Precise local control of liquid crystal pretilt on polymer layers by focused ion beam nanopatterning

• Maxim V. Gorkunov,
• Irina V. Kasyanova,
• Vladimir V. Artemov,
• Alena V. Mamonova and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2019, 10, 1691–1697, doi:10.3762/bjnano.10.164

• Institute), 115409 Moscow, Russia 10.3762/bjnano.10.164 Abstract Background: The alignment of liquid crystals by surfaces is crucial for applications. It determines the director configuration in the bulk, its stability against defects and electro-optical switching scenarios. The conventional planar

• their reliable electro-optical switching [1]. The reason is of fundamental nature: Anisotropic LC phases arise due to collective intermolecular interactions in the LC bulk that allow for different LC orientations in the laboratory frame. Without external alignment, LC samples are randomly multi-domain

• example, helps avoiding topological defects [11] and accelerates switching of vertically aligned LC cells [12]. It is quantitatively characterized by the pretilt angle between the director and the surface plane. Surfaces stabilizing pretilted alignments remain rare and require more complex fabrication

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• [1], hydrogen production [2], resistive switching [3] and organic electronics [4][5] to so-called thermoelectric power generators [6]. The performance of all of the abovementioned applications is extremely sensitive to the work function (WF) of the active oxide layer. As a vast majority of

Materials nanoarchitectonics at two-dimensional liquid interfaces

• Katsuhiko Ariga,
• Michio Matsumoto,
• Taizo Mori and
• Lok Kumar Shrestha

Beilstein J. Nanotechnol. 2019, 10, 1559–1587, doi:10.3762/bjnano.10.153

• molecular controls based on external stimuli switching [184][185][186][187][188] (basics for molecular machines, Nobel prize in 2016 [189][190][191]). The anisotropic dynamics at liquid interfaces described above are expected to play a crucial role in the production of low-dimensional materials and systems

Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson “atoms”

• Daria V. Popolitova,
• Nikolay V. Klenov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2019, 10, 1548–1558, doi:10.3762/bjnano.10.152

• time of population transfer (or “Not”-operation, TNOT) is normalized by TΩ = 2π/Ω. While this period is in the sub-nanosecond range, the time of the considered gate appears to be up to two orders of magnitude lower. Thus we really achieve very fast gates with switching times of the order of picoseconds

• parasitic plasma oscillations of the circuit and field in the optimal mode of operation after carrying out the required impact on the Josephson meta-atom. Conclusion In this paper we develop a theoretical concept and its experimental realization of ultrafast switching between selected eigenstates of an

• experimental scheme with the possibility to block the required transitions and to adjust the energy spectrum and matrix elements to their optimal values obtained from our theoretical consideration. Switching the regimes from the simple Λ-scheme to the specific case of a Δ-atom is shown and the possibility to

Superconducting switching due to a triplet component in the Pb/Cu/Ni/Cu/Co₂Cr_1−xFe_xAl_y spin-valve structure

• Andrey Andreevich Kamashev,
• Nadir Nurgayazovich Garif’yanov,
• Aidar Azatovich Validov,
• Joachim Schumann,
• Vladislav Kataev,
• Bernd Büchner,
• Yakov Victorovich Fominov and
• Ilgiz Abdulsamatovich Garifullin

Beilstein J. Nanotechnol. 2019, 10, 1458–1463, doi:10.3762/bjnano.10.144

• suggests that the observed minimum and the corresponding full switching effect of the spin valve is caused by the long-range triplet component of the superconducting condensate in the multilayer. Such a large effect can be attributed to a half-metallic nature of the HA layer, which in the orthogonal

• , 5, 021019, in achieving large values of the switching effect. Keywords: ferromagnet; proximity effect; superconductor; Introduction For decades, metallic thin-film heterostructures have been in the in the focus of fundamental research in condensed matter physics and materials science. They show

• a magnitude of the SSV effect (where and are the SC transition temperatures for the AP and P orientation of the magnetization of the F1 and the F2 layer) of 6 mK and a width of the SC transition curves δTc≈ 0.1 K. Unfortunately, the full switching between the normal and SC states could not be

On the relaxation time of interacting superparamagnetic nanoparticles and implications for magnetic fluid hyperthermia

