The multiferroic semiconductor GeMnTe exhibits ferroelectricity, strong Rashba spin-orbit coupling, and carrier-mediated magnetic order, making it a unique platform for exploring the interplay among electronic, structural, and magnetic degrees of freedom. In this study, we investigate the ultrafast magnetization dynamics of Ge0.85Mn0.15Te using time-resolved magneto-optical spectroscopy. By separating magnetic and nonmagnetic contributions in the transient response, we identify two distinct laser-induced magnetic phenomena, both resulting from photoinduced effective spin-orbit torque. Coherent magnetization precession arises from a laser-induced increase in hole concentration, which modifies the occupation of Rashba-split spin-locked valence band states and alters the magnetic easy axis. The transient change in magnetic ordering, observed as variations in the coercive field, is attributed to laser-induced modifications of the ferroelectric sublattice displacement, which affect the ferroelectric polarization and the associated Rashba spin-orbit interaction. While the first type of optical spin-orbit torque has already been observed in the diluted magnetic semiconductor (Ga,Mn)As, the second effect is unique to the multiferroic Rashba semiconductor (Ge,Mn)Te, opening new opportunities for all-optical manipulation of magnetic order and spin-orbit torque generation in spin-orbitronic devices.

Spin transport across interfaces is critical for spintronic devices, yet remains difficult to probe on ultrafast timescales. We use terahertz emission spectroscopy on Co|Pt heterostructures whose interface roughness is tuned through the thickness of an underlying Au buffer layer, while leaving other growth parameters unchanged. From the measured THz electric field, we extract the interface spin-current transparency ts after correcting for the changes in sample impedance and optical absorption of the stack. Surprisingly, we find that ts decreases by only approximately 30

Solving complex tasks in a modern information‐driven society requires novel materials and concepts for energy‐efficient hardware. Antiferromagnets offer a promising platform for seeking such approaches due to their exceptional features: low‐power consumption and possible high integration density are desirable for information storage and processing or applications in unconventional computing. Among antiferromagnets, CuMnAs stands out for atomic‐level scalable magnetic textures, analogue multilevel storage capability, and the magnetic state's control by a single electrical or femtosecond laser pulse. Using a pair of excitation laser pulses, this work examines functionalities of CuMnAs favorable for information processing, readily incorporating two principles of distinct characteristic timescales. Laser‐induced transient heat dynamics at sub‐nanosecond times represents the short‐term memory and causes resistance switching due to quenching into a magnetically fragmented state. This quench switching, detectable electrically from ultrashort times to hours after writing, reminisces the long‐term memory. The versatility of the principles' combination is demonstrated by antiferromagnetic in‐memory operations. Temporal latency coding is utilized to encode data from a grayscale image into sub‐nanosecond pulse delays. Applying input laser pulses of distinct amplitudes then allows for determining their relative order at 100‐ps timescales. The results open pathways for ultrafast information processing employing antiferromagnetic memory devices.

We present a method for a precise determination of magnetic anisotropy and anisotropy of quadratic magneto-optical (MO) response of thin films of ferromagnetic and ferrimagnetic materials. The method is based on measurements of a MO response for light close to the normal incidence on the sample with a fixed position. The measurement is performed for a set of orientations of an external magnetic field and a series of incident light linear polarizations beyond the standard s and p orientations. Based on the symmetry of the signal, we are able to separate the part of MO response that is even with respect to magnetization and, in turn, to exclude all non-magnetic contributions which come from imperfections of the experimental setup or from the sample itself. It is, therefore, possible to study the sample placed inside a cryostat: the polarization changes due to cryostat windows and possible strain-induced optical anisotropy of the sample are removed by the applied data processing. Thanks to this, we can perform measurements on low or elevated temperatures (from 15 to 800 K in our case), making it possible to study the behavior of magnetic materials in different magnetic phases and/or close to phase transitions. The applicability of this experimental technique was tested by measuring the low-temperature response of two samples of ferromagnetic semiconductor (Ga,Mn)As with a different Mn content at several wavelengths, which enabled us to deduce the magnetic and quadratic MO anisotropies in this material. In particular, we observed that the anisotropy of quadratic MO coefficients in (Ga,Mn)As is much weaker than that reported previously for other magnetic material systems.

