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Current-induced field-free magnetic switching using spin–orbit torque has been an important topic for decades due to both academic and industrial interest. Most research has focused on introducing symmetry breakers, such as geometrical and compositional variation, pinned layers, and symmetry-broken crystal structures, which add complexity to the magnetic structure and fabrication process. We designed a relatively simple magnetic structure, composed of a [Co/Pt] multilayer and a Co layer with perpendicular and in-plane magnetic anisotropy, respectively, with a Cu layer between them. Current-induced deterministic magnetic switching was observed in this magnetic system. The system is advantageous due to its easy control of the parameters to achieve the optimal condition for magnetic switching. The balance between magnetic anisotropic strength and interlayer coupling strength is found to provide the optimal condition. This simple design and easy adjustability open various possibilities for magnetic structures in spin-based electronics applications using spin–orbit torque. [ABSTRACT FROM AUTHOR]

We report an isothermal electric field-induced first-order phase transition from a Mott insulator to the metallic state in the epitaxial thin film of V 2 O 3 in the temperature regime below its Mott transition temperature of ≈ 180 K. This isothermal electric field-induced transition is accompanied by interesting electrothermal history effects, which depend on the measurement paths followed in the electric field–temperature phase space. These interesting properties result in tuneable resistive switching and distinct memristive behaviour in V 2 O 3 . A generalized framework of disorder-influenced first-order phase transition in combination with a resistor network model has been used to explain the observed experimental features. These findings promise possibilities for Mott insulators to be used as highly energy-efficient switches in novel technologies such as neuromorphic computing. [ABSTRACT FROM AUTHOR]

LaFeO3 thin films were successfully epitaxially grown on single-crystalline SrTiO3 substrates by the one-step hydrothermal method at a temperature of 320 °C in a 10 mol/L KOH aqueous solution using La(NO3)3 and Fe(NO3)3 as the raw materials. The growth of the films was consistent with the island growth mode. Scanning electronic microscopy, elemental mapping, and atomic force microscopy demonstrate that the LaFeO3 thin films cover the SrTiO3 substrate thoroughly. The film subjected to hydrothermal treatment for 4 h exhibits a relatively smooth surface, with an average surface roughness of 10.1 nm. X-ray diffraction in conventional Bragg–Brentano mode shows that the LaFeO3 thin films show the same out-of-plane orientation as that of the substrate (i.e., (001)LaFeO3||(001)SrTiO3). The in-plane orientation of the films was analyzed by φ-scanning, revealing that the orientational relationship is [001]LaFeO3||[001]SrTiO3. The ω-rocking curve indicates that the prepared LaFeO3 films are of high quality with no significant mosaic defects. [ABSTRACT FROM AUTHOR]

This study reports on the magnetic hardening phenomenon of heavily helium ion-irradiated iron–chromium alloys. The alloys are important structural materials in next-generation nuclear reactors. In some cases, problems may arise when the magnetic properties of the materials change due to neutron irradiation. Therefore, it is necessary to understand the effects of irradiation on magnetism. Helium irradiation was conducted as a simulated irradiation, and the effect of cavity formation on magnetic properties was thoroughly investigated. High-quality single-crystal Fe-x%Cr (x = 0, 10, 20) films, with a thickness of 180–200 nm, were fabricated through ultra-high vacuum evaporation. Subsequently, irradiation of 19 dpa with 30 keV He+ ions was conducted at room temperature. X-ray diffraction measurements and electron microscopy observations confirmed significant lattice expansion and the formation of high-density cavities after irradiation. The magnetization curve of pure iron remained unchanged, while magnetic hardening was noticed in iron–chromium alloys. This phenomenon is believed to be due to the combined effect of cavity formation and changes in the atomic arrangement of chromium. [ABSTRACT FROM AUTHOR]

Abstract Nanotwinned metals have been intensely investigated due to their unique microstructures and superior properties. This work aims to investigate the nanovoid formation mechanism in sputter-deposited nanotwinned Cu. Three different types of epitaxial or polycrystalline Cu films are fabricated by magnetron sputtering deposition technique. In the epitaxial Cu (111) films deposited on Si (110) substrates, high fractions of nanovoids and nanotwins are formed. The void size and density can be tailored by varying deposition parameters, including argon pressure, deposition rate, and film thickness. Interestingly, nanovoids become absent in the polycrystalline Cu film deposited on Si (111) substrate, but they can be regained in the epitaxial nanotwinned Cu (111) when deposited on Si (111) substrate with an Ag seed layer. The nanovoid formation seems to be closely associated with twin nucleation and film texture. Based on the comparative studies between void-free polycrystalline Cu films and epitaxial nanotwinned Cu films with nanovoids, the underlying mechanisms for the formation of nanovoids are discussed within the framework of island coalescence model. Graphical abstract

