arXiv subjects

Jan Suffczyński

Publications and source records attributed to Jan Suffczyński.

At least 19 recordsLinked to original sources

arXiv2025

Terahertz magnon-polaritons control using a tunable liquid crystal cavity

Strong coupling of light to a collective spin excitation in antiferromagnets gives rise to hybrid modes called magnon-polaritons. They are highly promising for data manipulation and transfer at terahertz rates, much faster than in the case of ferromagnetic magnon-polaritons, which operate at GHz frequencies. Yet, control of terahertz magnon-polaritons by the voltage, i.e. without ohmic dissipation losses, remains challenging. Here, we showcase the ability to remotely control antiferromagnetic magnon-polaritons at room temperature using an electric field by integrating a highly birefringent liquid crystal layer into a terahertz Fabry-Pérot cavity containing an antiferromagnetic crystal. Positioned several millimeters from the magnetic material, the liquid crystal allows for electrical manipulation of the cavity's photonic environment by control of its dielectric constant. This adjustment, in turn, influences the extent of magnon dressing by cavity photons, thereby controlling the vacuum Rabi oscillations of the magnon resonance coupled to a particular cavity mode. Our approach enables reversible tuning of magnon-photon hybridization that can be triggered without direct electrical contact or alteration of the magnetic medium. These findings pave the way for voltage-programmable terahertz magnonic devices and open new avenues for noninvasive control strategies in spin-based information processing technologies.

cond-mat.other↗

arXiv2025

Deterministic hBN bubbles as a versatile platform for studies on single-photon emitters

Single-photon emitters (SPEs) in two-dimensional materials are highly promising candidates for quantum technologies. SPEs in hexagonal boron nitride (hBN) have been widely investigated, but mostly in exfoliated or powder samples that require an activation process, making it difficult to compare studies and reproduce results. Here, we address this problem and propose a platform based on large-area metaloraganic vapour phase epitaxy (MOVPE)-grown hBN, which combines reproducibility and scalability with the ability to readily host SPEs without activation. Through the creation of bubbles via electron-beam irradiation, we achieve additional functionalities, including an interference-mediated enhancement of emission by approximately 100-200\%, dedicated structures that allow the relocation of individual emitters across different systems, and the opportunity to investigate strain-induced effects. Moreover, in contrast to other gas-filled bubbles that deflate at low temperatures, our bubbles remain stable under cryogenic conditions, allowing studies as a function of temperature. To improve the control over the shape and position of bubbles, we demonstrate a~mask-based method that enables deterministic control over bubble formation. The presented hBN bubbles constitute a versatile platform for reproducible studies of hBN-based emitters, providing a reliable insight into their nature and properties.

cond-mat.mtrl-sci↗

arXiv2025

Optical bound states in the continuum in subwavelength gratings made of an epitaxial van der Waals material

High refractive index (4.4 at 1100 nm), negligibly small absorption in near-infrared spectral range, and ease of processing make MoSe$_2$ a perfect material for applications in near-infrared photonics. So far, implementation of MoSe$_2$-based photonic structures has been hindered by the lack of large surface MoSe$_2$ substrates. The use of molecular beam epitaxy allows the production of homogeneous layers of MoSe$_2$ with a few-inch surface and a thickness controlled at the sub-nm level. In the present work, we design by theoretical calculations and fabricate by a simple lithography process an ultrathin subwavelength grating out of 42-nm thick, epitaxially-grown MoSe$_2$ layer. Our polarization-resolved reflectivity measurements confirm that the gratings host a peculiar type of a confined optical mode that is a bound state in the continuum. Moreover, the fabricated structures enhance the efficiency of the third harmonic generation by over three orders of magnitude as compared to the unstructured MoSe$_2$ layer. The presented results are promising for the realization of flat, ultra-compact devices for lasing, wavefront control, and higher-order topological states of the light.

physics.optics↗

arXiv2024

Direct Optical Probing of the Magnetic Properties of the Layered Antiferromagnet CrPS$_4$

Unusual magnetic properties of Van der Waals type antiferromagnetic semiconductors make them highly attractive for spintronics and optoelectronics. A link between the magnetic and optical properties of those materials, required for practical applications, has not been, however, established so far. Here, we report on a combined experimental and theoretical study of magnetic, optical, and structural properties of bulk CrPS$_{4}$ samples. We find that the magnetic-field-dependent circular polarization degree of the photoluminescence is a direct measure of the net magnetization of CrPS$_{4}$. Complementary, Raman scattering measured as a function of magnetic field and temperature enables the determination of the magnetic susceptibility curve of the material. Our experimental results are backed by Our experimental results are supported by density functional theory calculations that take as input the lattice parameters determined from temperature-dependent X-ray diffraction measurements. This allows us to explain the impact of spin ordering on the spectral position of Raman transitions in CrPS$_4$, as well as anomalous temperature shifts of selected of them. The presented method for all-optical determination of the magnetic properties is highly promising for studies of spin ordering and magnetic phase transitions in single- or a few-layer samples of magnetic layered materials, for which a poor signal-to-noise ratio precludes any reliable neutron scattering or magnetometry measurements.