• Andrei Kuncser,
• Nicusor Iacob and
• Victor E. Kuncser

Beilstein J. Nanotechnol. 2019, 10, 1280–1289, doi:10.3762/bjnano.10.127

• suggest that anisotropy energy barriers and hence the switching time provided by Equation 5 may be altered by the volume fraction of the system of monodisperse (identical) nanoparticles. However, any information on the characteristic time constant τ0 is out of reach with this approach and this aspect will

• be investigated further by time-dependent simulations. Time-dependent approach: simulation and data analysis The magnetic switching of each nanoparticle in all three geometric configurations described above has been investigated via time-dependent (dynamic) micromagnetic simulations (numerical

• provides both the anisotropy energy barrier ΔE* and the relaxation time constant τ0* assumed to be affected by the interparticle interactions. It is worth noting that the above-mentioned methodology depends critically on the reliability in the determination of the relaxation time (or switching frequency

Fe₃O₄ nanoparticles as a saturable absorber for giant chirped pulse generation

• Ji-Shu Liu,
• Xiao-Hui Li,
• Abdul Qyyum,
• Yi-Xuan Guo,
• Tong Chai,
• Hua Xu and
• Jie Jiang

Beilstein J. Nanotechnol. 2019, 10, 1065–1072, doi:10.3762/bjnano.10.107

• pulse duration of 55 ns, which is the shortest pulse duration published to date. It is well-established that the RPR will increase with the increase in pump power when the device is in the Q-switching state [40][41][43][44][45][46]. In our results, we demonstrate that as the pump power is increased, the

Rapid, ultraviolet-induced, reversibly switchable wettability of superhydrophobic/superhydrophilic surfaces

• Yunlu Pan,
• Wenting Kong,
• Bharat Bhushan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2019, 10, 866–873, doi:10.3762/bjnano.10.87

• and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue, Columbus, OH 43210-1142, USA 10.3762/bjnano.10.87 Abstract Controllable wettability is important for a wide range of applications, including intelligent switching, self-cleaning and oil/water separation. In this work, rapid

• switching and extreme wettability changes upon ultraviolet (UV) illumination were investigated. TiO2 nanoparticles were modified in solutions of trimethoxy(alkyl)silane, and the suspensions were sprayed on glass substrates. For such samples, the water contact angle (WCA) was shown to transition from a

• surfaces in a suspension of TiO2 modified with trimethoxypropyl saline. In this work, the wettability transition time from superhydrophobic (WCA ≈ 158°) to superhydrophilic (WCA ≈ 0°) occurred within 120 min of UV illumination. Although large range wettability switching can be achieved in many ways, the

Co-doped MnFe₂O₄ nanoparticles: magnetic anisotropy and interparticle interactions

• Bagher Aslibeiki,
• Parviz Kameli,
• Hadi Salamati,
• Giorgio Concas,
• Maria Salvador Fernandez,
• Alessandro Talone,
• Giuseppe Muscas and
• Davide Peddis

Beilstein J. Nanotechnol. 2019, 10, 856–865, doi:10.3762/bjnano.10.86

• provided additional information about the magnetization reversal of each sample. The derivative of MDCD with respect to the reversal field, χirr = dMDCD/dµ0H, represents the irreversible component of the susceptibility. This quantity is generally defined as the switching field distribution (SFD) [47][48

• . Only sample C0 is fully superparamagnetic at room temperature, while the only blocked sample is C100. (a) Magnetization vs field curves and (b) switching field distribution measured at 5 K for sample C0 (black squares), C25 (red circles), C50 (blue triangles), C75 (dark cyan reversed triangles), and

Novel reversibly switchable wettability of superhydrophobic–superhydrophilic surfaces induced by charge injection and heating

• Xiangdong Ye,
• Junwen Hou and
• Dongbao Cai

Beilstein J. Nanotechnol. 2019, 10, 840–847, doi:10.3762/bjnano.10.84

• Xiangdong Ye Junwen Hou Dongbao Cai School of Mechanical and Electrical Engineering, Shaanxi Key Laboratory of Nano Materials and Technology, Xi’an University of Architecture and Technology, Xi’an 710055, China 10.3762/bjnano.10.84 Abstract Reversibly switching wettability between

• for converting superhydrophobic surfaces into superhydrophilic surfaces after only 10 min of ultraviolet irradiation. Gao et al. [6] prepared 18 alkyltrichlorosilane-modified TiO2 films for the reversible switching between superhydrophilicity and superhydrophobicity of a wood surface. Feng et al. [7