In this paper, β -(Al x Ga 1-x) 2 O 3 heteroepitaxial films with different Al content were successfully prepared on p-GaN substrates by MOCVD method. When the "x" values are in a range of 0–0.38, the (Al x Ga 1-x) 2 O 3 grown on p-GaN is an epitaxial film, maintaining the lattice structure of β -Ga 2 O 3 , and presenting an adjustable bandgap of 5.0–5.93 eV. When x = 0.45, the film is amorphous, and present a low bandgap of ∼5.73 eV due to the band tail formed by a large number of defects. φ scanning, HRTEM and SAED results showed that the prepared film was a six-fold domain structure and had an epitaxial relationship with the substrate of β -(Al x Ga 1-x) 2 O 3 (2 ‾ 01) || GaN (0001) with β -(Al x Ga 1-x) 2 O 3 [102] || GaN <1-100>. The photodetector (PD) based on β -(Al x Ga 1-x) 2 O 3 /GaN p-n junction presents high photoresponsivity (0.045 A/W) at 218 nm. The wavelength is far lower than the optimal responsive wavelength (254 nm) of β -Ga 2 O 3 in previous reports, meaning that β -(Al x Ga 1-x) 2 O 3 can be used to fabricate shorter wavelength UV photodetector. [ABSTRACT FROM AUTHOR]

During cooling, conventional martensitic transformation can only be realized from austenite to martensite. Recently, a so-called reentrant martensitic transformation attracted much interest due to an additional transformation from martensite to austenite during further cooling. Obviously, materials with this reentrant transformation will increase the number of physical effects and possible applications. However, until now, only bulk samples have been available, which are not suitable for applications in micro-devices. In this work, we focus on the Co-Cr-Ga-Si system and examine the suitability of this system for the growth of thin films. We observed that the films grow epitaxially on MgO (100) substrates and exhibit a martensitic transformation if deposited at a sufficiently high temperature or with an additional heat treatment. Films within the austenite state are ferromagnetic while films within the martensitic state just exhibit a very low ferromagnetic order. We sincerely make a statement that our work is arranged in the scientific way with highly novelty. So far, the research and reports on reentrant martensitic materials are very less. We make a starting in thin films to arouse enthusiasm for research on this novel shape memory materials. Although we could not observe a reentrant martensitic transformation in the additional experiments due to the limited conditions, we consider our work as a substantial advance in science since we present for the first time a route to prepare epitaxial films from this emerging material, which allowed analyzing its functional properties. So, we think our work is at the high novelty. We consider our manuscript relevant for the broad interdisciplinary readership of Science and Technology of Advanced Materials. First, it is relevant for material scientists, as it addresses reentrant martensite as an emerging class of functional materials. Second, it is interesting for physicist, as our epitaxial films enable probing the underlying mechanism driving a reentrant transition. Third, it is interesting for engineers, as reentrant films are required for microsystems based on this multifunctional material. We thank you for your consideration and your time. We hope that our work is now acceptable for publication in Science and Technology of Advanced Materials. [ABSTRACT FROM AUTHOR]

This study reports on the microstructure and magnetism of pure iron irradiated with high doses of helium ions. Iron alloys are important structural materials used as components in fusion reactors, and a comprehensive database of their various properties has been developed. But little has been investigated on magnetic properties, in particular, the effects of high doses and helium cavities are lacking. Single-crystal iron films, with a thickness of 200 nm, were prepared using the ultra-high vacuum evaporation method. These films were then irradiated with 30 keV He+ ions at room temperature up to a dose of 18 dpa. X-ray diffraction measurements and cross-sectional transmission electron microscope observations revealed significant microstructural changes, including a large lattice expansion perpendicular to the film plane and the formation of high-density cavities after irradiation. However, the saturation magnetization and the shape of the magnetization curve showed almost no change, indicating the robustness of the magnetic properties of iron. [ABSTRACT FROM AUTHOR]

