arXiv subjects

M. Šiškins

Publications and source records attributed to M. Šiškins.

5 recordsLinked to original sources

arXiv2026

Integrating spin glass dynamics into nanomechanical resonators

Spin glasses are non-equilibrium magnetic systems with pronounced slow relaxation, ageing, and chaotic, synaptic-like properties, whose unique history-dependent dynamics have remained difficult to harness in functional devices. Two-dimensional van der Waals spin-glass magnets offer a route to overcome this limitation by allowing controlled coupling between magnetic and mechanical degrees of freedom. Here, we demonstrate the integration of a spin-glass functionality in nanoelectromechanical systems (NEMS) using thin exfoliated NbFeTe$_2$ films, which establishes a robust spin-glass state down to a few tens of nanometer-thick layers. Using cryogenic magnetic force microscopy, we reveal characteristic slow, hour-scale macroscopic magnetic relaxation, associated with glassy reorganisation of its magnetic domain clusters. Incorporation of thin NbFeTe$_2$ into membrane resonators allows the transduction of this glassy magnetic domain relaxation into strain, shifting their mechanical resonance frequency. This provides a functional nanomechanical readout of spin-glass dynamics and establishes a versatile platform for integrating frustrated magnetism into NEMS.

cond-mat.mes-hall↗

arXiv2023

Ultrafast laser-induced spin-lattice dynamics in the van der Waals antiferromagnet CoPS3

CoPS3 stands out in the family of the van der Waals antiferromagnets XPS3 (X=Mn, Ni, Fe, Co) due to the unquenched orbital momentum of the magnetic Co2+ ions which is known to facilitate the coupling of spins to both electromagnetic waves and lattice vibrations. Here, using a time-resolved magneto-optical pump-probe technique we experimentally study the ultrafast laser-induced dynamics of mutually correlated spins and lattice. It is shown that a femtosecond laser pulse acts as an ultrafast heater and thus results in the melting of the antiferromagnetic order. At the same time, the resonant pumping of the 4T1g - 4T2g electronic transition in Co2+ ions effectively changes their orbital momentum, giving rise to a mechanical force that moves the ions in the direction parallel to the orientation of their spins, thus generating a coherent Bg phonon mode at the frequency of about 4.7 THz.

cond-mat.mtrl-sci↗

arXiv2022

Tension tuning of sound and heat transport in graphene

Heat transport by acoustic phonons in 2D materials is fundamentally different from that in 3D crystals because the out-of-plane phonons propagate in a unique way that strongly depends on tension and bending rigidity. Since in-plane and out-of-plane phonon baths are decoupled, initial studies suggested they provide independent pathways for heat transport and storage in 2D materials. Here, we induce tension in freestanding graphene membranes by electrostatic force, and use optomechanical techniques to demonstrate that it can change the rate of heat transport by as much as 33%. Using a ballistic Debye model, we account for these observations and extract the average bending rigidity of the flexural acoustic phonons, which increases approximately linearly with the membrane's areal mass density, in contrast to the cubic dependence seen in bulk structures. Thus, we not only elucidate phononic heat transport mechanisms in suspended 2D materials, but also provide a promising route for controlling nanoscale heat transport by tension.

cond-mat.mes-hall↗

arXiv2020

Controlling the anisotropy of a van der Waals antiferromagnet with light

Magnetic van der Waals materials provide an ideal playground for exploring the fundamentals of low-dimensional magnetism and open new opportunities for ultrathin spin processing devices. The Mermin-Wagner theorem dictates that as in reduced dimensions isotropic spin interactions cannot retain long-range correlations; the order is stabilized by magnetic anisotropy. Here, using ultrashort pulses of light, we demonstrate all-optical control of magnetic anisotropy in the two-dimensional van der Waals antiferromagnet NiPS$_3$. Tuning the photon energy in resonance with an orbital transition between crystal-field split levels of the nickel ions, we demonstrate the selective activation of a sub-THz two-dimensional magnon mode. The pump polarization control of the magnon amplitude confirms that the activation is governed by the instantaneous magnetic anisotropy axis emergent in response to photoexcitation of orbital states with a lowered symmetry. Our results establish pumping of orbital resonances as a universal route for manipulating magnetic order in low-dimensional (anti)ferromagnets.

cond-mat.mtrl-sci↗

arXiv2020

Coupling lattice instabilities across the interface in ultrathin oxide heterostructures

Oxide heterointerfaces constitute a rich platform for realizing novel functionalities in condensed matter. A key aspect is the strong link between structural and electronic properties, which can be modified by interfacing materials with distinct lattice symmetries. Here we determine the effect of the cubic-tetragonal distortion of $\text{SrTiO}_3$ on the electronic properties of thin films of $\text{SrIrO}_3$, a topological crystalline metal hosting a delicate interplay between spin-orbit coupling and electronic correlations. We demonstrate that below the transition temperature at 105 K, $\text{SrIrO}_3$ orthorhombic domains couple directly to tetragonal domains in $\text{SrTiO}_3$. This forces the in-phase rotational axis to lie in-plane and creates a binary domain structure in the $\text{SrIrO}_3$ film. The close proximity to the metal-insulator transition in ultrathin $\text{SrIrO}_3$ causes the individual domains to have strongly anisotropic transport properties, driven by a reduction of bandwidth along the in-phase axis. The strong structure-property relationships in perovskites make these compounds particularly suitable for static and dynamic coupling at interfaces, providing a promising route towards realizing novel functionalities in oxide heterostructures.

cond-mat.mtrl-sci↗