Molecular assemblies on surfaces: towards physical and electronic decoupling of organic molecules

• Sabine Maier and
• Meike Stöhr

Beilstein J. Nanotechnol. 2021, 12, 950–956, doi:10.3762/bjnano.12.71

• assemblies [23][28][60][61]. Similarly, the lack of electronic states around the Fermi level in a superconductor was used to preserve electronic properties in adsorbed molecules. For example, the spin relaxation in magnetic molecules was suppressed on a superconducting surface, which then resulted in a

In situ transport characterization of magnetic states in Nb/Co superconductor/ferromagnet heterostructures

• Olena M. Kapran,
• Roman Morari,
• Taras Golod,
• Evgenii A. Borodianskyi,
• Vladimir Boian,
• Andrei Prepelita,
• Nikolay Klenov,
• Anatoli S. Sidorenko and
• Vladimir M. Krasnov

Beilstein J. Nanotechnol. 2021, 12, 913–923, doi:10.3762/bjnano.12.68

• Functional Nanostructures, Orel State University named after I.S. Turgenev, 302026, Russia 10.3762/bjnano.12.68 Abstract Employment of the non-trivial proximity effect in superconductor/ferromagnet (S/F) heterostructures for the creation of novel superconducting devices requires accurate control of magnetic

• ][34][35] in various superconductor/ferromagnet (S/F) heterostructures. It is anticipated, that this phenomenon can be employed for the creation of novel superconducting devices, in which the supercurrent is determined and controlled by the magnetic state of the heterostructure, that is, by the

A review of defect engineering, ion implantation, and nanofabrication using the helium ion microscope

• Frances I. Allen

Beilstein J. Nanotechnol. 2021, 12, 633–664, doi:10.3762/bjnano.12.52

• was first demonstrated by Cybart et al. for the cuprate superconductor YBa2Cu3O7−δ (YBCO), by scanning the helium ion beam in line mode across 4 μm wide strips of YBCO that had been locally pre-thinned to a thickness of 30 nm using argon ion milling [31]. Due to the high-resolution writing capability

• remain narrow and confined. In contrast, in a study based on another cuprate-based superconductor, La1.84Sr0.16CuO4 (LSCO), it was found that significantly higher doses (1018 ions/cm2) were necessary to induce resistive behavior [47], that is, an order of magnitude higher than the respective dose for

• YBCO. Moreover, significant lateral scatter of the helium ions in the LSCO thin film was observed, even for the lower doses, exacerbated by ion backscatter from the substrate interface. However, in the case of another high-temperature superconductor, MgB2, the creation of high-quality Josephson

Molecular dynamics modeling of the influence forming process parameters on the structure and morphology of a superconducting spin valve

• Alexander Vakhrushev,
• Aleksey Fedotov,
• Vladimir Boian,
• Roman Morari and
• Anatolie Sidorenko

Beilstein J. Nanotechnol. 2020, 11, 1776–1788, doi:10.3762/bjnano.11.160

• superconductor nanolayers. The aim was to study the influence of the main technological parameters including temperature, concentration and spatial distribution of deposited atoms over the nanosystem surface on the atomic structure and morphology of the nanosystem. The studies were carried out using the

• atomic structures depending on the main parameters of the deposition process. Keywords: hybrid nanostructure; mathematical modeling; modified embedded-atom method; molecular dynamics; spintronics; spin valve; vacuum deposition; Introduction Multilayer superconductor/ferromagnetic (S/F) hybrid

• quantum-mechanical transparency of the interface, TF, was assigned. Here, they considered the effect of the mutual solubility of the metals (of a superconductor and a ferromagnet) on the quantum-mechanical transparency. The transparency parameter of the interface for completely non-wetting metals, such as

Functional nanostructures for electronics, spintronics and sensors

• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2020, 11, 1704–1706, doi:10.3762/bjnano.11.152

• superconductor digital technology (SDT) [4]. The switching energy of the SDT basic element is on the order of 10−19 J (including the power for cryogenic cooling of superconducting circuits), which demonstrates an energy efficiency of up to seven orders of magnitude as compared to the semiconductor analog [5

• bit-op/J at a temperature of 4 K. A prospective investigation found that a superconductor computer could outperform its semiconductor competitor by two orders of magnitude in energy efficiency, demonstrating 250 GFLOPS/W [7]. The base elements of the superconductor computer are superconductor logic