Developing large room temperature magnetoresistance materials has been a major hotspot for a few last decades due to its importance in the practical applications in magneto-resistive random access memory, and it remains a challenge. Here, La 0.9 Sr 0.1 Mn 1- y Zn y O 3 (LSMZO) films have been grown on SrTiO 3 substrates by magnetron sputtering, showing excellent quality of epitaxy. Upon increasing Zn content, the reduction of Curie temperature (T C) and metal-insulator transition temperature (T MI) is observed, accompanied by the increase of coercive field and room-temperature resistivity. Analysis on the fraction of Mn3+ and Mn4+ indicates that Zn2+ substitution at Mn site results in a higher Mn4+ fraction departing from the optimum value and hence a weaker double-exchange interaction by replacing more Mn3+. Besides that, ionic radius mismatch induced internal strain and substrate induced tensile strain also play a part. Most significantly, the enhanced magnetic disorder gives rise to an increase of intrinsic magnetoresistance around room temperature in LSMZO (y = 10%) film, and a large magnetoresistance of 18.4% is obtained under 0.3 T at 280 K in this sample. Our research provides a simple and effective approach to achieve a large room temperature magnetoresistance in Mn site doped manganite epitaxial films. [ABSTRACT FROM AUTHOR]

This study reports on the magnetic hardening phenomenon of heavily helium ion-irradiated iron–chromium alloys. The alloys are important structural materials in next-generation nuclear reactors. In some cases, problems may arise when the magnetic properties of the materials change due to neutron irradiation. Therefore, it is necessary to understand the effects of irradiation on magnetism. Helium irradiation was conducted as a simulated irradiation, and the effect of cavity formation on magnetic properties was thoroughly investigated. High-quality single-crystal Fe-x%Cr (x = 0, 10, 20) films, with a thickness of 180–200 nm, were fabricated through ultra-high vacuum evaporation. Subsequently, irradiation of 19 dpa with 30 keV He+ ions was conducted at room temperature. X-ray diffraction measurements and electron microscopy observations confirmed significant lattice expansion and the formation of high-density cavities after irradiation. The magnetization curve of pure iron remained unchanged, while magnetic hardening was noticed in iron–chromium alloys. This phenomenon is believed to be due to the combined effect of cavity formation and changes in the atomic arrangement of chromium.

ABSTRACTDuring cooling, conventional martensitic transformation can only be realized from austenite to martensite. Recently, a so-called reentrant martensitic transformation attracted much interest due to an additional transformation from martensite to austenite during further cooling. Obviously, materials with this reentrant transformation will increase the number of physical effects and possible applications. However, until now, only bulk samples have been available, which are not suitable for applications in micro-devices. In this work, we focus on the Co-Cr-Ga-Si system and examine the suitability of this system for the growth of thin films. We observed that the films grow epitaxially on MgO (100) substrates and exhibit a martensitic transformation if deposited at a sufficiently high temperature or with an additional heat treatment. Films within the austenite state are ferromagnetic while films within the martensitic state just exhibit a very low ferromagnetic order.

In this paper, calcium-doped p-type CuInO 2 (CuInO 2 :Ca) epitaxial films with c axis preferred orientation were grown on n-type GaN (001) substrates by the pulsed laser deposition (PLD) technology, and CuInO 2 /GaN p-n heterojunction photodetectors were fabricated based on the prepared CuInO 2 films. The lattice structure, surface morphology, energy band structure, composition, and electrical properties of the grown CuInO 2 :Ca films were characterized. Compared with the undoped and Ca-doped (1 at.%) films, the photoresponsivity (R), detectability (D*) and rise (τ r)/decay (τ d) time of the detector based on the CuInO 2 :Ca (2 at.%)) film with the best crystal quality are 1.13 mA/W, 9.9 × 1010 Jones, and 0.14/0.1 s, under the irradiation of 365 nm (21.5 mW/cm2) UV light with 0 V bias, respectively, and can achieve a maximum R-value of 1.6 mA/W under the lowest light intensity (2.4 mW/cm2). The results indicate that the self-powered UV photodetectors based on CuInO 2 /GaN p-n heterojunctions have potential applications in the field of optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this work, polycrystalline iron tin nitride films on different substrates with various nitrogen flow rates were deposited using the facing-target reactive sputtering method. Fe3SnN(111) epitaxial films were fabricated on both Al2O3(0001) and MgO(111) with two standard cubic centimeter per minute N2. The structures, electronic transport and magnetic properties were investigated systematically. The signs of the Hall resistivity slope in a high-field region are reversed when the temperature increases above 50 K, which suggests a temperature-induced transition of charge carriers from electron to hole. The longitudinal resistivity of films indicates metallic conductance mechanism. Different scaling laws were used to distinguish the physical mechanism underlying the observed anomalous Hall effect (AHE) in 60 nm thick Fe3SnN(111) epitaxial film. The skew scattering mechanism is demonstrated to play a dominant role in the AHE. This work not only offers a clear understanding of polycrystalline iron tin nitride films, but also contributes to the fabrication and applications of Fe3SnN(111) epitaxial films in spintronics. [ABSTRACT FROM AUTHOR]

