arXiv subjects

Izabela A. Wrona

Publications and source records attributed to Izabela A. Wrona.

5 recordsLinked to original sources

arXiv2026

Theoretical prediction of strong-coupling superconductivity in a hypothetical NaAlH3 phase at ambient pressure

We present a comprehensive first-principles investigation of a hypothetical cubic Pm-3m phase of the ternary hydride NaAlH3, focusing on its lattice dynamics, electronic structure, and electron-phonon-mediated superconducting properties at ambient pressure. Using density functional theory and the Migdal-Eliashberg formalism, we find an exceptionally strong electron-phonon coupling ($λ=2.23$), resulting in a superconducting critical temperature of up to 73.7 K for a Coulomb pseudopotential $μ^* = 0.1$. Phonon dispersion calculations, complemented by ab initio molecular dynamics simulations, indicate dynamic and thermal stability within the adopted theoretical framework. The electronic structure exhibits a metallic character with substantial contributions from Al- and Na-derived states at the Fermi level. The resulting superconducting gap ratio ($2Δ(0)/k_B T_c \approx 4.8$) and specific heat jump ($ΔC/γT_c \approx 2.2$) significantly exceed BCS weak-coupling predictions, highlighting the strong-coupling nature of superconductivity in this hypothetical phase.

cond-mat.supr-con↗

arXiv2024

A recipe for an effective selection of promising candidates for high-temperature superconductors among binary hydrides

Recent research on compressed binary hydrides have unveiled the potential for achieving superconductivity at near-room-temperature. Nevertheless, the available decision-making procedures standing behind the selection of constituent elements that may potentially exhibit high values of critical temperature ($T_c$) are far from optimal. In other words, a lot of experimental and numerical effort is wasted on exploring unpromising compounds. By conducting a deep study of a database containing over $580$ binary hydride superconductors, we were able to observe some interesting relationships between $T_c$ and selected physico-chemical properties of examined compounds. Among studied parameters, the ratio of the sum of the molecular weight of heavier atoms to the total mass of all hydrogen atoms in the chemical formula of hydride ($M_X/M_H$) was found to be the most valuable indicator that can help to screen for new promising superconductor candidates. This is because the highest $T_c$ requires the lowest $M_X/M_H$ ratio. Statistical analysis indicates a $28\%$ chance of finding $T_c > 200$ K within $0 < M_X/M_H < 15$. It is expected that these findings will not only allow for more efficient use of resources by improving future superconductor candidates selection but also they will accelerate ongoing experimental and numerical research that should bring new exciting discoveries in a much shorter time.

cond-mat.supr-con↗

arXiv2020

Superconductivity of $LaH_{10}$ and $LaH_{16}$ polyhydrides

We explore high-pressure phase stability and superconductivity of lanthanum hydrides $LaH_m$ (m=4-11,16). We predict stability of a hitherto unreported polyhydride $P6/mmm$-$LaH_{16}$ at pressures above 150 GPa; at 200 GPa its predicted superconducting $T_C$ is 156 K, critical field $μ_0$$H_C$(0) ~ 35 T and superconducting gap is up to 35 meV. We revisit superconductivity of the recently discovered $LaH_{10}$ and find its $T_C$ to be up to 259 K (170 GPa) from solving the Eliashberg equation and 271 K from solving the gap equation in SCDFT which also allowed us to compute the Coulomb pseudopotential $μ^*$ for $LaH_{10}$ and $LaH_{16}$. Presence of several polymorph modifications of LaH10 may explain the variety in the experimentally measured $T_C$ values for $LaH_{10}$ [1,2]

cond-mat.supr-con↗

arXiv2018

High-Temperature Superconductivity in Th-H System at Pressure Conditions

New stable thorium decahydride $Fm\bar{3}m$-$ThH_{10}$, a record high-temperature superconductor with $T_C$ up to 241 K ($-32^{\circ}C$), critical field $H_C$ up to 71T and superconducting gap ${Δ_0}$ = 52 meV at 80-100 GPa was predicted by evolutionary algorithm USPEX. Another phase ${P2_1c}$-$ThH_7$ was found to be a high-temperature superconductor with $T_C$ of 65 K. Analysis of superconducting state was performed within Eliashberg formalism and the dependencies of $H_C(T)$, ${Δ_0}(T)$, $T_C(P)$ together with jump in the specific heat at critical temperature were calculated. Several other new thorium hydrides were predicted to be stable under pressure including $ThH_3$, $Th_3H_{10}$, $ThH_4$, $ThH_6$. Thorium (which has $s^2d^2$ electronic configuration) forms high-$T_C$ polyhydrides similar to those formed by $s^2d^1$ metals (Y-La-Ac). Thorium - is the next member in Mg-Ca-Sc-Y-La-Ac family of elements forming high-$T_C$ superconducting hydrides.

cond-mat.supr-con↗

arXiv2018

Anomalously high value of Coulomb pseudopotential for the $\rm H_{5}S_{2}$ superconductor

The ${\rm H_{5}S_{2}}$ and ${\rm H_{2}S}$ compounds are the two candidates for the low-temperature phase of compressed sulfur-hydrogen system. We have shown that the value of Coulomb pseudopotential ($μ^{\star}$) for ${\rm H_{5}S_{2}}$ ($\left[T_{C}\right]_{\rm exp}=36$~K and $p=112$~GPa) is anomalously high. The numerical results give the limitation from below to $μ^{\star}$ that is equal to $0.402$ ($μ^{\star}=0.589$, if we consider the first order vertex corrections to the electron-phonon interaction). Presented data mean that the properties of superconducting phase in the ${\rm H_{5}S_{2}}$ compound can be understood within the classical framework of Eliashberg formalism only at the phenomenological level ($μ^{\star}$ is the parameter of matching the theory to the experimental data). On the other hand, in the case of ${\rm H_{2}S}$ it is not necessary to take high value of Coulomb pseudopotential to reproduce the experimental critical temperature relatively well ($μ^{\star}=0.15$). In our opinion, ${\rm H_{2}S}$ is mainly responsible for the observed superconductivity state in the sulfur-hydrogen system at low temperature.

cond-mat.supr-con↗