Ilia Mikhailov | Searcharxiv

arXiv2026

Complex Magnetic Behavior in RuO$_2$ Thin Films Driven by Strain and Substrate Effects

Ruthenium dioxide (RuO$_2$) has been proposed as a prototypical metallic $d$-wave altermagnet, a Néel-ordered compensated antiferromagnetic state exhibiting nonrelativistic momentum-dependent spin splitting; yet, its magnetic ground state remains controversial both theoretically and experimentally. Using comprehensive first-principles calculations, we investigate RuO$_2$ thin films with (110), (100), and (001) orientations, both (un)strained freestanding and supported on a TiO$_2$ substrate. We show that emergent magnetic moments in RuO$_2$ thin films are highly fragile, strongly influenced by strain, surface orientation, and atomic relaxation, while also being highly sensitive to the choice of the Brillouin-zone integration scheme. We find that none of the thin film structures considered can stabilize a compensated antiferromagnetic order; therefore, an altermagnetic ground state cannot be realized. Instead, substrate-supported RuO$_2$ films on TiO$_2$ exhibit pronounced layer- and site-dependent magnetic moment variations and incomplete compensation between the two antiferromagnetically coupled Ru moments, yielding a \emph{ferrimagnetic-like} behavior. On the other hand, freestanding RuO$_2$ films display complex magnetic structures depending on their orientation and applied strain, with distinct behavior at the surfaces and in the inner layers. Our results reconcile conflicting theoretical and experimental reports and underscore the sensitivity of RuO$_2$ magnetism to structural and methodological details.

cond-mat.mtrl-sci↗

arXiv2024

Quantum chemical study of the influence of torsional deformation on the properties of chiral WXY (X, Y = S, Se) Janus-nanotubes

This work sheds light on the electronic band properties of chiral WSSe Janus nanotubes from the quantum mechanical perspective. Line groups theory developed by Damnjanovich was used to model mechanical torsion of chiral nanotubes with different symmetries. Known natural torsion in chiral nanotubes was observed. It was shown that mechanical stress can be used as a tool to tune electronic properties of the nanotubes including the change of the nature of the electron transition. On the DFT-level of the theory the stability of WS2, WSe2 and Janus WSSe nanotubes was estimated. Applicability of stable Janus-nanotubes to photocatalytic water-splitting was suggested based on the calculated electronic properties

cond-mat.mtrl-sci↗

arXiv1997

Renormalised perturbative series for the impurity levels in a quantum well

The energy levels of an impurity center in a deep quantum well of width L and depth g are studied analytically . Renormalised perturbative series are constructed in the regions g L^ << 1 and g L^2 >> 1. Maximal binding energy and wave function deformation to a quasi-twodimensional function are found to occur at a certain L_c satisfying sqrt{g} L_c ~ 1. Similar results may be obtained for the impurity in a quantum wire, in a dot or in a multiwell structure.

cond-mat.mes-hall↗