In solidly mounted resonator (SMR) type of bulk acoustic wave resonator, it is difficult to fabricate single crystalline piezoelectric thin films in a bottom-up process due to the amorphous SiO _2 in the low acoustic impedance layer of the acoustic Bragg reflector. In this study, single crystalline ZnO piezoelectric layer on amorphous SiO _2 /polycrystalline Mo acoustic Bragg reflector is fabricated using a wet etching process of the epitaxial Au sacrificial layer. Epitaxial growth of ZnO was confirmed by X-ray diffraction pole figure and transmission electron microscope electron diffraction pattern. Resonance frequency of 1.3 GHz of epitaxial ZnO SMR was observed using a network analyzer.

This study reports on the microstructure and magnetism of pure iron irradiated with high doses of helium ions. Iron alloys are important structural materials used as components in fusion reactors, and a comprehensive database of their various properties has been developed. But little has been investigated on magnetic properties, in particular, the effects of high doses and helium cavities are lacking. Single-crystal iron films, with a thickness of 200 nm, were prepared using the ultra-high vacuum evaporation method. These films were then irradiated with 30 keV He+ ions at room temperature up to a dose of 18 dpa. X-ray diffraction measurements and cross-sectional transmission electron microscope observations revealed significant microstructural changes, including a large lattice expansion perpendicular to the film plane and the formation of high-density cavities after irradiation. However, the saturation magnetization and the shape of the magnetization curve showed almost no change, indicating the robustness of the magnetic properties of iron.

Epitaxial VO2 films grown by pulsed laser deposition (PLD) method with superior phase transition related switching characteristics are successfully embedded to SAW devices using concept of the "impedance loaded SAW sensor". A resistance of VO2 sensor abruptly drops from 0.7 M Ω to 90 Ω when it is heated above ∼ 65 ∘ C and shows a narrow hysteresis loops when switching. Two designs of SAW devices are examined in which RF signal is reflected back from interdigital transducer (IDT) or a surface acoustic waves (SAW) is transferred through a coupler and the RF response is altered 2 and 3 times correspondingly upon the phase transition in VO2. In the proposed devices with external load, a SAW does not propagate via VO2 film and therefore is not attenuated which is beneficiary for wireless applications. Additionally, a SAW phase shift as great as 50 ∘ is induced to the SAW transferred through the coupler due to the phase transition in VO2. The proposed approach may boost the development of remotely controlled autonomous sensors, including those based on VO2 metamaterials and hybrid plasmonic structures for near IR/middle IR and sub-THz/THz applications. [ABSTRACT FROM AUTHOR]

Epitaxial VO2 films grown by pulsed laser deposition (PLD) method with superior phase transition related switching characteristics are successfully embedded to SAW devices using concept of the “impedance loaded SAW sensor”. A resistance of VO2 sensor abruptly drops from 0.7 M[Formula: see text] to 90 [Formula: see text] when it is heated above [Formula: see text]65[Formula: see text]C and shows a narrow hysteresis loops when switching. Two designs of SAW devices are examined in which RF signal is reflected back from interdigital transducer (IDT) or a surface acoustic waves (SAW) is transferred through a coupler and the RF response is altered 2 and 3 times correspondingly upon the phase transition in VO2. In the proposed devices with external load, a SAW does not propagate via VO2 film and therefore is not attenuated which is beneficiary for wireless applications. Additionally, a SAW phase shift as great as 50[Formula: see text] is induced to the SAW transferred through the coupler due to the phase transition in VO2. The proposed approach may boost the development of remotely controlled autonomous sensors, including those based on VO2 metamaterials and hybrid plasmonic structures for near IR/middle IR and sub-THz/THz applications.