cond-mat.mtrl-sci↗

arXiv2023

Wurtzite vs rock-salt MnSe epitaxy: electronic and altermagnetic properties

Newly discovered altermagnets are magnetic materials exhibiting both compensated magnetic order, similar to antiferromagnets, and simultaneous non-relativistic spin-splitting of the bands, akin to ferromagnets. This characteristic arises from the specific symmetry operations that connect the spin sublattices. In this report, we show with ab initio calculations that the semiconductive MnSe exhibits altermagnetic spin-splitting in the wurtzite phase as well as a critical temperature well above room temperature. It is the first material from such space group identified to possess altermagnetic properties. Furthermore, we demonstrate experimentally through structural characterization techniques that it is possible to obtain thin films of both the intriguing wurtzite phase of MnSe and the more common rock-salt MnSe using molecular beam epitaxy on GaAs substrates. The choice of buffer layers plays a crucial role in determining the resulting phase and consequently extends the array of materials available for the physics of altermagnetism.

cond-mat.mtrl-sci↗

arXiv2023

Erbium-based multifuncional compounds as molecular microkelvin-tunable driving-sensing units

We demonstrate the selective control of the magnetic response and photoluminescence properties of Er3+ centers with light, by associating them with a highly conjugated beta-diketonate (1,3-di(2-naphthyl)-1,3-propanedione) ligand. We demonstrate this system to be an optically-pumped molecular compound emittingin infra-red, which can be employed as a precise heat-driving and detecting unit for low temperatures

cond-mat.mtrl-sci↗

arXiv2023

Molecular Beam Epitaxy growth of MoTe$_2$ on Hexagonal Boron Nitride

Hexagonal boron nitride has already been proven to serve as a decent substrate for high quality epitaxial growth of several 2D materials, such as graphene, MoSe$_{\tiny{\textrm{2}}}$, MoS$_{\tiny{\textrm{2}}}$ or WSe$_{\tiny{\textrm{2}}}$. Here, we present for the first time the molecular beam epitaxy growth of MoTe$_{\tiny{\textrm{2}}}$ on atomically smooth hexagonal boron nitride (hBN) substrate. Occurrence of MoTe$_{\tiny{\textrm{2}}}$ in various crystalline phases such as distorted octahedral 1T' phase with semimetal properties or hexagonal 2H phase with semiconducting properties opens a possibility of realisation of crystal-phase homostructures with tunable properties. Atomic force microscopy studies of MoTe$_{\tiny{\textrm{2}}}$ grown in a single monolayer regime enable us to determine surface morphology as a function of the growth conditions. The diffusion constant of MoTe$_{\tiny{\textrm{2}}}$ grown on hBN can be altered 5 times by annealing after the growth, reaching about 5 $\cdot$ 10$^{-6}$ cm$^{2}$/s. Raman spectroscopy results suggest a coexistence of both 2H and 1T' MoTe$_{\tiny{\textrm{2}}}$ phases in the studied samples.

cond-mat.mtrl-sci↗

arXiv2023

Optical, electronic and structural properties of ScAlMgO4

Magnesium aluminate scandium oxide (ScAlMgO4) is a promising lattice-matched substrate material for GaN- and ZnO-based optoelectronic devices. Yet, despite its clear advantages over substrates commonly used in heteroepitaxial growth, several fundamental properties of ScAlMgO4 remain unsettled. Here, we provide a comprehensive picture of its optical, electronic and structural properties by studying ScAlMgO4 single crystals grown by the Czochralski method. We use variable angle spectroscopic ellipsometry to determine complex in-plane and out-of-plane refractive indices in the range from 193 to 1690 nm. An oscillator-based model provides a phenomenological description of the ellipsometric spectra with excellent agreement over the entire range of wavelengths. For convenience, we supply the reader also with Cauchy formulas describing the real part of the anisotropic refractive index for wavelengths above 400 nm. Ab initio many-body perturbation theory modeling provides information about the electronic structure of ScAlMgO4, and successfully validated experimentally obtained refractive index values. Simulations also show exciton binding energy as large as a few hundred of meV, indicating ScAlMgO4 as a promising material for implementation in low-threshold, deep-UV lasing devices operating at room temperature. X-ray diffraction measurements confirm lattice constants of ScAlMgO4 previously reported, but in addition, reveal that dominant crystallographic planes (001) are mutually inclined by about 0.009°. In view of our work, ScAlMgO4 is a highly transparent, low refractive index, birefringent material similar to a sapphire, but with a much more favorable lattice constant and simpler processing.

