the role of Zn vacancies in tuning ZnS optical properties, making it a potential candidate for optoelectronic applications such as LEDs and photodetectors.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{cysne2025orbitronicstwodimensionalmaterials,

title = {Orbitronics in Two-dimensional Materials},

author = {Tarik P. Cysne and Luis M. Canonico and Marcio Costa and R. B. Muniz and Tatiana G. Rappoport},

url = {https://arxiv.org/abs/2502.12339},

year  = {2025},

date = {2025-02-17},

urldate = {2025-01-01},

abstract = {Orbitronics explores the control and manipulation of electronic orbital angular momentum in solid-state systems, opening new pathways for information processing and storage. One significant advantage of orbitronics over spintronics is that it does not rely on spin-orbit coupling, thereby broadening the range of non-magnetic materials that can be utilized for these applications. It also introduces new topological features related to electronic orbital angular momentum, and clarifies some long-standing challenges in understanding experiments that rely on the conventional concept of valley transport. This review highlights recent advances in orbitronics, particularly in relation to two-dimensional materials. We examine the fundamental principles underlying the generation, transport, and dynamics of orbital angular momentum to illustrate how the unique properties of two-dimensional materials can promote orbitronic phenomena. We also outline potential future research directions and address some outstanding questions in this field.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{cardias2025edgenoncollinearmagnetismnanoribbons,

title = {Edge non-collinear magnetism in nanoribbons of Fe3GeTe2 and Fe3GaTe2},

author = {R. Cardias and Anders Bergman and Hugo U. R. Strand and R. B. Muniz and Marcio Costa},

url = {https://arxiv.org/abs/2502.12356},

year  = {2025},

date = {2025-02-17},

urldate = {2025-01-01},

abstract = {Fe3GeTe2 and Fe3GaTe2 are ferromagnetic conducting materials of van der Waals-type with unique magnetic properties that are highly promising for the development of new spintronic, orbitronic and magnonic devices. Even in the form of two-dimensional-like ultrathin films, they exhibit relatively high Curie temperature, magnetic anisotropy perpendicular to the atomic planes and multiple types of Hall effects. We explore nanoribbons made from single layers of these materials and show that they display non-collinear magnetic ordering at their edges. This magnetic inhomogeneity allows angular momentum currents to generate magnetic torques at the sample edges, regardless of their polarization direction, significantly enhancing the effectiveness of magnetization manipulation in these systems. We also demonstrate that it is possible to rapidly reverse the magnetization direction of these nanostructures by means of spin-orbit and spin-transfer torques with rather low current densities, making them quite propitious for non-volatile magnetic memory units.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{goswami2025exceptionallyhighnonlinearoptical,

title = {Exceptionally High Nonlinear Optical Response in Two-dimensional Type II Dirac Semimetal Nickel di-Telluride (NiTe2)},

author = {Saswata Goswami and Caique Campos Oliveira and Bruno Ipaves and Preeti Lata Mahapatra and Varinder Pal and Suman Sarkar and Pedro A. S. Autreto and Samit K. Ray and Chandra Sekhar Tiwary},

url = {https://arxiv.org/abs/2502.10781},

year  = {2025},

date = {2025-02-15},

urldate = {2025-02-15},

abstract = {Nickel ditelluride (NiTe2) is a newly identified Type-II Dirac semimetal, showing novel characteristics in electronic transport and optical experiments. In this study, we explored the nonlinear optical properties of two-dimensional NiTe2 using experimental and computational techniques (density functional theory-based approach). Few layered two-dimensional NiTe2 (2D-NiTe2) are synthesized using liquid phase exfoliation (LPE), which is characterized using X-ray diffraction technique, transmission electron, and atomic force microscopy. The nonlinear refractive index and third-order nonlinear susceptibility of the prepared 2D-NiTe2 are determined from the self-induced diffraction pattern generated using different wavelengths ( 405, 532, and 650 nm) in the far field. In addition, the diffraction pattern generated by spatial self-phase modulation (SSPM) is further verified by varying concentration (2D-NiTe2 in the IPA solvent), wavelength (of incoming laser beams), and cuvette width (active path length). The high value of third-order nonlinear susceptibility (in order of 10-9 e.s.u.) determined using SSPM in the 2D-NiTe2 can be attributed to the laser-induced hole coherence effect. Lastly, utilizing the reverse saturable absorption property of 2D-hBN, asymmetric light propagation is also demonstrated in the 2D-NiTe2/2D-hBN heterostructure.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{ipaves2025enhancingcatalystactivitytwodimensional,

title = {Enhancing catalyst activity of two-dimensional C4N2 through doping for the hydrogen evolution reaction},

author = {Bruno Ipaves and João F. Justo and James M. de Almeida and Lucy V. C. Assali and Pedro A. S. Autreto},

