arXiv subjects

Pedro H. A. Moya

Publications and source records attributed to Pedro H. A. Moya.

3 recordsLinked to original sources

arXiv2026

Electronic band structure reconstruction in Ni$_{x}$ZrTe$_{2}$

The filling of the large van der Waals gap in Transition Metal Dichalcogenides (TMDs) often leads to lattice and electronic instabilities, which prelude the onset of a rich phenomenology. Here, we investigate the electronic structure of the TMDs ZrTe$_2$ and Ni-intercalated ZrTe$_2$ (Ni$_x$ZrTe$_2$, $x\approx 0.05$) employing angle-resolved photoemission spectroscopy (ARPES). We readily identify in Ni$_x$ZrTe$_2$ two flat bands, most likely associated with localized Ni-derived 3$d$-states, at about $\approx-0.7$ eV and $\approx-1.2$ eV in binding energy. The presence of these flat bands is observed for all temperatures ($T$) in our study. More significantly, at low-$T$, we identify an electronic structure reconstruction in Ni$_x$ZrTe$_2$, which halves the electronic periodicity along the $k_{z}$ direction. This is reminiscent of a commensurate band folding with wave-vector $q=(0,0,π)$. Together with previous results from macroscopic measurements, namely heat capacity and resistivity, our findings suggest that Ni intercalation drives a structural instability at $T^{*}=287$ K, which causes the observed electronic band reconstruction. Our findings invite further investigation into the structural properties of ZrTe$_2$ and of the intercalated and defect-engineered versions of this material.

cond-mat.str-el↗

arXiv2024

Hole doping and electronic correlations in Cr-substituted BaFe$_{2}$As$_{2}$

Superconductivity (SC) is absent in Cr-substituted BaFe$_{2}$As$_{2}$ (CrBFA), a well-established but poorly understood topic. Additionally, the suppression of the spin density wave transition temperature ($T_{\text{SDW}}$) in CrBFA and Mn-substituted BaFe$_{2}$As$_{2}$ (MnBFA) coincides as a function of Cr/Mn content, despite the distinct electronic effects of these substitutions. In this work, we employ angle-resolved photoemission spectroscopy (ARPES) and combined density functional theory plus dynamical mean field theory calculations (DFT+DMFT) to address the evolution of the Fermi surface (FS) and electronic correlations in CrBFA. Our findings reveal that incorporating Cr leads to an effective hole doping of the states near the FS, which is well described within the virtual crystal approximation (VCA). We analyzed the electronic band spectra with main $d_{yz}$-orbital character and found a fractional scaling of the imaginary part of self-energy as a function of the binding energy, a signature property of Hund's correlations. We conclude that CrBFA is a correlated electron system and the changes in the FS as a function of Cr are unrelated to the suppression of $T_{\text{SDW}}$. We suggest that the absence of SC is primarily due to the competition between Cr local moments and the Fe-derived itinerant spin fluctuations.

cond-mat.str-el↗

arXiv2023

Incoherent electronic band states in Mn-substituted BaFe$_{2}$As$_{2}$

Chemical substitution is commonly used to explore new ground states in materials, yet the role of disorder is often overlooked. In Mn-substituted BaFe$_{2}$As$_{2}$ (MnBFA), superconductivity (SC) is absent, despite being observed for nominal hole-doped phases. Instead, a glassy magnetic phase emerges, associated with the $S=5/2$ Mn local spins. In this work, we present a comprehensive investigation of the electronic structure of MnBFA using angle-resolved photoemission spectroscopy (ARPES). We find that Mn causes a small and orbital-specific reduction of the electron pockets, only partially disrupting nesting conditions. Based upon the analysis of the spectral properties, we observe, for all bands, an increase in the electronic scattering rate as a function of Mn content. This is interpreted as increasing band incoherence, which we propose as the primary contributor to the suppression of the magnetic order in MnBFA. This finding connects the MnBFA electronic band structure properties to the glassy magnetic behavior observed in these materials and suggests that SC is absent because of the collective magnetic impurity behavior that scatters the Fe-derived excitations. Additionally, our analysis shows that the binding energy ($E_{B}$) dependence of the imaginary part of the self-energy [$\text{Im}Σ(E_{B})$] is best described by a fractional scaling ($\text{Im}Σ(E_{B})\propto\sqrt{-E_{B}}$). These results indicate that Mn tunes MnBFA into an electronic disordered phase between the correlated Hund's metal in BaFe$_{2}$As$_{2}$ and the Hund's insulator in BaMn$_{2}$As$_{2}$.

cond-mat.supr-con↗