cond-mat.mtrl-sci↗

arXiv2023

Concept of Inverted Refractive-Index-Contrast Grating Mirror and Exemplary Fabrication by 3D Microprinting

Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive-index-contrast grating (ICG), as compact, single layer alternative to DBR. In the ICG, a subwavelength one-dimensional grating made of a low refractive index material is implemented on a high refractive index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof-of-concept ICG fabricated according to the proposed design, using the technique of 3D microprinting in which thin stripes of IP-Dip photoresist are deposited on a Si cladding. This one-step method avoids laborious and often destructive etching-based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material.

physics.optics↗

arXiv2022

Neural networks based on ultrafast time-delayed effects in exciton-polaritons

We demonstrate that time-delayed nonlinear effects in exciton-polaritons can be used to construct neural networks where information is coded in optical pulses arriving consecutively on the sample. The highly nonlinear effects are induced by time-dependent interactions with the excitonic reservoir. These nonlinearities allow to create a nonlinear XOR logic gate that can perform operations on the picosecond timescale. An optoelectronic neural network based on the constructed logic gate performs classification of spoken digits with a high accuracy rate.

physics.optics↗

arXiv2021

Molecular Beam Epitaxy of a 2D material nearly lattice matched to a 3D substrate: $NiTe_{2}$ on $GaAs$

The lattice mismatch between interesting 2D materials and commonly available 3D substrates is one of the obstacles in the epitaxial growth of monolithic 2D/3D heterostructures, but a number of 2D materials have not yet been considered for epitaxy. Here we present the first molecular beam epitaxy growth of NiTe$_{2}$ 2D transition metal dichalcogenide. Importantly, the growth is realized on a nearly lattice matched GaAs(111)B substrate. Structural properties of the grown layers are investigated by electron diffraction, X-ray diffraction, and scanning tunnelling microscopy. Surface coverage and atomic scale order is evidenced by images obtained with atomic force, scanning electron, and transmission electron microscopy. Basic transport properties were measured confirming that NiTe$_{2}$ layers are metallic, with the Hall concentration of $10^{20}$cm$^{-3}$ to $10^{23}$cm$^{-3}$, depending on the growth conditions.

cond-mat.mtrl-sci↗

arXiv2021

Polariton lasing and energy-degenerate parametric scattering in non-resonantly driven coupled planar microcavities

Multi-level exciton-polariton systems offer an attractive platform for studies of non-linear optical phenomena. However, studies of such consequential non-linear phenomena as polariton condensation and lasing in planar microcavities have so far been limited to two-level systems, where the condensation takes place in the lowest attainable state. Here, we report non-equilibrium Bose-Einstein condensation of exciton-polaritons and low threshold, dual-wavelength polariton lasing in vertically coupled, double planar microcavities. Moreover, we find that the presence of the non-resonantly driven condensate triggers interbranch exciton-polariton transfer in the form of energy-degenerate parametric scattering. Such an effect has so far been observed only under excitation that is strictly resonant in terms of the energy and incidence angle. We describe theoretically our time-integrated and time-resolved photoluminescence investigations by a set of rate equations involving an open-dissipative Gross-Pitaevskii equation. Our platform's inherent tunability is promising for construction of planar lattices, enabling three-dimensional polariton hopping and realization of photonic devices, such as two-qubit polariton-based logic gates.

cond-mat.mes-hall↗

arXiv2020

Long-Distance Coupling and Energy Transfer between Exciton States in Magnetically Controlled Microcavities

Coupling of quantum emitters in a semiconductor relies, generally, on short-range dipole-dipole or electronic exchange type interactions. Consistently, energy transfer between exciton states, that is, electron-hole pairs bound by Coulomb interaction, is limited to distances of the order of 10~nm. Here, we demonstrate polariton-mediated coupling and energy transfer between excitonic states over a distance exceeding 2~$μ$m. We accomplish this by coupling quantum well-confined excitons through the delocalized mode of two coupled optical microcavities. Use of magnetically doped quantum wells enables us to tune the confined exciton energy by the magnetic field and in this way to control the spatial direction of the transfer. Such controlled, long-distance interaction between coherently coupled quantum emitters opens possibilities of a scalable implementation of quantum networks and quantum simulators based on solid-state, multi-cavity systems.