This study aimed primarily at completing and extending the characterization of the crystallographic, spectroscopic and optical properties of polar, biaxial, optically negative 2-aminopyrimidinium(1+) hydrogen phosphite. Besides the redetermination of the low-temperature crystal structure (space group P21), high-quality single crystals of this salt were grown from an aqueous solution, and their optical properties were studied. The determination of the refractive indices in the wavelength range of 435-1083 nm showed anomalous dispersion of the refractive indices, resulting in a point of uniaxiality. The crystal allows phase matching for collinear second harmonic generation (SHG) processes of both type I and type II in a broad wavelength range. SHG properties were studied for powdered size-fractioned samples and oriented single-crystal cuts. The optical damage threshold experiments confirmed excellent optical resistance - at least 220 TWm-2 and 70 TWm-2 for 800 and 1000 nm irradiation, respectively. The low-temperature crystallographic study was also extended for three monoclinic salts of 2-aminopyrimidine and sulfuric acid - i.e. bis(2-aminopyrimidinium(1+) sulfate monohydrate (space group P21/n) and two polymorphs of 2-aminopyrimidinium(1+) hydrogen sulfate (both with space group P21/c). The vibrational spectra of all title compounds were assigned using single-molecule quantum chemical computations (including Potential Energy Distribution analysis) in combination with the nuclear site group analysis. Spectroscopic results concerning sulfates of 2-aminopyrimidine provided valuable reference materials for the vibrational spectroscopic study and also addressed the question of their polymorphism. An optimal computational approach employing solid-state DFT calculations has also been sought to model the vibrational spectra of 2-aminopyrimidinium (1+) hydrogen phosphite crystals.

Previous experiments in compensated magnets have demonstrated a potential for approaching the limit of fastest and least-dissipative operation of digital memory bits. However, the analog route has been virtually unexplored at (sub)ps time scales. In this paper, we report on experimental separation of heat-related and quench-switching-related resistance signal dynamics induced at room temperature by a single femtosecond-laser-pulse in memory devices from metallic antiferromagnetic CuMnAs. We show that the heat-related dynamics, on picosecond to hundreds of nanoseconds time scales, can be used as a short-term memory where information about input stimuli, represented by laser-pulses, is stored temporarily. When the quench-switching threshold is reached, information is transferred to the device variable resistance, serving as a long-term memory, with time components of 10 ms and 10 s. We also deduced 10 ps time scale as an upper estimate for a conversion of the short-lived transient temperature increase to the quench-switched metastable states.

Solving complex tasks in a modern information-driven society requires novel materials and concepts for energy-efficient hardware. Antiferromagnets offer a promising platform for seeking such approaches due to their exceptional features: low power consumption and possible high integration density are desirable for information storage and processing or applications in unconventional computing. Among antiferromagnets, CuMnAs stands out for atomic-level scalable magnetic textures, analogue multilevel storage capability, and the magnetic state's control by a single electrical or femtosecond laser pulse. Using a pair of excitation laser pulses, this work examines synaptic and neuronal functionalities of CuMnAs for information processing, readily incorporating two principles of distinct characteristic timescales. Laser-induced transient heat dynamics at sub-nanosecond times represents the short-term memory and causes resistance switching due to quenching into a magnetically fragmented state. This quench switching, detectable electrically from ultrashort times to hours after writing, reminisces the long-term memory. The versatility of the principles' combination is demonstrated by operations commonly used in neural networks. Temporal latency coding, fundamental to spiking neural networks, is utilized to encode data from a grayscale image into sub-nanosecond pulse delays. Applying input laser pulses with distinct amplitudes then allows for pulse-pattern recognition. The results open pathways for designing novel computing architectures.

Twist engineering has emerged as a powerful approach for modulating electronic properties in van der Waals heterostructures. While theoretical works have predicted the modulation of spin texture in graphene-based heterostructures by twist angle, experimental studies are lacking. Here, by performing spin precession experiments, we demonstrate tunability of the spin texture and associated spin-charge interconversion with twist angle in WSe2/graphene heterostructures. For specific twist angles, we detect a spin component radial with the electron's momentum, in addition to the standard orthogonal component. Our results show that the helicity of the spin texture can be reversed by twist angle, highlighting the critical role of the twist angle in the spin-orbit properties of WSe2/graphene heterostructures and paving the way for the development of spin-twistronic devices.

