Lukas M Eng

Lukas M Eng
Technische Universität Dresden | TUD

About

264
Publications
30,514
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
6,379
Citations

Publications

Publications (264)
Article
Full-text available
Novel devices based on ferroelectric hafnium oxide comply with the increasing demand for highly scalable embedded non-volatile memory devices, especially for in-memory computing applications. However, due to the polycrystalline nature of these hafnium oxide films, highly scaled devices face variability concerns. In order to enable smaller grains to...
Article
A conceptually new approach to synchronizing accelerator-based light sources and external laser systems is presented. The concept is based on utilizing a sufficiently intense accelerator-based single-cycle terahertz pulse to slice a thereby intrinsically synchronized femtosecond-level part of a longer picosecond laser pulse in an electro-optic crys...
Article
Strongly charged head-to-head domain walls that are purposely engineered along the [110] crystallographic orientation into ferroelectric BaTiO3 single crystals have been proposed as intrinsically nanoscaled two-dimensional electron gases (2DEGs) because of their significant conductivity. Here, we quantify these 2DEG properties through dedicated Hal...
Preprint
Ferroelectric domain boundaries are quasi-two-dimensional functional interfaces with high prospects for nanoelectronic applications. Despite their reduced dimensionality, they can exhibit complex non-Ising polarization configurations and unexpected physical properties. Here, the impact of the three-dimensional (3D) curvature on the polarization pro...
Article
Pure samples of colorless, air‐stable Ba(BO 2 OH) crystals were obtained from Ba(NO 3 ) 2 and H 3 BO 3 under the ultra‐alkaline conditions of a KOH hydroflux at about 250 °C. The product formation depends on the water‐base molar ratio and the molar ratio of the starting materials. B(OH) 3 acts as a proton donor (Brønsted acid) rather than a hydroxi...
Article
Full-text available
Recent analyses by polarization resolved second-harmonic (SH) microscopy have demonstrated that ferroelectric (FE) domain walls (DWs) can possess non-Ising wall characteristics and topological nature. These analyses rely on locally analyzing the properties, directionality, and magnitude of the second-order nonlinear tensor. However, when inspecting...
Preprint
Full-text available
Conductive domain walls (CDWs) in insulating ferroelectrics have recently attracted considerable attention due to their unique topological, optical, and electronic properties, and offer potential applications such as in memory devices or re-writable circuitry. The electronic properties of domain walls (DWs) can be tuned by the application of strain...
Preprint
Full-text available
Strongly charged head-to-head (H2H) domain walls (DWs) that are purposely engineered along the [110] crystallographic orientation into ferroelectric BaTiO$_3$ single crystals have been proposed as novel 2-dimensional electron gases (2DEGs) due to their significant domain wall conductivity (DWC). Here, we quantify these 2DEG properties through dedic...
Article
Full-text available
Spontaneous Raman spectroscopy (SR) is a versatile method for analysis and visualization of ferroelectric crystal structures, including domain walls. Nevertheless, the necessary acquisition time makes SR impractical for in situ analysis and large scale imaging. In this work, we introduce broadband coherent anti-Stokes Raman spectroscopy (B-CARS) as...
Conference Paper
Hafnium oxide-based ferroelectric tunnel junctions (FTJs) are novel nonvolatile memory devices with promising advantages such as non-destructive readout in comparison to conventional ferroelectric random access memories (FRAMs). Reliability aspects of FTJ devices need to be investigated, including their endurance, retention, ferroelectric switching...
Article
Full-text available
Recently, ferroelectric domain walls (DWs) have attracted considerable attention due to their intrinsic topological effects and their huge potential for optoelectronic applications. In contrast, many of the underlying physical properties and phenomena are not well characterized. In this regard, analyzing the vibrational properties, e.g. by Raman sp...
Article
Broadband coherent anti-Stokes Raman scattering (B-CARS) has emerged in recent years as a promising chemosensitive high-speed imaging technique. B-CARS allows for the detection of vibrational sample properties in analogy to spontaneous Raman spectroscopy, but also makes electronic sample environments accessible due to its resonant excitation mechan...
Article
Nonvolatile memories especially the ferroelectric (FE)-based ones such as ferroelectric tunnel junctions (FTJs) and ferroelectric field-effect transistors (FeFETs) have recently attracted a lot of attention. FTJs have been intensively researched for the last decade and found to be very promising memory devices due to their significant nondestructiv...
Article
Full-text available
Ferroelectricity in crystalline hafnium oxide thin films is strongly investigated for the application in non-volatile memories, sensors and other applications. Especially for back-end-of-line (BEoL) integration the decrease of crystallization temperature is of major importance. However, an alternative method for inducing ferroelectricity in amorpho...