Epitaxial LaNiO3 (LNO) thin films prepared from the sols modified with polyethyleneimine (PEI) were grown on single-crystal LaAlO3, (LaAlO3)0.3(SrAlTaO6)0.7, and SrTiO3 substrates, respectively, using a simple polymer assisted deposition (PAD). The epitaxial structure, surface morphologies and transport of the LNO films were studied by X-ray diffraction (θ/2θ symmetric scan, ω-scan, and in-plane φ-scan), the field emission scanning electron microscopy, and a standard dc four-probe method. It is found that, compared with that of LNO bulk, the c-axis parameter of the LNO film increases under compressive strain and decreases under tensile strain. All the LNO films exhibit metal properties in the temperature-dependent resistivity. The resistivity of the LNO films shows an increasing trend with the lattice mismatch strain changing from compressive to tensile. It is suggested that the oxygen vacancy compensated by more Ni2+ changed from Ni3+ in the film increases with the strain changing from compressive to tensile, which results in the increase of the resistivity. [ABSTRACT FROM AUTHOR]

Epitaxial single-crystal MnSnO 3 thin films were deposited on single-crystal Al 2 O 3 substrates using pulsed laser deposition (PLD) technology, and an analysis was conducted on the impact of the growth temperature on the crystalline quality of the films. The test results show that the growth of MnSnO 3 thin films at 900 °C results in sharp diffraction peaks with high intensity in the c -axis direction, better crystalline quality (FWHM of XRD 2θ peak: 0.24°), less roughness (RSM: 0.67 nm) and wider optical band gap (E g = 2.91 eV) compared with the grown samples at other temperatures. The MnSnO 3 thin film deposited at 900 °C exhibits strong photoluminescence at 341.1 and 423.1 nm, as well as high ferroelectric polarization of ∼40 μC/cm2. The fabrication of epitaxial MnSnO 3 thin films opens up a new avenue for further research into their ferroelectric photovoltaic properties. [ABSTRACT FROM AUTHOR]

Epitaxial YBa 2 Cu 3 O 7‒δ (YBCO) films 150–200 and 300 nm thick, respectively, were deposited on SrTiO 3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R = 0) in the range of 77.4–87 R(T) depending on the conditions of deposition from one target with YBa 2 Cu 3 O 6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. %). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena. • Interfaces strongly affect the elemental distribution in YBaCuO films. • Y and Cu atoms on the surface predominate at crystallite sizes greater than 200 nm. • Impurity atoms on the surface in abundance at crystallite sizes of 2–200 nm. • Impurities stimulate the surface roughness of films. • Composition modulations along the C -axis affect the superconductivity in YBCO films. [ABSTRACT FROM AUTHOR]

To obtain epitaxial layers of A²B6 semiconductors with increased structural perfection from their own liquid phase, it has been proposed to use a technological process in which the synthesis temperature varies in such a manner that ensures a constant growth rate of layers during the whole process. The regularities of temperature variation with time for this process have been found on the basis of diffusion crystallization model. The developed model is realized by numerical methods and applied to description of the growth of cadmium telluride layers. Quantitative data on variations of synthesis temperature have been obtained, which can serve as a basis for choosing the temperature-time regimes of growth of cadmium telluride layers with a constant and required rate of solid phase formation. [ABSTRACT FROM AUTHOR]

We report on spin Hall magnetoresistance (SMR) in bilayers composed of Pt and magnetic insulator MgFe _2 O _4 (MFO) with spinel structure. The Pt thickness dependence of the SMR reveals that annealing of the MFO surface before depositing the Pt layer is crucial for a large SMR with better interface quality. We also found that oxygen pressure during the MFO growth hardly affects the SMR, while it influences the magnetic property of the MFO film. Our findings provide important clues to further understanding the spin transport at interfaces containing magnetic insulators, facilitating development of low power consumption devices.