cond-mat.mes-hall↗

arXiv2020

Magnetoelastic interaction in the two-dimensional magnetic material MnPS$_3$ studied by first principles calculations and Raman experiments

We report experimental and theoretical studies on the magnetoelastic interactions in MnPS$_3$. Raman scattering response measured as a function of temperature shows a blue shift of the Raman active modes at 120.2 and 155.1 cm$^{-1}$, when the temperature is raised across the antiferromagnetic-paramagnetic transition. Density functional theory (DFT) calculations have been performed to estimate the effective exchange interactions and calculate the Raman active phonon modes. The calculations lead to the conclusion that the peculiar behavior with temperature of the two low energy phonon modes can be explained by the symmetry of their corresponding normal coordinates which involve the virtual modification of the super-exchange angles associated with the leading antiferromagnetic (AFM) interactions.

cond-mat.mes-hall↗

arXiv2018

Resonant excitation of infra-red emission in GaN:(Mn,Mg)

By combining experimental photoluminescence excitation spectroscopy and calculations based on density functional theory and many-body Green's functions, the most efficient excitation channels of infra-red (IR) emission from Mn-Mg$_{k}$ paramagnetic complexes stabilized in GaN:(Mn,Mg) are here identified. Moreover, a Tanabe-Sugano energy diagram for 3$d^{2}$Mn$ ^{5+}$ is reconstructed and Mn-Mg$_{3}$ are singled out as the predominant configurations responsible for the IR emission. The correlation of intensity of the individual emission lines as a function of temperature and excitation energy, allows assigning them to well defined and specific optical transitions.

cond-mat.mtrl-sci↗

arXiv2016

Effect of electron-hole separation on optical properties of individual Cd(Se,Te) Quantum Dots

Cd(Se,Te) Quantum Dots (QD) in ZnSe barrier typically exhibit a very high spectral density, which precludes investigation of single dot photoluminescence. We design, grow and study individual Cd(Se,Te)/ZnSe QDs of low spectral density of emission lines achieved by implementation of a Mn-assisted epitaxial growth. We find an unusually large variation of exciton-biexciton energy difference (3 meV $\leq$ $Δ\mathrm{E_{X-XX}}$ $\leq$ 26 meV) and of exciton radiative recombination rate in the statistics of QDs. We observe a strong correlation between the exciton-biexciton energy difference, exciton recombination rate, splitting between dark and bright exciton, and additionally the exciton fine structure splitting $δ_1$ and Landé factor. Above results indicate that values of the $δ_1$ and of the Landé factor in the studied QDs are dictated primarily by the electron and hole respective spatial shift and wavefunctions overlap, which vary from dot to dot due to a different degree of localization of electrons and holes in, respectively, CdSe and CdTe rich QD regions.

cond-mat.mes-hall↗

arXiv2014

Influence of ZnTe based distributed Bragg reflectors on the yellow range luminescence of self assembled CdTe QDs

The influence of a distributed Bragg reflector composed of ZnTe, MgTe, and MgSe superlattices on photoluminescence of self assembled CdTe quantum dots (QD) emitting in the yellow spectral range is investigated. In the case of QDs grown on a distributed Bragg reflector the photoluminescence intensity is enhanced by more than one order of magnitude, whereas the single QD lines are broadened as compared to the case of QDs grown on a ZnTe buffer. Structural and chemical analysis reveal an unintentional formation of a thin ZnSe layer induced by the growth interruption needed for the deposition of the QDs sheet. Sharp emission lines from individual quantum dots are recovered in the case of a thicker ZnTe layer grown prior to the QDs. This indicates that growth interruptions might be responsible for the QD emission line broadening.

cond-mat.mes-hall↗

arXiv2013

Manipulating Mn--Mg$_k$ cation complexes to control the charge- and spin-state of Mn in GaN

Owing to the variety of possible charge and spin states and to the different ways of coupling to the environment, paramagnetic centres in wide band-gap semiconductors and insulators exhibit a strikingly rich spectrum of properties and functionalities, exploited in commercial light emitters and proposed for applications in quantum information. Here we demonstrate, by combining synchrotron techniques with magnetic, optical and \emph{ab initio} studies, that the codoping of GaN:Mn with Mg allows to control the Mn$^{n+}$ charge and spin state in the range $3\le n\le 5$ and $2\ge S\ge 1$. According to our results, this outstanding degree of tunability arises from the formation of hitherto concealed cation complexes Mn-Mg$_k$, where the number of ligands $k$ is pre-defined by fabrication conditions. The properties of these complexes allow to extend towards the infrared the already remarkable optical capabilities of nitrides, open to solotronics functionalities, and generally represent a fresh perspective for magnetic semiconductors.

cond-mat.mtrl-sci↗