• functional nanostructures consisting of alternating layers of ferromagnetic and superconducting materials – has been observed. Due to the proximity effect of superconductor/ferromagnetic (S/F) layers and Andreev reflection of Cooper pairs at the S/F interface, a number of new phenomena were first

Superconductor–insulator transition in capacitively coupled superconducting nanowires

• Alex Latyshev,
• Andrew G. Semenov and
• Andrei D. Zaikin

Beilstein J. Nanotechnol. 2020, 11, 1402–1408, doi:10.3762/bjnano.11.124

• Moscow, Russia Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany 10.3762/bjnano.11.124 Abstract We investigate superconductor–insulator quantum phase transitions in ultrathin capacitively coupled superconducting nanowires with

• superconductor–insulator phase transition in each of the wires is controlled not only by its own parameters but also by those of the neighboring wire as well as by mutual capacitance. We argue that superconducting nanowires with properly chosen parameters may turn insulating once they are brought sufficiently

• ]. Below we will also refer to this QPT as a superconductor–insulator transition (SIT). In this work we will show that this SIT can be substantially modified in a system of capacitively coupled superconducting nanowires even without any direct electrical contact between them. In our previous work [18] we

Controlling the proximity effect in a Co/Nb multilayer: the properties of electronic transport

• Sergey Bakurskiy,
• Mikhail Kupriyanov,
• Nikolay V. Klenov,
• Igor Soloviev,
• Andrey Schegolev,
• Roman Morari,
• Yury Khaydukov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2020, 11, 1336–1345, doi:10.3762/bjnano.11.118

• We present both theoretical and experimental investigations of the proximity effect in a stack-like superconductor/ferromagnetic (S/F) superlattice, where ferromagnetic layers with different thicknesses and coercive fields are made of Co. Calculations based on the Usadel equations allow us to find

• superlattices can be used as tunable kinetic inductors designed for artificial neural networks representing the information in a “current domain”. Keywords: cryogenic computing; spin-valve; superconducting neural network; superconducting spintronics; Introduction Multilayer superconductor/ferromagnetic (S/F

• which the thick S-bank acts as the source of induced superconductivity, is the simplest model of the 3D structure. Let us consider the applications that are possible due to the control over the order parameter in thin superconductor layers (s-layers) in such a structure. The simplest cell for the

Cryogenic low-noise amplifiers for measurements with superconducting detectors

• Ilya L. Novikov,
• Boris I. Ivanov,
• Dmitri V. Ponomarev and
• Aleksey G. Vostretsov

Beilstein J. Nanotechnol. 2020, 11, 1316–1320, doi:10.3762/bjnano.11.115

• -precision calibration of superconductor technology and for finding new noise sources in Josephson junctions, which lead to high decoherence in superconducting systems [2][3]. The most important part in a measurement readout is a low-noise amplifier. The modern low-temperature low-noise cryogenic amplifiers

Proximity effect in [Nb(1.5 nm)/Fe(x)]₁₀/Nb(50 nm) superconductor/ferromagnet heterostructures

• Yury Khaydukov,
• Sabine Pütter,
• Laura Guasco,
• Roman Morari,
• Gideok Kim,
• Thomas Keller,
• Anatolie Sidorenko and
• Bernhard Keimer

Beilstein J. Nanotechnol. 2020, 11, 1254–1263, doi:10.3762/bjnano.11.109

• ferromagnetic properties. The proximity of this weak ferromagnetic layer to a thick superconductor leads to an intermediate phase that is characterized by a suppressed but still finite resistance of structure in a temperature interval of about 1 K below the superconducting transition of thick Nb. By increasing

• ; superconductor; Introduction Superconductor(S)/ferromagnet(F) heterostructures are intensively studied systems, which are interesting for fundamental physics due to a big number of predicted and detected phenomena such as the appearance of non-uniform superconducting states (see reviews [1][2][3]). Among these

• not observe any antiferromagnetic coupling, neither at room temperature nor in low-temperature measurements. The reason of this disagreement may originate from the amorphous Nb spacers. The proximity of this depth-modulated and weakly magnetic layer to a thick superconductor causes the appearance of

Nonadiabatic superconductivity in a Li-intercalated hexagonal boron nitride bilayer

• Kamila A. Szewczyk,
• Izabela A. Domagalska,
• Artur P. Durajski and
• Radosław Szczęśniak

Beilstein J. Nanotechnol. 2020, 11, 1178–1189, doi:10.3762/bjnano.11.102

• superconductor–metal phase transition is about 25 K [41] for the Coulomb pseudopotential μ* = 0.14 (identical to the experimental value of μ* obtained for graphene [46]). The expected value of TC is much higher than the maximum temperature that was achieved in graphene intercalated with alkali metals (TC = 8.1 K