Oxygen reduction and evolution reactions (ORR and OER, respectively) of perovskite-type La0.8Sr0.2CoO3 were characterized using two-dimensional model electrodes with different reaction planes (001), (110), and (111). Synthesized by pulsed laser deposition, these thin (30 nm) and flat (roughness < 1 nm) electrodes can reveal the reaction plane dependence of the ORR activity. From steady-state polarization measurements in KOH (aq.), the ORR activity was the highest on the (001) film during the first ORR/OER cycle, and it decreased significantly during the second cycle. In-situ synchrotron X-ray diffraction clarified crystal structure changes in the bulk and surface regions of La0.8Sr0.2CoO3, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the La0.8Sr0.2CoO3 surface partially decomposed upon reacting with the aqueous solution, as clarified by hard X-ray photoemission spectroscopy. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.

An easy and effective route to magnetic semiconducting ferrite oxynitrides with nitrogen doping tailored optical, magnetic, and electrical properties is developed by reactive magnetron sputtering. [Display omitted] • The nitrogen dopants in spinel ferrite (e.g., LiFe 5 O 8-x N y) epitaxial films have been systematically tailored by different deposition atmosphere. • Nitrogen doping can significantly enhance the light absorption and electrical performance for lithium ferrite films. • The nitrogen doping effect on the electronic structures and resultant properties of lithium ferrite has been elucidated by combined experimental and theoretical studies. The powerful means of nitrogen doping has been applied to perovskite, rocksalt, anatase, and fluorite oxides to tailor crystal structures, electronic/chemical states, and resultant physical/chemical properties for electronic/optical/magnetic device, catalysis, and energy conversion. However, it is rare for nitrogen-doped spinel oxides, especially for spinel ferrites. Here, we take spinel lithium ferrite (LiFe 5 O 8) as an archetype to elucidate the nitrogen doping effect on the optical, magnetic, and electrical properties. The nitrogen dopants in lithium ferrite oxynitride (LiFe 5 O 8-x N y) epitaxial films have been systematically manipulated by adjusting the deposition atmospheres during sputtering growth. Remarkably, nitrogen doping leads to a significant enhancement in both light absorption (approximately twice as enhanced at 2.1 eV) and electrical performance (up to 6 order enhancement) for lithium ferrites. The combined experimental and theoretical studies reveal that the nitrogen doping effect can effectively narrow the bandgap and create in-gap states that give rise to enhanced light absorption and electrical performance. Our study sheds light on a profound understanding of nitrogen doping-tailored crystal and electronic structures of spinel ferrites and provides a novel, easy, and effective route to magnetic semiconducting ferrite oxynitrides with boosted light absorption and electrical performance, which can be beneficial to spintronic and photochemistry applications. [ABSTRACT FROM AUTHOR]

The role of epitaxial strain and chemical termination in selected interfaces of perovskite oxide heterostructures is under intensive investigation because of emerging novel electronic properties. SrTiO$$_3$$ (STO) is one of the most used substrates for these compounds, and along its $$ \lt 001 \gt $$ direction allows for two nonpolar chemical terminations: TiO2 and SrO. In this paper, we investigate the surface morphology and crystal structure of SrO epitaxial ultrathin films: from 1 to about 25 layers grown onto TiO$$_2$$-terminated STO substrates. X-ray diffraction and transmission electron microscopy analysis reveal that SrO grows along its $$[111]$$ direction with a 4% out-of-plane elongation. This large strain may underlay the mechanism of the formation of self-organized pattern of stripes that we observed in the initial growth. We found that the distance between the TiO$$_2$$ plane and the first deposited SrO layer is $$0.27(3)$$ nm, a value which is about 40% bigger than in the STO bulk. We demonstrate that a single SrO-deposited layer has a different morphology compared to an ideal atomically flat chemical termination.