url = {https://arxiv.org/abs/2502.10863},

year  = {2025},

date = {2025-02-15},

urldate = {2025-01-01},

abstract = {This study investigates the structural, electronic, and catalytic properties of pristine and doped C4N2 nanosheets as potential electrocatalysts for the hydrogen evolution reaction. The pristine C36N18 nanosheets exhibit limited HER activity, primarily due to high positive Gibbs free energies (> 2.2 eV). To enhance catalytic performance, doping with B, Si, or P at the nitrogen site was explored. Among these systems, B-doped C36N17 nanosheets exhibit the most promising catalytic activity, with a Gibbs free energy close to zero (≈ -0.2 eV), indicating efficient hydrogen adsorption. Band structure, projected density of states, charge density, and Bader charge analyses reveal significant changes in the electronic environment due to doping. While stacking configurations (AA′A′′ and ABC) have minimal effect on catalytic performance, doping - particularly with B -substantially alters the electronic structure, optimizing hydrogen adsorption and facilitating efficient HER. These findings suggest that B-doped C36N17 nanosheets could serve as efficient cocatalysts when combined with metallic materials, offering a promising approach to enhance catalytic efficiency in electrocatalytic and photocatalytic applications.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{shafiei2025lightinduceddissipationlessstatesmagnetic,

title = {Light-induced dissipationless states in magnetic topological insulators with hexagonal warping},

author = {Mohammad Shafiei and Milorad V. Milošević},

url = {https://arxiv.org/abs/2502.10164},

year  = {2025},

date = {2025-02-14},

urldate = {2025-01-01},

abstract = {Magnetic impurities in topological insulators (TIs) induce backscattering via magnetic torque, unlike pristine TIs where spin-orbit locking promotes dissipationless surface states. Here we reveal that one can suppress that unwanted backscattering and dissipation in magnetic TIs using high-frequency linearly polarized light (LPL). By carefully considering the hexagonal warping of the Fermi surface of the TI, we demonstrate how the coupling between Dirac surface states and LPL can effectively reduce backscattering on magnetic dopants, enhance carrier mobility and suppress resistance, even entirely. These findings open up avenues for designing ultra low-power sensing and spintronic technology.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{serquen2025crystallineenvironmentluminescenttb3,

title = {On the crystalline environment of luminescent Tb3+ ions embedded in indium tin oxide thin films: a DFT and Crystal field analysis assessment},

author = {E. Serquen and K. Lizárraga and L. A. Enrique and F. Bravo and S. Mishra and P. LLontop and Pedro Venezuela and L. R. Tessler and J. A. Guerra},

url = {https://arxiv.org/abs/2502.08517},

doi = { https://doi.org/10.48550/arXiv.2502.08517},

year  = {2025},

date = {2025-02-12},

urldate = {2025-02-12},

abstract = {We assess the local symmetry and crystal environment of trivalent terbium ions embedded in an indium tin oxide (ITO) matrix with bixbyite structure. The mbox{Tb3+} ions tend to substitute mbox{In3+} ions in two different cationic sites (b and d). Density Functional Theory (DFT) calculations suggest that the mbox{Tb3+} ions are mainly located at C2 symmetry sites relaxing selection rules and enabling electric dipole transitions, with the $^5text{D}_4rightarrowleftindex^7{text{F}}_2$ transition being the most intense, providing a red color to the light emission. Photoluminescence emission spectra under UV excitation at qty{83}{kelvin} revealed 30 intra-4f transitions, which were assigned to the $leftindex^7{text{F}}_J$ ground multiplet of the mbox{Tb3+} ion. Crystal-field analysis shows a strong alignment between calculated and observed energy levels, yielding a standard deviation of $sigma=qty{15.1}{centipermetre}$. We believe these results can help to understand the activation mechanisms of mbox{Tb3+} luminescent centers in transparent conductive oxides, as well as the potential to modulate mbox{Tb3+} emission color through its crystalline environment.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{šabani2025orbitallyresolvedmagneticexchangecri3,

title = {Beyond the orbitally-resolved magnetic exchange in CrI3 and NiI2},

author = {Denis Šabani and Cihan Bacaksız and Milorad V. Milošević},

url = {https://arxiv.org/abs/2502.08273},

doi = { https://doi.org/10.48550/arXiv.2502.08273},

year  = {2025},

date = {2025-02-12},

urldate = {2025-02-12},

abstract = {The pertinent need for microscopic understanding of magnetic exchange motivated us to go beyond the existing theories and develop a systematic method to quantify all possible mechanisms that contribute to magnetic exchange for an arbitrary pair of atoms in a given material. We apply it to the archetypal 2D magnetic monolayers CrI3 and NiI2, to reveal the previously underrated dx2-y2,dx2-y2 contribution as either the leading or the second largest contribution to the total magnetic exchange. We proceed to explore the microscopic mechanisms behind all the non-zero orbital contributions in both CrI3 and NiI2, and generalize the findings to other magnetic monolayers dominated by d8 and d3 electronic configurations of the magnetic atoms.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}