Current-induced mechanical torque in chiral molecular rotors

• Richard Korytár and
• Ferdinand Evers

Beilstein J. Nanotechnol. 2023, 14, 711–721, doi:10.3762/bjnano.14.57

• unidirectional rotation in the STM setup requires a degree of symmetry breaking. There are two typical situations, that is, either the molecule by itself exhibits a handedness (chirality) or chirality is imposed by the geometry of the molecular junction [6][10]. The purpose of this article is to provide a

Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field

• Levente Máthé and
• Ioan Grosu

Beilstein J. Nanotechnol. 2020, 11, 225–239, doi:10.3762/bjnano.11.17

• be realized by a molecular junction or a single quantum dot (QD) or many QDs in a particular arrangement coupled to charge reservoirs by metallic [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], ferromagnetic [32][33][34][35] or graphene electrodes [36][37][38

Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower

• Rouzhaji Tuerhong,
• Mauro Boero and
• Jean-Pierre Bucher

Beilstein J. Nanotechnol. 2019, 10, 1243–1250, doi:10.3762/bjnano.10.124

• to study, with atomic resolution, the coupling of the tunneling electrons to other elementary excitations such as vibrations, plasmons and spins [5][6][7][8]. Furthermore, a molecular junction in STM can serve as a reliable and controllable model system for the study of a single molecule in a way

• reversible molecule transfer process between the tip and the surface indicates that the MnPc molecule is attached to the STM tip apex and not to any other site on the tip. Vibration-mediated electron transport in a molecular junction In the following, the electron transport through a MnPc molecule suspended

• tunneling through excitation of molecular vibration modes. Parameter-dependent transport in a molecular junction In order to gain additional information about the kinetics of carriers not contained in the current–voltage characteristics we want to evaluate the impact of the zero-bias peak on the thermopower

Electronic conduction during the formation stages of a single-molecule junction

• Atindra Nath Pal,
• Tal Klein,
• Ayelet Vilan and
• Oren Tal

Beilstein J. Nanotechnol. 2018, 9, 1471–1477, doi:10.3762/bjnano.9.138

• and examine the interplay between these two conductance pathways. Furthermore, the role of this structure in the formation of single-molecule junctions is studied. Our findings reveal the conductance and structural properties of premature molecular junction configurations and uncover the different

• molecules suggests the formation of a molecular junction in parallel to a metal atomic junction or, alternatively, the formation of a metal junction (e.g., a diatomic contact) with modified conduction due to adsorbed molecules. Individual traces (e.g., Figure 1c, inset) show that the 1.3 G0 plateaus are

• spectroscopy [11][12][13][14] can offer valuable information about the structure of the combined metallic and molecular junctions. When an applied voltage (V) across a molecular junction exceeds the energy (in eV) of a certain molecular vibration mode, some of the transmitted electrons lose energy to excite

Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions

• Youngsang Kim,
• Safa G. Bahoosh,
• Dmytro Sysoiev,
• Thomas Huhn,
• Fabian Pauly and
• Elke Scheer

Beilstein J. Nanotechnol. 2017, 8, 2606–2614, doi:10.3762/bjnano.8.261

• : inelastic electron tunneling spectroscopy; molecular junction; photochromic; single molecule; Introduction Molecular junctions hold promise for the realization of novel miniaturized electronic circuits [1][2][3][4][5][6] as well as for thermoelectric energy conversion devices [7][8][9][10]. Optoelectronic

Adsorbate-driven cooling of carbene-based molecular junctions

• Giuseppe Foti and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 2060–2068, doi:10.3762/bjnano.8.206

• stability under bias of single-molecule circuits. Keywords: adsorbate; carbene; current-induced heating and cooling; molecular junction; vibrations; Introduction Molecular electronics has experienced a remarkable progress since its first proposal [1]. Theoretical as well as experimental advances have made

• analyzing the effect of adsorbates is particularly relevant. Here we address this issue by investigating the effect on the current-induced heat exchange of a molecular species adsorbed in the vicinity of the molecular junction. As we show in this paper, the presence of adsorbates not bonded directly to the

• molecular junction in the low bias regime. HCD mediated by adsorbate states As previously mentioned, the NH2 adsorbate introduces additional features in the low-energy CA DOS (blue line in Figure 2a). The position and bias dependence of these states can influence the heating and cooling dynamics of the

Spin-dependent transport and functional design in organic ferromagnetic devices

• Guichao Hu,
• Shijie Xie,
• Chuankui Wang and
• Carsten Timm

Beilstein J. Nanotechnol. 2017, 8, 1919–1931, doi:10.3762/bjnano.8.192

• , namely an inversion of the rectification, may happen. This has been discussed in detail in [59]. Note that the concept of SC rectification reviewed here is based on spin-polarized charge transport. This phenomenon has also been reported in a molecular junction with one ferromagnetic and one nonmagnetic

Role of solvents in the electronic transport properties of single-molecule junctions

• Katharina Luka-Guth,
• Sebastian Hambsch,
• Andreas Bloch,
• Philipp Ehrenreich,
• Bernd Michael Briechle,
• Filip Kilibarda,
• Torsten Sendler,
• Dmytro Sysoiev,
• Thomas Huhn,
• Artur Erbe and
• Elke Scheer