In this paper, we present spectroscopic ellipsometry measurements of five selected bulk chalcogenide glasses (Ge28Sb6Se66, Ge19Sb17Se64, Ge12Sb25Se63, Ge28Sb12Se60 and As40Se60) for broad wavelength range (0.3-15 mu m) at the temperatures from room temperature up to glass transition temperature (with reserve). Temperature dependence of bandgap energy obtained from Tauc-Lorentz oscillator together with temperature dependence of refractive index for selected wavelengths (1.55, 3.4, 7.0 and 10.6 mu m) where the studied materials are transparent are presented together with thermo-optic coefficients dEg/dT and dn/dT for these wavelengths.

Synthesis of tellurium-based materials via chemical synthesis is usually based on the reduction of the tellurium source (for example Na2TeO3 or TeCl4) [1] together with (semi) metallic source (GeI2 or SnCl2) [2] at the elevated temperatures (above 150 degrees C) for several hours. There are also reports showing that similar procedure in the presence of second metallic source (for example InCl3, In(NO3)(3)) or even the metallic nanoparticles (NPs) may provide doped telluride materials [3]. The presence of NPs with various diameters gives the possibility to control the dimensions of nanostructures of tellurium-based materials [4]. Nanoparticles can offer an alternative approach to fabricate phase change materials. Contrary, the reports of chemical synthesis at room temperatures are in fact unknown. The aim of this work is preparation of GeTe nanoparticles by low temperature synthetic method exploiting new organometallic precursors. The characterization of prepared nanomaterial was performed on the basis of X-ray diffraction, transmission electron microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy, laser ablation time-of-flight (LA TOF) mass spectrometry (MS), Raman scattering spectroscopy and dynamic light scattering.

Antiferromagnetic CuMnAs thin films have attracted attention since the discovery of the manipulation of their magnetic structure via electrical, optical, and terahertz pulses, enabling convenient approaches for switching between magnetoresistive states of the film for information storage. However, the magnetic structure and, thus, the efficiency of the manipulation can be affected by the film morphology and growth defects. In this study, the properties of CuMnAs thin films are investigated by probing the asymmetrical growth‐related uniaxial anisotropy of electric conductivity by contact‐free terahertz transmission spectroscopy. It is shown that the terahertz measurements conveniently detect the conductivity anisotropy that is consistent with conventional DC Hall‐bar measurements. Moreover, the terahertz technique allows for considerably finer determination of anisotropy axes, and it is less sensitive to the local film degradation. Thanks to the averaging over a large detection area, the THz probing also allows an analysis of strongly non‐uniform thin films. Using scanning electron and near‐field terahertz microscopies, the observed anisotropic conductivity of CuMnAs is related to the elongation and orientation of growth defects, which both originate in the anisotropic growth of the films. In addition, control over the morphology of defects is demonstrated by using vicinal substrates.

In the context of the major problems linked to global warming and pollution, a micro-sensor based on mid-infrared spectroscopy could be a useful tool for the continuous measurement of various bio-chemical species that are disrupting our environment. With the aim of developing a mid-infrared source potentially integrated into a micro-sensor, we have fabricated rare-earth-doped chalcogenide thin films using various physical vapor deposition techniques [1]. Rare-earth-doped amorphous chalcogenide films play a motivating role in the development of integrated planar optical circuits. Initially, amorphous Ga-Ge-Sb-S sulfide thin films doped with dysprosium or thulium were prepared by pulsed laser deposition and radio-frequency magnetron sputtering, respectively. The results revealed promising prospects, reinforced by the clear observation of near-infrared photo-luminescence of $\mathrm{Dy}^{3+}$ and $\mathrm{Tm}^{3+}$ doped sulfide films. RF magnetron sputtering and pulsed laser deposition were then studied in the case of Erbium doping in order to optimize deposition parameters, showing near-IR and mid-IR emissions at $1.55 \ \mu \mathrm{m}\left({ }^{4} \mathrm{I}_{13 / 2} \rightarrow{ }^{4} \mathrm{I}_{15 / 2}\right)$ and at $2.8 \ \mu \mathrm{m}\left({ }^{4} \mathrm{I}_{11 / 2} \rightarrow{ }^{4} \mathrm{I}_{13 / 2}\right)$. Finally, in view of these initial mid-IR results, selenide thin films doped with praseodymium or dysprosium were deposited by radio-frequency (RF) magnetron sputtering in an attempt to luminesce further into the mid-IR. Mid-IR guided photoluminescence of $\mathrm{Dy}^{3+}$ or $\mathrm{Pr}^{3+}$ at wavelengths up to $5.5 \ \mu \mathrm{m}$ was first demonstrated at room temperature using co-propagating pumping at near-IR wavelengths for ridge structures displaying single-mode propagation at mid-IR wavelengths [2]. The luminescence properties of the waveguides are then studied as a function of rare-earth concentration and Ar pressure. In addition to the Ga-Ge-Sb-Se host matrix, the In-Ge-Sb-Se matrix has also been successfully studied. Based on this on-chip emission, CO 2 detection around $4.3 \ \mu \mathrm{m}$ has also been performed