• Li-hBN is related to the fact that the physical system is quasi-two-dimensional. In the case of the bulk superconductor, the width of the electron band is significantly broadened, which results in the increase of the Fermi energy (εF = 1.63 eV). In addition, the electron–phonon coupling constant

A Josephson junction based on a highly disordered superconductor/low-resistivity normal metal bilayer

• Pavel M. Marychev and
• Denis Yu. Vodolazov

Beilstein J. Nanotechnol. 2020, 11, 858–865, doi:10.3762/bjnano.11.71

• composed of a highly disordered superconductor (S) and a low-resistivity normal metal (N) with proximity-induced superconductivity. In such a junction, the N layer provides both a large concentration of phase in the weak link and good heat dissipation. We find that when the thickness of the S and the N

• layer and the length of the S constriction are about the superconducting coherence length the CPR is single-valued and can be close to a sinusoidal shape. The product IcRn can reach Δ(0)/2|e| (Ic is the critical current of the junction, Rn is its normal-state resistance, Δ(0) is the superconductor gap

• of a single S layer at zero temperature). Our calculations show, that the proper choice of the thickness of the N layer leads both to nonhysteretic current–voltage characteristics even at low temperatures and a relatively large product IcRn. Keywords: normal metal–superconductor bilayer; Josephson

Epitaxial growth and superconducting properties of thin-film PdFe/VN and VN/PdFe bilayers on MgO(001) substrates

• Wael M. Mohammed,
• Igor V. Yanilkin,
• Amir I. Gumarov,
• Airat G. Kiiamov,
• Roman V. Yusupov and
• Lenar R. Tagirov

Beilstein J. Nanotechnol. 2020, 11, 807–813, doi:10.3762/bjnano.11.65

• ; epitaxial superconductor–ferromagnet heterostructure; palladium–iron alloy (PdFe); vanadium nitride (VN); superconducting spintronics; Introduction Since its invention, rapid single-flux quantum (RSFQ) logic [1][2] based on superconducting digital electronics has been seriously considered as an alternative

• of niobium as a superconductor with a Pd1−xFex alloy as a soft and weak ferromagnet was considered as material of choice for superconducting magnetic random access memories (MRAM) [8][29][30]. However, no further developments towards a prototype using a Pd1−xFex alloy have been demonstrated. There

• choice for superconducting MRAM materials, in which vanadium nitride (VN) serves as the superconductor. The magnetic anisotropies of a 20 nm thick Pd0.96Fe0.04 film of the first-generation epitaxial sample of VN/Pd0.96Fe0.04 on MgO(001) were studied by using a ferromagnetic resonance technique in [34

High dynamic resistance elements based on a Josephson junction array

• Konstantin Yu. Arutyunov and
• Janne S. Lehtinen

Beilstein J. Nanotechnol. 2020, 11, 417–420, doi:10.3762/bjnano.11.32

• of Jyvaskyla, PB 35, FI-40014 Jyvaskyla, Finland 10.3762/bjnano.11.32 Abstract A chain of superconductor–insulator–superconductor junctions based on Al–AlOx–Al nanostructures and fabricated using conventional lift-off lithography techniques was measured at ultra-low temperatures. At zero magnetic

• situ to form tunnel barriers. Each sample consisted of 25 pairs of JJs connected in parallel where the area of each superconductor–insulator–superconductor (SIS) contact was about 100 × 100 nm (Figure 1). The samples were analyzed by scanning electron microscopy (SEM) (Figure 1) and atomic force

Anomalous current–voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers

• Tairzhan Karabassov,
• Anastasia V. Guravova,
• Aleksei Yu. Kuzin,
• Elena A. Kazakova,
• Shiro Kawabata,
• Boris G. Lvov and
• Andrey S. Vasenko

Beilstein J. Nanotechnol. 2020, 11, 252–262, doi:10.3762/bjnano.11.19

• Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia 10.3762/bjnano.11.19 Abstract We present a quantitative study of the current–voltage characteristics (CVC) of SFIFS Josephson junctions (S = bulk superconductor, F = metallic ferromagnet, I = insulating barrier) with weak ferromagnetic

• interlayers, which we attribute to DOS energy dependencies in the case of small exchange fields in the F layers. Keywords: current–voltage characteristics; Josephson junctions; proximity effect, superconductivity; superconductor/ferromagnet hybrid nanostructures; Introduction It is well known that

