arXiv subjects

Thiago T. Dorini

Publications and source records attributed to Thiago T. Dorini.

4 recordsLinked to original sources

arXiv2026

Understanding oxide surface stability: Theoretical insights from silver chromate

Silver chromate ($\mathrm{Ag_{2}CrO_{4}}$) has attracted considerable attention in recent years due to its promising photocatalytic performance, which strongly depends on the crystallographic orientation of its exposed surfaces. A detailed understanding of the structural stability of these surfaces under realistic conditions is therefore essential for advancing its applications. In this work, we combine density functional theory (DFT) with first-principles atomistic thermodynamics to systematically investigate the stability of multiple surface orientations and terminations of $\mathrm{Ag_{2}CrO_{4}}$. The surface Gibbs free energy was evaluated as a function of oxygen and silver chemical potentials, enabling the construction of stability trends under non-vacuum environments. Our results reveal that the degree of coordination of surface chromium-oxygen clusters plays a decisive role in determining surface stability. Furthermore, Wulff constructions predict morphology evolution as a function of external conditions, allowing us to identify the atomic structures of the exposed facets in the equilibrium crystal shape. These insights provide a fundamental framework for understanding surface-dependent photocatalytic activity in $\mathrm{Ag_{2}CrO_{4}}$ and related silver-based oxides.

cond-mat.mtrl-sci↗

arXiv2022

Evidence for multiband superconductivity and charge density waves in Ni-doped ZrTe$_2$

We carried out a comprehensive study of the electronic, magnetic, and thermodynamic properties of Ni-doped ZrTe$_2$. High quality Ni$_{0.04}$ZrTe$_{1.89}$ single crystals show a possible coexistence of charge density waves (CDW, T$_{CDW}\approx287$\,K) with superconductivity (T$_c\approx 4.1$\,K), which we report here for the first time. The temperature dependence of the lower (H$_{c_1}$) and upper (H$_{c_2}$) critical magnetic fields both deviate significantly from the behaviors expected in conventional single-gap s-wave superconductors. However, the behaviors of the normalized superfluid density $ρ_s(T)$ and H$_{c_2}(T)$ can be described well using a two-gap model for the Fermi surface, in a manner consistent with conventional multiband superconductivity. Electrical resistivity and specific heat measurements show clear anomalies centered near 287\,K consistent with a CDW phase transition. Additionally, electronic-structure calculations support the coexistence of electron-phonon multiband superconductivity and CDW order due to the compensated disconnected nature of the electron- and hole-pockets at the Fermi surface. Our electronic structure calculations also suggest that ZrTe$_2$ could reach a non-trivial topological type-II Dirac semimetallic state. These findings highlight that Ni-doped ZrTe2 can be uniquely important for probing the coexistence of superconducting and CDW ground states in an electronic system with non-trivial topology.

cond-mat.supr-con↗

arXiv2021

T2 phase site occupancies in the Cr--Si--B system: a combined synchroton-XRD/first-principles study

Boron and Silicon site occupancies of the T2 phase in the Cr-Si-B system were investigated experimentally and by first-principles electronic-structure calculations within the scope of the Density Functional Theory (DFT). A sample with nominal composition Cr$_{0.625}$B$_{0.175}$Si$_{0.2}$ was arc-melted under argon, encapsulated in a quartz-tube and heat-treated at 1400°C for 96 hours. It was then analyzed using Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD) with synchrotron radiation. An excellent agreement was obtained between experiments and theoretical calculations, revealing that Si occupies preferably the $4a$ sublattice of the structure due to the presence of weak B bonds, making the site preferences a key factor for its stabilization. The results of this work provide important information to support a better description of this phase in alloys with Si and B, since T2 phases are known to occur in many important Transition Metal-Si-B ternary systems, such as Nb/Mo/W/Ta/V-Si-B.

cond-mat.mtrl-sci↗

arXiv2021

Strain-engineering the topological type-II Dirac semimetal NiTe$_2$

In the present work, we investigated the electronic and elastic properties in equilibrium and under strain of the type-II Dirac semimetal NiTe$_2$ using density functional theory (DFT). Our results demonstrate the tunability of Dirac nodes' energy and momentum with strain and that it is possible to bring them closer to the Fermi level, while other metallic bands are supressed. We also derive a minimal 4-band effective model for the Dirac cones which accounts for the aforementioned strain effects by means of lattice regularization, providing an inexpensive way for further theoretical investigations and easy comparison with experiments. On an equal footing, we propose the static control of the electronic structure by intercalating alkali species into the van der Waals gap, resulting in the same effects obtained by strain-engineering and removing the requirement of in situ strain. Finally, evaluating the wavefunction's symmetry evolution as the lattice is deformed, we discuss possible consequences, such as Liftshitz transitions and the coexistence of type-I and type-II Dirac cones, thus motivating future investigations.

cond-mat.mtrl-sci↗