• contact angle of 0°. Li et al. [8] prepared a superhydrophobic and superhydrophilic zinc oxide film on a bamboo surface. The surface was irradiated by ultraviolet radiation/darkroom for 12 h. A storage period of ten days induced the reversible switching between superhydrophilicity and superhydrophobicity

Periodic Co/Nb pseudo spin valve for cryogenic memory

• Nikolay Klenov,
• Yury Khaydukov,
• Sergey Bakurskiy,
• Roman Morari,
• Igor Soloviev,
• Vladimir Boian,
• Thomas Keller,
• Mikhail Kupriyanov,
• Anatoli Sidorenko and
• Bernhard Keimer

Beilstein J. Nanotechnol. 2019, 10, 833–839, doi:10.3762/bjnano.10.83

• memory applications. As a basis for a weak link we propose to use a periodic structure composed of ferromagnetic (F) layers spaced by thin superconductors (s). Our calculations based on the Usadel equations show that switching from parallel (P) to antiparallel (AP) alignment of neighboring F layers can

• the feasibility of controllable switching between AP and P states through the whole periodic structure, we prepared a superlattice [Co(1.5 nm)/Nb(8 nm)/Co(2.5 nm)/Nb(8 nm)]6 between two superconducting layers of Nb(25 nm). Neutron scattering and magnetometry data showed that parallel and antiparallel

• ], and also due to compatibility with a number of quantum and neuromorphic computers under development [2][3][4]. However the lack of cryogenic memory elements (including synapses) with sufficiently fast switching between stable states and sufficiently small energy dissipation is still the main obstacle

Coexisting spin and Rabi oscillations at intermediate time regimes in electron transport through a photon cavity

• Vidar Gudmundsson,
• Hallmann Gestsson,
• Nzar Rauf Abdullah,
• Chi-Shung Tang,
• Andrei Manolescu and
• Valeriu Moldoveanu

Beilstein J. Nanotechnol. 2019, 10, 606–616, doi:10.3762/bjnano.10.61

• transport in the far-infrared (FIR) regime. The time-dependent electronic transport through a two-dimensional (2D) nanosystem patterned in a GaAs heterostructure, which is in turn embedded in a three-dimensional (3D) FIR photon cavity, generally displays three regimes: i) The switching transient regime in

Temperature-dependent Raman spectroscopy and sensor applications of PtSe₂ nanosheets synthesized by wet chemistry

• Mahendra S. Pawar and
• Dattatray J. Late

Beilstein J. Nanotechnol. 2019, 10, 467–474, doi:10.3762/bjnano.10.46

• function of temperature. PtSe2 nanosheet based humidity sensor: (a) Typical resistance versus relative humidity plot and (b) current–time (I–t) plot taken after switching 11% RH and 97% RH. The photodetector application of PtSe2 nanosheets: (c) I–V in dark conditions and with green LED light and (d

Integration of LaMnO_3+δ films on platinized silicon substrates for resistive switching applications by PI-MOCVD

• Raquel Rodriguez-Lamas,
• Dolors Pla,
• Odette Chaix-Pluchery,
• Benjamin Meunier,
• Fabrice Wilhelm,
• Andrei Rogalev,
• Laetitia Rapenne,
• Xavier Mescot,
• Quentin Rafhay,
• Hervé Roussel,
• Michel Boudard,
• Carmen Jiménez and
• Mónica Burriel

Beilstein J. Nanotechnol. 2019, 10, 389–398, doi:10.3762/bjnano.10.38

• and reduction of the power consumption. In this context, resistive switching memory chips emerge as promising candidates for developing new non-volatile memory modules. Manganites have received increasing interest as memristive material as they exhibit a remarkable switching response. Nevertheless

• technique. We have developed three different growth strategies with which we are able to tune the oxygen content and Mn oxidation state moving from an orthorhombic to a rhombohedral structure for the active LaMnO3+δ material. Furthermore, a good resistive switching response has been obtained for LaMnO3+δ

• -based devices fabricated using optimized growth strategies. Keywords: manganite; metal organic chemical vapour deposition (MOCVD); resistive switching; thin film; valence-change memory; Introduction Resistive switching (RS) denotes the phenomena occurring in capacitor-like heterostructures (metal

Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes

• Mateusz Mrukiewicz,
• Krystian Kowiorski,
• Paweł Perkowski,
• Rafał Mazur and
• Małgorzata Djas

Beilstein J. Nanotechnol. 2019, 10, 71–78, doi:10.3762/bjnano.10.7

• , electric anisotropy, splay elastic constant, switch-on time, and switch-off time. The shape and dimensions of the GO flakes were studied using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The influence of the GO concentration on the physical properties and switching process in the

• presence of the electric field was discussed. Keywords: graphene oxide; liquid crystal; nematic phase; switching; threshold voltage; Introduction Liquid crystals (LCs) are classified as a type of soft matter which are characterized by anisotropic molecules and a liquid-like fluidity behavior. Of all LC

• composites [11][12][13][14]. NLCs doped with graphene or carbon nanotubes show a faster response in electro-optical switching than pure liquid crystal compounds. This effect is caused by trapping of some free ion concentrations [15][16] or reduction in the rotational viscosity [17]. Furthermore, due to

Electrostatic force microscopy for the accurate characterization of interphases in nanocomposites

• Diana El Khoury,
• Richard Arinero,
• Jean-Charles Laurentie,
• Mikhaël Bechelany,
• Michel Ramonda and
• Jérôme Castellon

Beilstein J. Nanotechnol. 2018, 9, 2999–3012, doi:10.3762/bjnano.9.279

• lock-in amplifier (EG&G Instruments – Model 5302), locked at the double frequency of the AC-electrical excitation and an arbitrary function generator (Sony Tektronic – AFG310). A custom-made switching device was used to extract the 2ω component from the signal obtained during the second pass. A 5 V AC

Charged particle single nanometre manufacturing

• Philip D. Prewett,
• Cornelis W. Hagen,
• Claudia Lenk,
• Steve Lenk,
• Marcus Kaestner,
• Tzvetan Ivanov,
• Ahmad Ahmad,
• Ivo W. Rangelow,
• Xiaoqing Shi,
• Stuart A. Boden,
• Alex P. G. Robinson,
• Dongxu Yang,
• Sangeetha Hari,
• Marijke Scotuzzi and
• Ejaz Huq

Beilstein J. Nanotechnol. 2018, 9, 2855–2882, doi:10.3762/bjnano.9.266

Contactless photomagnetoelectric investigations of 2D semiconductors

• Marian Nowak,
• Marcin Jesionek,
• Barbara Solecka,
• Piotr Szperlich,
• Piotr Duka and
• Anna Starczewska

Beilstein J. Nanotechnol. 2018, 9, 2741–2749, doi:10.3762/bjnano.9.256

• . Results and Discussion Figure 5a shows the induced VPME response to the switching on and switching off of the sinusoidally modulated illumination of single-layer graphene with and without a magnetic field. The measured VPME responses are proportional to the magnetic field induction (Figure 5b) and to the

• electrostatically tunable carrier density. The charge carriers can change from electrons to holes with the application of an electrostatic gate. The switching takes place at the Dirac point, where the carriers have a minimum density. The gate voltage, Vg, induces a sheet carrier concentration approximated by [33

• the energy position of Fermi level and the switching between 2D electron and hole gases by changing the gate voltage. Taking into account the proportionality of the PME magnetic flux to the square of carrier mobility and lifetime presented above (Figure 2) (i.e., in the case of small values of μτ and

Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

• Pavel Loiko,
• Tanujjal Bora,
• Josep Maria Serres,
• Haohai Yu,
• Magdalena Aguiló,
• Francesc Díaz,
• Uwe Griebner,
• Valentin Petrov,
• Xavier Mateos and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2018, 9, 2730–2740, doi:10.3762/bjnano.9.255

• nanorods; Q-switching; saturable absorption; solid-state lasers; zinc oxide; Introduction Zinc oxide (ZnO) is a well-known II–IV group wide-bandgap semiconductor (Eg = 3.37 eV), possessing a hexagonal wurtzite-type (sp. gr. P63mc) structure with unit cell parameters a = 3.25 Å, c = 5.20 Å. In recent years

• with picosecond pulses resulting in Isat = 16 kW/cm2, which is close to our observations. Passive Q-switching by ZnO nanorods The laser experiments were performed with the NRs grown for 5 h, because they exhibited minimum insertion loss. Stable Q-switching was also observed for the NRs grown for 10 h