Structure change resulting from oxygen vacancies can strongly influence the chemical and physical properties of transition metal oxides, leading to new functionalities for novel electronic devices. In this work, by annealing LaBaCo 2 O 6-δ epitaxial films in different atmospheres, e.g., O 2 , N 2 and H 2 , we deduce that the concentration of oxygen vacancies and the stress in the film lattice imposed by the substrate play an important role in the ordering of oxygen vacancies in the LaBaCo 2 O 6-δ epitaxial films. Moreover, the structure changes resulting from the vacancy ordering have a direct influence on the electrical and optical properties of the epitaxial films. Experiment and simulation results demonstrate the chemical ordering of oxygen vacancies in LBCO epitaxial films. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Herein, the effect of γ -quanta on electrophysical and photoelectric properties of p-type Pb1-X MnX Se epitaxial films obtained from the molecular cluster on the glass substrate by the method of condensation has been investigated. It has been established that the acceptor-type local levels with the ionization energy of 0.14 eV and 0.175 eV are generated, when p-type Pb1-X MnX Se (x = 0.01) epitaxial films are irradiated by γ-quanta at D >10 kGy doses. The increase in the photoconductivity in the low temperature range 80-180K is due to the discharge of 0.14eV level, but the decrease in the rate of change of photocurrent in the high temperature range is due to the role of local level with 0.175 eV energy as a recombination center. [ABSTRACT FROM AUTHOR]

The role of epitaxial strain and chemical termination in selected interfaces of perovskite oxide heterostructures is under intensive investigation because of emerging novel electronic properties. SrTiO 3 (STO) is one of the most used substrates for these compounds, and along its < 001 > direction allows for two nonpolar chemical terminations: TiO2 and SrO. In this paper, we investigate the surface morphology and crystal structure of SrO epitaxial ultrathin films: from 1 to about 25 layers grown onto TiO 2 -terminated STO substrates. X-ray diffraction and transmission electron microscopy analysis reveal that SrO grows along its [ 111 ] direction with a 4% out-of-plane elongation. This large strain may underlay the mechanism of the formation of self-organized pattern of stripes that we observed in the initial growth. We found that the distance between the TiO 2 plane and the first deposited SrO layer is 0.27 (3) nm, a value which is about 40% bigger than in the STO bulk. We demonstrate that a single SrO-deposited layer has a different morphology compared to an ideal atomically flat chemical termination. [ABSTRACT FROM AUTHOR]

The role of epitaxial strain and chemical termination in selected interfaces of perovskite oxide heterostructures is under intensive investigation because of emerging novel electronic properties. SrTiO 3 (STO) is one of the most used substrates for these compounds, and along its < 001 > direction allows for two nonpolar chemical terminations: TiO2 and SrO. In this paper, we investigate the surface morphology and crystal structure of SrO epitaxial ultrathin films: from 1 to about 25 layers grown onto TiO 2 -terminated STO substrates. X-ray diffraction and transmission electron microscopy analysis reveal that SrO grows along its [ 111 ] direction with a 4% out-of-plane elongation. This large strain may underlay the mechanism of the formation of self-organized pattern of stripes that we observed in the initial growth. We found that the distance between the TiO 2 plane and the first deposited SrO layer is 0.27 (3) nm, a value which is about 40% bigger than in the STO bulk. We demonstrate that a single SrO-deposited layer has a different morphology compared to an ideal atomically flat chemical termination. [ABSTRACT FROM AUTHOR]

Ta-doped TiO2 (TiO2:Ta) films were synthesized on MgAl6O10 substrates by the metal-organic chemical vapor deposition (MOCVD) method. The doping uniformities, crystallization qualities, and optical properties of the deposited films were systematically characterized. The measurement results revealed the TiO2:Ta films with low Ta concentrations to be epitaxial anatase films with high transparency in the visible region. Thin-film transistors (TFTs) based on TiO2:Ta films were fabricated. The device with 0.5-at.% Ta-doped TiO2 as a channel layer exhibited clear n-type TFT behaviors with a high ${I} _{ \mathrm{\scriptscriptstyle ON}}/{I} _{ \mathrm{\scriptscriptstyle OFF}}$ ratio of $4.0\times 10^{{8}}$ , a low subthreshold swing of 0.60 V/decade, and a saturation mobility of 4.4 cm2V−1s−1. These parameters were superior to the values of previously reported TiO2-based devices and indicated that the Ta-doped TiO2 film was a promising channel material for transparent metal–oxide TFTs. [ABSTRACT FROM AUTHOR]