Preprint
Full-text available
Skyrmionics materials hold the potential for future information technologies, such as racetrack memories. Key to that advancement are skyrmionics systems that exhibit high tunability and scalability, with stored information being easy to read and write by means of all-electrical techniques. Topological magnetic excitations, such as skyrmions and an...
Article
Full-text available
Non-volatile memories based on ferroelectric hafnium oxide, especially the ferroelectric field-effect transistor (FeFET), have outstanding properties, e.g. for the application in neuromorphic circuits. However, material development has focused so far mainly on metal–ferroelectric–metal (MFM) capacitors, while FeFETs are based on metal–ferroelectric...
Preprint
Terahertz (THz) electromagnetic radiation is key to optically access collective excitations such as magnons (spins), plasmons (electrons), or phonons (atomic vibrations), thus bridging between optics and solid-state physics. Confinement of THz light to the nanometer length scale is desirable for local probing of such excitations in low dimensional...
Article
Chalcogenide phase change materials reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. However, a fundamental understanding of their laser-switching behavior is lacking and the resulting local optical properties are unclear at the nanoscale. Here, we combine infrared s...
Article
Full-text available
Domain walls (DWs) in ferroelectric (FE) and multiferroic materials possess an ever-growing potential as integrated functional elements, for instance in optoelectronic nanodevices. Mandatory, however, is the profound knowledge of the local-scale electronic and optical properties, especially at DWs that are still incompletely characterized to date....
Article
Full-text available
Thin-film lithium niobate (TFLN) in the form of x- or z-cut lithium-niobate-on-insulator has attracted considerable interest as a very promising and novel platform for developing integrated optoelectronic (nano)devices and exploring fundamental research. Here, we investigate the coherent interaction length lc of optical second-harmonic generation (...
Conference Paper
Hafnium oxide based ferroelectric FETs (FeFETs) are highly suitable for in-memory computing applications like neuromorphic hardware due to their CMOS compatibility, high dynamic range, low power consumption and good linearity. Device-to-device and die-to-die variability play an important role, especially due to the polycrystalline nature of ferroel...
Preprint
Full-text available
Thin-film lithium niobate (TFLN) in the form of x- or z-cut lithium-niobate-on-insulator (LNOI) has recently popped up as a very promising and novel platform for developing integrated optoelectronic (nano)devices and exploring fundamental research. Here, we investigate the coherent interaction length $l_{c}$ of optical second-harmonic (SH) microsco...
Article
Full-text available
The discovery of ferroelectricity in the fluorite structure based hafnium oxide (HfO2) material sparked major efforts for reviving the ferroelectric field effect transistor (FeFET) memory concept. A Novel metal-ferroelectric-metal-ferroelectric-insulator-semiconductor (MFMFIS) FeFET memory is reported based on dual ferroelectric integration as an M...
Article
Full-text available
In the last two decades, variably doped strontium barium niobate (SBN) has attracted a lot of scientific interest mainly due to its specific non-linear optical response. Comparably, the parental compound, i.e., undoped SBN, appears to be less studied so far. Here, two different cuts of single-crystalline nominally pure strontium barium niobate in t...
Article
Full-text available
Orange‐colored crystals of the oxoferrate tellurate K 12+6x Fe 6 Te 4–x O 27 [ x = 0.222(4)] were synthesized in a potassium hydroxide hydroflux with a molar water‐base ratio n (H 2 O) : n (KOH) = 1.5 starting from Fe(NO 3 ) 3 ·9H 2 O, TeO 2 and H 2 O 2 at about 200 °C. By using (NH 4 ) 2 TeO 4 instead of TeO 2 , a fine powder consisting of microcr...
Article
Full-text available
The hafnium oxide material class is characterized by the coexistence of several polymorphs between which phase transitions are induced by means of composition and external electric fields. Pyroelectric materials, which convert heat into electrical energy, exhibit the largest response at such morphotropic or field-induced phase transitions. The hafn...
Cover Page
Full-text available
With the help of transmission Kikuchi diffraction the major physical mechanism of antiferroelectric-like behavior as well as of the wake-up effect is determined by Maximilian Lederer, Konrad Seidel, and co-workers in article number 2100086. Furthermore, guidelines on how to influence this behavior by crystallographic texture and adjacent layers, as...
Article
Full-text available
Infrared nano-spectroscopy based on scattering-type scanning near-field optical microscopy (s-SNOM) is commonly employed to probe the vibrational fingerprints of materials at the nanometer length scale. However, due to the elongated and axisymmetric tip shank, s-SNOM is less sensitive to the in-plane sample anisotropy in general. In this article, w...
Article
Full-text available
Die elektronenreichen Cyanidometallate [Fe(CN)3]⁷⁻ und [Ru(CN)3]⁷⁻ enthalten erstmals Elemente der Gruppe 8 in der Oxidationsstufe −IV. DFT-Berechnungen ergeben eine nominelle d¹⁰s⁰-Konfiguration der Zentralatome, die einer effektiven Ladung von 2− entspricht. Die hohe Ladung schwächt die C-N-Bindungen durch die Besetzung von antibindenden Zustände...