• circuits [47], and as injectors in superconductor–ferromagnetic transistors [81][82][83][84], which can be used as amplifiers for memory, digital, and RF applications. In this work we study the current–voltage characteristics of a SFIFS junction as shown below in Figure 1. We present a quantitative model

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

• measurement of the lower (first) critical field of three different superconductors, high-Tc cuprate YBa2Cu3O7−δ (YBCO), and iron-based superconductors is performed, as the lower critical field is a fundamental parameter to characterize a type-II superconductor. Sample cooling to a target temperature below Tc

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

• superconductor with a superconductivity transition temperature (Tc) of 5.5 K, which is higher than previously reported results [22]. As a result of its electronic structure, titanium monoxide nanoparticles find further application in heterogeneous catalysis, e.g., for the hydrogenation of styrene [1]. Here we

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

• , 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

• contact spectroscopy [16], has a 90% polarization of the conduction band, we have chosen as a drawing layer for LRTC the HA Co2Cr1−xFexAly with a spin polarization of the conduction band of ≥70% [17] and instead of MoGe as an S layer we have used the elemental superconductor Pb. Sample Preparation and

Synthesis and characterization of quaternary La(Sr)S–TaS₂ misfit-layered nanotubes

• Marco Serra,
• Erumpukuthickal Ashokkumar Anumol,
• Dalit Stolovas,
• Iddo Pinkas,
• Ernesto Joselevich,
• Reshef Tenne,
• Andrey Enyashin and
• Francis Leonard Deepak

Beilstein J. Nanotechnol. 2019, 10, 1112–1124, doi:10.3762/bjnano.10.111

• [46]. Finally, the compound SrTa2S5 with hexagonal structure, which can be possibly described as SrS–(TaS2)2 MLC, was found to exhibit a transition to a superconductor state at 3.16 K. [47]. A few authors suggested that increasing the charge transfer from the MX unit to the TX2 suppresses the charge

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

• alignment can be controlled with a magnetic field of only several tens of Oersted. Keywords: cryogenic computing; neutron scattering; spin valve; superconducting spintronics; Findings Superconductor digital devices have attracted growing attention due to their unique energy efficiency and performance [1

• magnetic state can be switched between parallel and antiparallel directions of the magnetization vectors of the F layers [7]. The use of a thin superconducting layer (s) as a spacer instead of an N layer may lead to enhancement of the spin-valve effect due to the proximity of the thick superconductor banks

• and the thin superconductor spacers (see, e.g., [8]). To check this hypothesis we calculated the critical current of S/F/s/F/S and S/F/N/F/S Josephson junctions (Figure 1). The calculations were performed in the framework of the Usadel equation [17] with Kupriyanov–Lukichev conditions [18] in an

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

• Zoltán Scherübl,
• András Pályi and
• Szabolcs Csonka

Beilstein J. Nanotechnol. 2019, 10, 363–378, doi:10.3762/bjnano.10.36

• superconductor tunnel-coupled to the dots, often called a Cooper-pair splitter. We study the three special cases where one of the three non-local mechanisms dominates, and calculate measurable ground-state properties, as well as the zero-bias and finite-bias differential conductance characterizing electron

• weakly tunnel-coupled to a superconductor in a QD–SC–QD geometry [25][26][27][28][29][30][31][32]. The QD–SC–QD setup serves also as the basic building block of the poor man’s Majorana setup [8] and the Majorana chain [9]. Strong tunnel coupling between a QD and a SC leads to the formation of Andreev

• between the dots is due to the proximity of the superconductor (CAR or EC dominates over IT), or not (IT dominated). Finite-bias conductance Here, first we show how the presence non-local couplings affect the finite-bias transport for a general case, then we show that CAR and EC provide different

Interaction-induced zero-energy pinning and quantum dot formation in Majorana nanowires

• Samuel D. Escribano,
• Alfredo Levy Yeyati and
• Elsa Prada

Beilstein J. Nanotechnol. 2018, 9, 2171–2180, doi:10.3762/bjnano.9.203

• features are observed in recent experiments on the detection of Majoranas and could thus help to properly characterize them. Keywords: hybrid superconductor–semiconductor nanowires; interactions; Majorana bound states; quantum dots; Introduction Semiconducting nanowires with strong spin–orbit interaction

• -length wire posses a finite charge, typically distributed uniformly along the wire [34], which can be susceptible to electrostatic interactions with the surrounding medium. We considered the case of a grounded parent superconductor, thus avoiding the effect of a charging energy associated to the Cooper