Organometallic positive ions were identified in inductively coupled plasmas by means of mass spectrometry during the etching of Ge, Sb, Se materials. A preliminary study was focused on identifying M x H y + (M = Ge, Sb, Se) positive ion clusters during a H 2 /Ar etching process. The methane addition to the H 2 /Ar mixture generates CH x reactive neutral species. The latter react with the metalloids within gas phase to form M x C y H z + organometallic ions. In addition, the etching of Sb 2 Se 3 and Ge 19.5 Sb 17.8 Se 62.7 bulk targets forms mixed products via ion-molecule reactions as evidenced by the presence of SeSbC x H y + ion clusters. Changes in surface composition induced by the newly formed organometallic structures were investigated using in situ x-ray photoelectron spectroscopy. In the case of the Ge and Sb surfaces, (M)–M–C x environments broadened the Ge 2p 3/2 , Ge 3d, Sb 3d and Sb 4d spectra to higher values of binding energy. For the Se surface, only the hydrogen and methyl bonding could explain the important broadening of the Se 3d core level. It was found that the Ge 39 Se 61 thin film presents an induced (Ge)–Ge–Se entity on the Ge 2p 3/2 and Ge 3d core levels.

The observation of a sizable anomalous Hall effect in magnetic materials with vanishing magnetization has renewed interest in understanding and engineering this phenomenon. Antiferromagnetic antiperovskites are one of emerging material classes that exhibit a variety of interesting properties owing to a complex electronic band structure and magnetic ordering. Reports on the anomalous Nernst effect and its magnitude in this class of materials are, however, very limited. This scarcity may be partly due to the experimental difficulty of reliably quantifying the anomalous Nernst coefficient. Here, we report experiments on the anomalous Nernst effect in antiferromagnetic antiperovskite Mn$_3$NiN thin films. Measurement of both the anomalous Hall and Nernst effects using the same sample and measurement geometry makes it possible to directly compare these two effects and quantify the anomalous Nernst coefficient and conductivity in Mn$_3$NiN. We carefully evaluate the spatial distribution of the thermal gradient in the sample and use finite element modeling to corroborate our experimental results.