Article
Full-text available
Exceptionally electron‐rich, nearly trigonal‐planar tricyanidometalate anions [Fe(CN)3]7– and [Ru(CN)3]7– were stabilized in LiSr3[Fe(CN)3] and Ae3.5M(CN)3] (Ae = Sr, Ba; M = Fe, Ru). They are the first examples of group 8 elements with the oxidation state of –IV. Microcrystalline powders were obtained by a solid‐state route, single‐crystals from a...
Article
Full-text available
Ferroelectric hafnium oxide (HfO2) is considered as a very prospective material for applications in integrated devices, due to its considerably large spontaneous polarization and superior thickness scaling. In fact, the evolution of the ferroelectric hysteresis upon field cycling plays the important role in most applications; especially the so‐call...
Article
Full-text available
Hyperbolic phonon polaritons have recently attracted considerable attention in nanophotonics mostly due to their intrinsic strong electromagnetic field confinement, ultraslow polariton group velocities, and long lifetimes. Here we introduce tin oxide (SnO2) nanobelts as a photonic platform for the transport of surface and volume phonon polaritons i...
Preprint
Full-text available
Mn1.4PtSn is the first material in which antiskyrmions have been observed in ultra-thin single crystalline specimens. While bulk crystals exhibit fractal patterns of purely ferromagnetic domain ordering at room temperature, ultra-thin Mn1.4PtSn lamellae clearly show antiskyrmion lattices with lattice spacings up to several $\mu$m. In the work prese...
Preprint
Full-text available
In the cubic chiral magnet Fe$_{1-x}$Co$_{x}$Si a metastable state comprising of topologically nontrivial spin whirls, so-called skyrmions, may be preserved down to low temperatures by means of field cooling the sample. This metastable skyrmion state is energetically separated from the topologically trivial ground state by a considerable potential...
Preprint
Full-text available
Cu$_2$OSeO$_3$ is an insulating skyrmion-host material with a magnetoelectric coupling giving rise to an electric polarization with a characteristic dependence on the magnetic field $\vec H$. We report magnetic force microscopy imaging of the helical real-space spin structure on the surface of a bulk single crystal of Cu$_2$OSeO$_3$. In the presenc...
Article
Full-text available
Nonlinear and quantum optical devices based on periodically-poled thin film lithium niobate (PP-TFLN) have gained considerable interest lately, due to their significantly improved performance as compared to their bulk counterparts. Nevertheless, performance parameters such as conversion efficiency, minimum pump power, and spectral bandwidth strongl...
Article
Full-text available
The hafnium oxide (HfO2) material system offers a unique combination of outstanding physical properties, that enable a manifold of novel integrated ferroelectric, piezoelectric, and pyroelectric applications. Long‐term stability is an essential concern for non‐volatile memory devices, sensors, and nano‐electromechanical systems (NEMS). Here, we rep...
Article
A novel hybrid antiferroelectric (AFE)-based charge trap (CT) memory is reported focusing on an amplified tunnel oxide field (ETO) via the dynamic of an AFE hysteresis dipole switching. The role of dynamic permittivity increase and the saturated polarization at the instant of the write operation are explored for enhanced ETO. The hybrid CT concept...
Article
Full-text available
Electromagnetic field confinement is crucial for nanophotonic technologies, since it allows for enhancing light–matter interactions, thus enabling light manipulation in deep sub‐wavelength scales. In the terahertz (THz) spectral range, radiation confinement is conventionally achieved with specially designed metallic structures—such as antennas or n...
Preprint
Full-text available
Local-probe imaging of the ferroelectric domain structure and auxiliary bulk pyroelectric measurements were conducted at low temperatures with the aim to clarify the essential aspects of the orbitally driven phase transition in GaMo4S8, a lacunar spinel crystal that can be viewed as a spin-hole analogue of its GaV4S8 counterpart. We employed multip...
Article
Full-text available
Applying transmission Kikuchi diffraction (TKD) allows us to fundamentally investigate the Si-doped-hafnium-oxide (HSO) microstructure that results from the interface layer present in ferroelectric field-effect transistors. In addition to the predominant orthorhombic phase, dendritic HSO grains larger than 100 nm govern the microstructure compositi...
Conference Paper
We apply broadband coherent anti-Stokes Raman scattering, an imaging tech- nique mostly applied in biology, to the solid state system lithium niobate, where we show an enhanced full spectrum and a working signal transformation.
Conference Paper
The influence of geometrical confinement in back-reflection Second-Harmonic microscopy is experimentally and theoretically investigated in the wedge-shaped model system lithium niobate. The co-propagating signal is found to be the dominating contribution.