• Majorana overlap, which is a measurement of the degree of non-locality of the two Majorana wave functions, mostly depends on the length of the nanowire (and to a lesser extent on other parameters, such as the induced superconductor gap and the Rashba coupling), but it is not necessarily correlated to the

Increasing the performance of a superconducting spin valve using a Heusler alloy

• Andrey A. Kamashev,
• Aidar A. Validov,
• Joachim Schumann,
• Vladislav Kataev,
• Bernd Büchner,
• Yakov V. Fominov and
• Ilgiz A. Garifullin

Beilstein J. Nanotechnol. 2018, 9, 1764–1769, doi:10.3762/bjnano.9.167

• Heusler film as compared to Fe. This enables to approach an almost ideal theoretical magnitude of the switching in the Heusler-based multilayer with a F2 layer thickness of ca. 1 nm. Keywords: ferromagnet; proximity effect; spin valve; superconductor; Introduction Historically, the first concept to

• manipulate the transition temperature Tc of a superconductor by sandwiching it between two ferromagnetic insulators was thought of by de Gennes [1]. Regarding the case of metallic ferromagnets, the physical principle of a superconducting spin valve (SSV) is based on the idea proposed by Oh et al. in 1997 [2

A zero-dimensional topologically nontrivial state in a superconducting quantum dot

• Pasquale Marra,
• Alessandro Braggio and
• Roberta Citro

Beilstein J. Nanotechnol. 2018, 9, 1705–1714, doi:10.3762/bjnano.9.162

• spectrum. Here, we show that a quantum dot coupled with two superconducting leads can realize a nontrivial zero-dimensional topological superconductor with broken time-reversal symmetry, which corresponds to the finite size limit of the one-dimensional topological superconductor. Topological phase

• [14][15][16][17][18][19][20]. The simplest realization of a topological superconductor is the well-known Kitaev chain [3], which can be implemented in a one-dimensional system proximized by a conventional superconductor in the presence of a magnetic field and spin–orbit coupling [21][22][23][24][25

• one-dimensional (1D) topological superconductor with broken time-reversal and chiral symmetries. In this limit, the system turns zero-dimensional (0D), i.e., its energy spectrum is a finite set of discrete energy levels. This 0D superconductor exhibits topological phase transitions that correspond to

Josephson effect in junctions of conventional and topological superconductors

• Alex Zazunov,
• Albert Iks,
• Miguel Alvarado,
• Alfredo Levy Yeyati and
• Reinhold Egger

Beilstein J. Nanotechnol. 2018, 9, 1659–1676, doi:10.3762/bjnano.9.158

• , Universidad Autónoma de Madrid, E-28049 Madrid, Spain 10.3762/bjnano.9.158 Abstract We present a theoretical analysis of the equilibrium Josephson current-phase relation in hybrid devices made of conventional s-wave spin-singlet superconductors (S) and topological superconductor (TS) wires featuring Majorana

• end states. Using Green’s function techniques, the topological superconductor is alternatively described by the low-energy continuum limit of a Kitaev chain or by a more microscopic spinful nanowire model. We show that for the simplest S–TS tunnel junction, only the s-wave pairing correlations in a

• ] have pointed out that the physics of the Kitaev chain could be realized in spin–orbit coupled nanowires with a magnetic Zeeman field and in the proximity to a nearby s-wave superconductor. The spinful nanowire model of references [2][3] indeed features p-wave pairing correlations for appropriately

Robust topological phase in proximitized core–shell nanowires coupled to multiple superconductors

• Tudor D. Stanescu,
• Anna Sitek and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1512–1526, doi:10.3762/bjnano.9.142

• promising involving semiconductor-superconductor hybrid systems [5][6][7][8][9]. The basic idea [10][11][12][13] is to proximity-couple a semiconductor nanowire with strong Rashba-type spin-orbit coupling (e.g., InSb or InAs) to a standard s-type superconductor (e.g., NbTiN or Al) in the presence of a

• topological character of these modes endows them with robustness against perturbations that do not close the superconductor gap, e.g., weak interactions, wire bending, a certain amount of disorder, etc. The most straightforward experimental signature of a Majorana mode is a zero-bias conductance peak that is

• wire, but no clear evidence of a phase transition to the topological phase, as revealed by the closing of the bulk quasiparticle gap [10][11][12][13], or evidence of correlated features at the opposite ends of the wire [25]. Ideally, the MZMs are hosted by a one-dimensional (1D) p-wave superconductor