In the search for new molecular crystals for nonlinear optics (NLO), nine inorganic salts containing the 1,3diaminoguanidinium(1+) cation as a promising organic "Y-aromatic" carrier of NLO properties were prepared and studied. Crystal structures of eight new salts, namely 1,3-diaminoguanidinium(1+) chloride (P2(1)/c), hypophosphite (P2(1)/c), hydrogen phosphite (P-1), dihydrogen phosphate (P21/c), hydrogen phosphate (P2(1)/m), nitrite (P-1), sulfite (Pbcm) and chlorate (P2(1)/c) were solved by the single crystal X-ray diffraction. The crystal structures contain centrosymmetric arrangements of pairs of counterions assembled into hydrogen-bonded undulated sheets. The charge-assisted hydrogen bonds in the resulting hydrogen bond networks are accommodated by the conformation of the 1,3-diaminoguanidinium(1+) cation as a hydrogen bond donor. All salts were also characterized by powder X-ray diffraction. The vibrational spectra (FTIR and Raman) were studied for all newly prepared salts and the previously published non-centrosymmetric sulfate (P6(1)22). The assignment of the vibrational bands of these hydrogen-bonded crystals is derived from quantum-chemical computations (B3LYP/6311G+(d,p) along with the Potential Energy Distribution analysis) concerning isolated 1,3-diaminoguanidinium (1+) cation and the results of correlation analysis involving present inorganic anions. The linear and nonlinear optical properties of the only non-centrosymmetric salt - 1,3-diaminoguanidinium sulfate - were studied. This uniaxial positive crystal is optically transparent down to 230 nm, and refractive indices (n(e) = 1.65 and no = 1.56) have been determined at 532 nm. The dispersion curves of the refractive indices were also calculated by the Q (LFT) procedure in the 532-1907 nm region. The experimentally determined (using 800 and 1000 nm laser irradiation) very low efficiency of second harmonic generation (i.e., similar to 1% of KDP), which is consistent with the Kleinman symmetry assumption for the P6(1)22 space group, limits further use of this crystal for second-order NLO applications.

Large single crystals of polar tetragonal thallium antimony(III) tartrate dihydrate, Tl 2 [Sb 2 ( (+) C 4 H 2 O 6 ) 2 ]·2H 2 O, are grown. The crystal structure (s.g. P 4 1 ), which contains the binuclear complex group [Sb 2 (C 4 H 2 O 6 ) 2 ] 2− and dimer groups [Tl 2 O 8 (H 2 O) 2 ], is given, together with vibrational spectra, refractive indices and their dispersion, and an analysis of SHG phase matching possibility and SHG powder measurements. The crystals allow type I phase matching for laser wavelengths ≥ 1.0103 µm. In addition, a new monoclinic (s.g. C 2) antimony(III) tartrate of composition Mg[Sb 3 ( (+) C 4 H 2 O 6 ) 2 ( (+) C 4 H 4 O 6 )( (+) C 4 H 5 O 6 )]·11H 2 O and its crystal structure, which contains a novel type of antimony tartrate complex group [Sb 3 (C 4 H 2 O 6 ) 2 (C 4 H 4 O 6 )(C 4 H 5 O 6 )], is presented.

All-optical ferromagnetic resonance (AO-FMR) is a powerful tool for the local detection of micromagnetic parameters, such as magnetic anisotropy, Gilbert damping or spin stiffness. In this work we demonstrate that the AO-FMR method can be used in thin films of yttrium iron garnet (YIG) if a metallic capping layer (Au, Pt) is deposited on top of the film. Magnetization precession is triggered by heating of the metallic layer with femtosecond laser pulses. The heat pulse modifies the magneto-crystalline anisotropy of the YIG film and shifts the quasi-equilibrium orientation of the magnetization, which results in precessional magnetization dynamics. The laser-induced magnetization precession corresponds to a uniform (Kittel) magnon mode, with the precession frequency determined by the magnetic anisotropy of the material as well as the external magnetic field, and the damping time set by a Gilbert damping parameter. The AO-FMR method thus enables measuring local magnetic properties, with a resolution given by the laser spot size.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Quenching of CuMnAs was recently discovered using electrical and train of optical pulses. In this contribution, we report the single laser pulse quench switching and erasing using different pulse parameters to improve the response.

To realize the very objective of spintronics, namely the development of ultra-high frequency and energy-efficient electronic devices, an ultrafast and scalable approach to switch magnetic bits is required. Magnetization switching with spin currents generated by the spin-orbit interaction at ferromagnetic/non-magnetic interfaces is one of such scalable approaches, where the ultimate switching speed is limited by the Larmor precession frequency. Understanding the magnetization precession dynamics induced by spin-orbit torques (SOTs) is therefore of great importance. Here we demonstrate generation of ultrashort SOT pulses that excite Larmor precession at an epitaxial Fe/GaAs interface by converting femtosecond laser pulses into high-amplitude current pulses in an electrically biased p-i-n photodiode. We control the polarity, amplitude, and duration of the current pulses and, most importantly, also their propagation direction with respect to the crystal orientation. The SOT origin of the excited Larmor precession was revealed by a detailed analysis of the precession phase and amplitude at different experimental conditions.