Conference Paper
Full-text available
We demonstrate the feasibility of thermal energy recovery in the back end of line (BEoL) employing CMOS-compatible ferroelectric hafnium oxide. Efficient pyroelectric energy harvesting with a sizable power density of 92 mWcm-3 under typical thermal conditions is achieved. Our energy harvesting approach exceeds the efficiency limit of commonly-used...
Conference Paper
Full-text available
We report on antiferroelectric (AFE) hybrid charge trap (CT) memory with amplified tunnel oxide field via dynamic AFE hysteresis dipole switching. Memory window (4.5V), switching speed (<1μs), 10 years retention, and 10^5 endurance are reported. The HSO/HZO with tailored (FE,AFE) hysteresis are explored for low power and high-speed-boosted CT memor...
Article
Full-text available
Optical activation of material properties illustrates the potentials held by tuning light-matter interactions with impacts ranging from basic science to technological applications. Here, we demonstrate for the first time that composite nanostructures providing nonlocal environments can be engineered to optically trigger photoinduced charge-transfer...
Article
Local electric fields play the key role in near-field optical examinations and are especially appealing when exploring heterogeneous or even anisotropic nano-systems. Scattering-type near-field optical microscopy (s-SNOM) is the most commonly used method applied to explore and quantify such confined electric fields at the nanometer length scale: wh...
Article
Full-text available
A strongly temperature-dependent photo-induced transient absorption is measured in 6.5 mol% magnesium-doped lithium niobate at temperatures ranging from 45 K to 225 K. This phenomenon is interpreted as resulting from the generation and subsequent recombination of oppositely charged small polarons. Initial two-photon absorptions generate separated o...
Article
Full-text available
Ferroelectric domain wall conductance is a rapidly growing field. Thin-film lithium niobate, as in lithium niobate on insulators (LNOI), appears to be an ideal template, which is tuned by the inclination of the domain wall. Thus, the precise tuning of domain wall inclination with the applied voltage can be used in non-volatile memories, which store...
Article
Full-text available
The accurate determination of electrocaloric coefficients in nanometer-thin, polycrystalline doped HfO2 is challenging and has led to very different values reported in the literature. Here, we apply two different methods in order to compare and analyze reversible and irreversible or metastable contributions to the electrocaloric effect. The indirec...
Conference Paper
Full-text available
Ferroelectric domain wall conductance is a rapidly growing field, apparently for inclined domain walls. In this study we present thin-film lithium niobate as an ideal template, in which the inclination of the domain wall can be tuned and hence, the conductance. The precise tuning of domain wall inclination upon an applied voltage is hereby interest...
Conference Paper
Full-text available
Nanoelectronic devices based on ferroelectric domain walls (DWs), have attracted interest in the recent years. Practical high-speed electronics, usually demand operation frequencies in the gigahertz (GHz) regime, where the effect of dipolar oscillation is important. In this study we observe an unexpected giant GHz conductivity on the order of 10 2...
Article
Cu2OSeO3 is an insulating skyrmion-host material with a magnetoelectric coupling giving rise to an electric polarization with a characteristic dependence on the magnetic-field H⃗. We report a magnetic force microscopy imaging of the helical real-space spin structure on the surface of a bulk single crystal of Cu2OSeO3. In the presence of a magnetic...
Article
Full-text available
Cu 2 OSeO 3 is an insulating skyrmion-host material with a magnetoelectric coupling giving rise to an electric polarization with a characteristic dependence on the magnetic-field H. We report a magnetic force microscopy imaging of the helical real-space spin structure on the surface of a bulk single crystal of Cu 2 OSeO 3. In the presence of a magn...
Preprint
Electromagnetic field confinement is crucial for nanophotonic technologies, since it allows for enhancing light-matter interactions, thus enabling light manipulation in deep sub-wavelength scales. In the terahertz (THz) spectral range, radiation confinement is conventionally achieved with specially designed metallic structures - such as antennas or...
Article
Full-text available
We report a magnetic state in GaV4Se8 which emerges exclusively in samples with mesoscale polar domains and not in polar mono-domain crystals. It is manifested by a sharp anomaly in the magnetic susceptibility and the magnetic torque, distinct from other anomalies observed also in polar mono-domain samples upon transitions between the cycloidal, th...
Article
Full-text available
Plasma waves play an important role in many solid-state phenomena and devices. They also become significant in electronic device structures as the operation frequencies of these devices increase. A prominent example is field-effect transistors (FETs), that witness increased attention for application as rectifying detectors and mixers of electromagn...
Article
Optical second harmonic generation (SHG) at surfaces and interfaces is an exciting new technique. In order to achieve high surface specificity and sensitivity of the SHG technique, smaller particles of SHG materials are highly desired. Borate halides are regarded as a great source of SHG materials because of their outstanding non‐linear optical pro...