Theoretical exploration of Be Ag(II) F phases and their magnetic properties using learning algorithms

Katarzyna Kuder; Wojciech Grochala

Home/Archive/arXiv

arXiv · 2607.08372

Theoretical exploration of Be Ag(II) F phases and their magnetic properties using learning algorithms

Katarzyna Kuder·Wojciech Grochala

View original source ↗Read source document ↗Export metadata ↓

Abstract

The search for novel silver(II) fluorides is driven by their potential as electronic and magnetic analogues to high temperature cuprate(II) superconductor precursors. Here, we explore the previously uncharted Be Ag(II) F chemical space using global structure prediction algorithms combined with first principles calculations. Focusing on the AgBeF4 stoichiometry, we identify the five lowest enthalpy polymorphs crystallizing in the C2, P minus 1, and P 21/c space groups. All polymorphs show an antiferromagnetic ground state, with AgBeF4_4 and AgBeF4_5 exhibiting unprecedented strong superexchange interactions of J equal circa to minus 460meV and J equal circa to minus 359meV respectively. Those high J values are due to the presence of either [Ag2F7] for AgBeF4_4, or related infinite [AgF2/2+2/1]2 minus chains for AgBeF4_5. Although the phases are found to be metastable with respect to binary difluorides, the thermodynamic analysis suggests that they could be targeted via synthetic routes employing fluorine radicals, with reaction enthalpies reaching minus 370 kJ/mol.

Explore related subjects

cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el

Keep this discovery

BibTeX RIS

Katarzyna Kuder, Wojciech Grochala. 2026-07-09. Theoretical exploration of Be Ag(II) F phases and their magnetic properties using learning algorithms. https://arxiv.org/abs/2607.08372

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Out-of-equilibrium relaxation dynamics of the superconducting order parameter in CsV$_3$Sb$_5$

The application of a time-varying strain field drives a superconducting order parameter out of equilibrium. How the order parameter relaxes back to equilibrium depends both on the structure of the superconducting gap and on the nature of quasiparticle scattering. We report the discovery of an ultrasonic attenuation peak inside the superconducting state of the kagome superconductor CsV$_3$Sb$_5$. This peak is the natural consequence of the order parameter relaxation time matching the ultrasonic drive frequency near $T_{\rm c}$. From the measured frequency dependence of the peak, we extract a microscopic scattering time of $\tau_N = 25$ ps. This timescale is two orders of magnitude longer than the elastic scattering time as determined by resistivity measurements, but is comparable to the inelastic scattering time determined by thermal transport. Within the conventional framework of order-parameter relaxation, this implies that elastic scattering is ineffective at relaxing the superconducting condensate, consistent with a sign-preserving $s$-wave state obeying Anderson's theorem.

cond-mat.supr-con↗

arXiv2026

Eight-unit-cell electronic modulations in cuprates originating from local molecular orbitals

The pair density wave (PDW) state with eight-unit-cell (8a0) periodicity has been widely regarded as the primary order in cuprates, yet its existence and origin remain subjects of intense debate. Using spectroscopic imaging scanning tunneling microscopy, we observe spatial modulations of the electronic states with approximately 8a0 periodicity in both the superconducting and insulating regimes of hole-doped Ca2CuO2Cl2 cuprate. We find that the 8a0 spatial patterns are generated by the formation of molecular orbitals by doped holes, which organize into 4a0*4a0 plaquettes as the basic unit. Our results identify the 4a0 molecular orbital as the fundamental electronic building block in cuprates, while the 8a0 PDW represents a spatial subharmonic that emerges at sufficiently high doping.

cond-mat.supr-con↗

arXiv2026

Record-Breaking Elemental Superconductivity in Tetralayer Kagome Borophene

Superconductivity above the liquid-nitrogen temperature remains rare in two-dimensional elemental crystals, where strong covalent bonding often yields high phonon frequencies but insufficient electron-phonon coupling. Here, using first-principles calculations and fully anisotropic Migdal-Eliashberg theory, we predict tetralayer kagome borophene (TKB) stabilized by ABAB covalent stacking, as a liquid-nitrogen-temperature elemental superconductor. With a predicted critical temperature of 102 K, TKB sets a record-high value among previously reported elemental superconductors. Unlike known high-Tc boron-based superconductors dominated by in-plane sigma-bonding states and high-frequency in-plane B-B stretching modes, TKB realizes an out-of-plane s-pz-bonding-mediated pairing mechanism, in which interlayer s-pz bonding states at the Fermi level are strongly coupled to low-frequency out-of-plane vibrations of boron atoms. These results reveal a distinct out-of-plane pairing channel in multilayer borophene and establish covalent stacking engineering as a potential route for high-Tc superconductivity in two-dimensional materials.

cond-mat.supr-con↗