• scaling of the laser in the PQS regime was limited by the Q-switching instabilities arising for Pabs > 3.2 W due to the heating of the SA by the residual (non-absorbed) pump [22]. The pulse duration Δτ, determined as full width at half maximum (FWHM) and the pulse repetition frequency (PRF) for the PQS

Size-selected Fe₃O₄–Au hybrid nanoparticles for improved magnetism-based theranostics

• Maria V. Efremova,
• Yulia A. Nalench,
• Eirini Myrovali,
• Anastasiia S. Garanina,
• Ivan S. Grebennikov,
• Polina K. Gifer,
• Maxim A. Abakumov,
• Marina Spasova,
• Makis Angelakeris,
• Alexander G. Savchenko,
• Michael Farle,
• Natalia L. Klyachko,
• Alexander G. Majouga and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2018, 9, 2684–2699, doi:10.3762/bjnano.9.251

• magnetic heating contribution by using where C is the volumetric specific heat capacity of the sample, mf the dispersion mass, mMNPs is the iron mass diluted in the dispersion and ΔΤ/Δt is the maximal slope at initial time after switching on the heating AC field. In vitro experiments Cell culture. 4T1

Nanoantenna structures for the detection of phonons in nanocrystals

• Alexander G. Milekhin,
• Sergei A. Kuznetsov,
• Ilya A. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Alexander V. Latyshev,
• Volodymyr M. Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2018, 9, 2646–2656, doi:10.3762/bjnano.9.246

• obtained for three different angles of incidence θ = 0, 25, and 50°. Since the longitudinal LSPR mode can be excited either by TE- (E0 II X) or TM-polarized (H0 II Y) waves, both geometries are considered in the simulations. Note that switching to the second derivative of d instead of the dipole moment

Effective sensor properties and sensitivity considerations of a dynamic co-resonantly coupled cantilever sensor

• Julia Körner

Beilstein J. Nanotechnol. 2018, 9, 2546–2560, doi:10.3762/bjnano.9.237

• magnetic properties. This led to the first time observation of magnetic switching of these individual Heusler nanoparticles at room temperature and with a comparatively simple setup (laser-deflection detection) [16]. Other experiments in magnetic force microscopy showed a likewise increase in sensitivity

Evidence of friction reduction in laterally graded materials

• Roberto Guarino,
• Gianluca Costagliola,
• Federico Bosia and
• Nicola Maria Pugno

Beilstein J. Nanotechnol. 2018, 9, 2443–2456, doi:10.3762/bjnano.9.229

• coefficient of friction when switching from the 0° to the 90° direction, and this is evident especially for large values of Δ. The dependence of µs on the angle, instead, is more complex for Δ < 0.3, especially for the 3D FEM, where the interaction with the vertical stress distribution must also be taken into

Pinning of a ferroelectric Bloch wall at a paraelectric layer

• Vilgelmina Stepkova and
• Jiří Hlinka

Beilstein J. Nanotechnol. 2018, 9, 2356–2360, doi:10.3762/bjnano.9.220

• loop demonstrating switching of the Pt component of the Bloch wall located at a 1 nm thin SrTiO3 layer. The indicated value of the polarization Pt is averaged over the whole supercell shown in Figure 1b. Acknowledgements This work was supported by the Czech Science Foundation (project no. 15-04121S

Magnetism and magnetoresistance of single Ni–Cu alloy nanowires

• Andreea Costas,
• Camelia Florica,
• Elena Matei,
• Maria Eugenia Toimil-Molares,
• Ionel Stavarache,
• Andrei Kuncser,
• Victor Kuncser and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2018, 9, 2345–2355, doi:10.3762/bjnano.9.219

• , the magnetization reversal canb be described using the Stoner–Wohlfarth model [29][30]. Thus, if the field is applied along the easy axis (EA), the magnetization changes steeply its orientation along the EA at a switching field proportional to the anisotropy constant and inversely proportional to the

• decrease of the magnetization from positive to negative saturation, with the saturation field equating the switching field in parallel geometry. If the current flows along the EA, the resistivity is above the saturation field (θ = 90°) and at zero field (where the magnetization lies along the EA, due to

• perpendicular to the easy axis. The saturation field (approaching the switching field in case of the S–W model) decreases very slowly with the Ni composition, contrary to what would be expected from the composition dependence of the saturation magnetization and inverse proportionality of the switching field