Studying size effects on the modification of thin film physical properties requires the preparation of films with desired microstructures and stress states. For the model system of epitaxial niobium thin films on sapphire [ 11 2 ¯ 0 , miscut < 0.1°] substrates surface topographies and stress states were systematically studied depending on the films' thickness (5 nm – 100 nm) and the deposition temperature (470 °C to 870 °C). Initial stresses, domain structures and textures of the films were characterized using X-ray diffraction techniques. The films' surface topographies were measured by scanning tunneling microscopy and atomic force microscopy, and classified into three different regimes: smooth (2D), rough (3D) and pitted (or 'meander-like'). Determination of the regimes' transition temperatures enables the tuning of the films microstructures and related stress states for each film thickness. • Topography of epitaxial Nb films depends on film thickness and deposition temperature. • Film surface splits up in 2D and 3D morphologies. • Tayloring of film topography and stress state is possible. • Proper sputter conditions for smooth films with thickness varying from 5 nm to 100 nm are deduced. [ABSTRACT FROM AUTHOR]

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Highlights • (1 1 1)-orientated face-center-cubic Zn x Co 1−x O (0 ≤ x ≤ 0.24) single crystal films were prepared. • Coexistence of antiferromagnetism and ferromagnetism was found in Zn x Co 1−x O films. • Antiferromagnetism of Zn x Co 1−x O layer was modulated by Zn composition and oxygen-plasma treatment. Abstract Recently antiferromagnetic materials become very attractive due to their new applications in spintronic devices. High-quality single crystal epitaxial Zn x Co 1−x O (1 1 1) thin films were grown by co-evaporating Zn and Co and simultaneously oxidizing in oxygen plasma. It is found that the exchange bias fields of Co/as-prepared Zn x Co 1−x O bilayers decrease with increasing Zn composition. When as-prepared Zn x Co 1−x O layer was annealed in oxygen plasma to remove oxygen vacancies, the exchange bias field of Co/oxygen-plasma-annealed Zn x Co 1−x O bilayers can be further enhanced. Moreover, a weak ferromagnetism was observed at 300 K in the as-prepared antiferromagnetic Zn x Co 1−x O film with oxygen vacancies, but it did not exist in oxygen-plasma-annealed Zn x Co 1−x O film. This indicates that oxygen vacancies can simultaneously weaken the antiferromagnetism but enhance the ferromagnetism of Zn x Co 1−x O layer. Therefore, we offer a method of manipulating the antiferromagnetism of Zn x Co 1−x O films by changing Zn composition and oxygen vacancies, which is useful for designing antiferromagnetic spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract Bismuth ruthenate (Bi 2 Ru 2 O 7) thin films were deposited on (111) yttria-stabilized zirconia (YSZ) single crystals and (111)YSZ//(111)Si substrates by chemical vapor deposition using Bi(CH 3) 2 [2-(CH 3) 2 NCH 2 C 6 H 4 ] and Ru(C 7 H 11)(C 7 H 9) as source materials and oxygen as a reactant gas. The film composition and X-ray diffraction ω -2 θ scan profiles for thin films deposited using various source flow rate ratios revealed the existence of a process window to obtain stoichiometric Bi 2 Ru 2 O 7. Within the process window, the kind of substrates did not strongly affect the deposition rates of Bi and Ru or the Bi/Ru ratio of the deposited films. It was also confirmed that the Bi 2 Ru 2 O 7 thin films grew epitaxially on both substrates within the process window. In particular, epitaxial Bi 2 Ru 2 O 7 thin films grew on the Si substrate with a YSZ buffer layer. Scanning electron microscopy revealed the formation of continuous dense Bi 2 Ru 2 O 7 films without any cracks or voids, and a relatively smooth interface between Bi 2 Ru 2 O 7 and the YSZ buffer layer on Si. The resistivity of the Bi 2 Ru 2 O 7 films was almost constant (~550 and ~950 μΩcm for the films deposited on (111)YSZ single-crystal substrates and (111)YSZ//(111)Si substrates, respectively), even when the ratio of Bi and Ru source gas flow rates was changed in the process window. In addition, the resistivity of Bi 2 Ru 2 O 7 films prepared on both kinds of substrates was almost independent of temperature from 10 to 300 K. Highlights • Bi 2 Ru 2 O 7 thin films were deposited by chemical vapor deposition process. • The process window for epitaxial pyrochlore Bi 2 Ru 2 O 7 film growth was confirmed. • The resistivity of the Bi 2 Ru 2 O 7 films was close to that of a single crystal Bi 2 Ru 2 O 7. [ABSTRACT FROM AUTHOR]