Beilstein J. Nanotechnol. 2016, 7, 1055–1067, doi:10.3762/bjnano.7.99

• level alignment [9][10][13][21]. In general, a molecular junction is not formed in all of the breaking curves, but the majority of curves show smooth or noisy distance dependence. These curves are interpreted as tunnelling through the solvent that has no influence on the apparent conductance values of

Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations

• Alberto Nocera,
• Carmine Antonio Perroni,
• Vincenzo Marigliano Ramaglia and
• Vittorio Cataudella

Beilstein J. Nanotechnol. 2016, 7, 439–464, doi:10.3762/bjnano.7.39

• molecular junction will be analyzed. In Equation 6, the coupling between the displacement and a phonon q in the lead α is given by the elastic constant Cq,α. In order to characterize this interaction, one introduces the spectral density J(ω): with M being the mass of the lead atoms and the frequency

• ). In this case, the dynamical correction due to the adiabatic approach gives a substantial broadening of the resonance peak that is shifted by the polaronic effect [76]. We devote the rest of this section to the discussion of the thermoelectrical properties of a molecular junction in the linear

Invariance of molecular charge transport upon changes of extended molecule size and several related issues

• Ioan Bâldea

Beilstein J. Nanotechnol. 2016, 7, 418–431, doi:10.3762/bjnano.7.37

• , characterizing the molecule–electrode couplings (x = L,R). Within the Landauer approach, which provides a general framework to describe the molecular transport within the elastic, uncorrelated transport approximation, the (steady-state) current I through a molecular junction is obtained by integrating the

• molecular junction considered below, which is schematically depicted in Figure 1, reads In the equations above, al (), br (), and cμ () stand for annihilation (creation) operators for electrons in the left and right electrodes and in the “small” molecule, respectively. Restricting to spin-independent

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• −6G0, Figure 14c,d) [126]. Ab initio charge-transport calculations through the molecular junction based on pyridine-terminated tripodal platforms 34 fully matched with the experimental results and revealed that the electron-deficient π* orbitals of the pyridine anchor subunits directly interact with

• the gold electrode and result in a robust molecular junction via the three pyridine units, where the LUMO dominates the electron transport via π-channel hybridization (Figure 14a,b). Lindsey, Bocian and co-workers synthetized several redox-active molecules bearing a tether composed of a tripodal

Effects of electronic coupling and electrostatic potential on charge transport in carbon-based molecular electronic junctions

• Richard L. McCreery

Beilstein J. Nanotechnol. 2016, 7, 32–46, doi:10.3762/bjnano.7.4

• difficult to calculate accurately, it does provide a basis for the “vacuum level shift” observed in many experiments, including transport and ultraviolet photoelectron spectroscopy of molecular layers on conductors. Keywords: molecular junction electron transport density functional theory molecular devices

• possibility of electronic components that are smaller than existing transistors or diodes, have unusual properties not possible with conventional semiconductors, use less power, or are cheaper than existing microelectronics. A basic element of Molecular Electronics is the “molecular junction (MJ)” consisting

• aspects of junction behavior are attributable to the unique carbon–carbon bonding at one or both contacts of the molecular junction. A simple model based on single molecules and oligomers bonded to small graphene fragments representing the sp2 carbon contacts provides insights into how electronic

Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

• Riccardo Frisenda,
• Mickael L. Perrin and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 2477–2484, doi:10.3762/bjnano.6.257

• electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of

• . Multiple junction configurations are observed with distinct IETS spectra. In a second experiment, we monitor the IETS spectrum of a molecular junction as a function of the electrode displacement. The IETS spectra recorded at different locations display large variations among each other. A comparison with

• in Figure 2a shows the typical signal of an empty junction, in which the conductance after the rupture of the last gold contact decreases exponentially with distance. This is a signature of vacuum tunneling between two metallic electrodes. Once a molecular junction is formed (junction 1, right

High electronic couplings of single mesitylene molecular junctions

• Yuki Komoto,
• Shintaro Fujii,
• Tomoaki Nishino and
• Manabu Kiguchi

Beilstein J. Nanotechnol. 2015, 6, 2431–2437, doi:10.3762/bjnano.6.251

• electrode perpendicular to the charge transport direction and (ii) mesitylene has tilted from the perpendicular orientation. Keywords: break junction; charge transport; mesitylene; single molecular junction; scanning tunnelling microscopy (STM); Introduction Along with increasing interests in molecular

• electronics on the single molecular scale [1], much efforts have been devoted to understand charge transport in a single molecular junction, in which a single molecule is wired to two metal electrodes. In recent years single molecular junctions with electronic functionalities such as diodes [2][3][4][5][6][7

• , electronic conductance of the single molecular junction can be described by two parameters of (i) the electronic coupling between electrodes and molecule and (ii) the relative energy level alignment of the conduction orbital of molecule with respect to the Fermi level of the metal electrodes. By fitting the

Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

• David Rakhmilevitch and
• Oren Tal

Beilstein J. Nanotechnol. 2015, 6, 2417–2422, doi:10.3762/bjnano.6.249

• presence of electron–vibration interaction, this picture can change considerably. At a sufficiently high voltage the injected electrons have the necessary energy to excite a certain vibration mode of the molecular junction (). This inelastic process promotes a vibration-mediated Kondo transport for which

• in a molecular junction. Recently, vibration-mediated Kondo transport was demonstrated in junctions consisting of a copper–phthalocyanine (CuPc; Figure 1b) molecule suspended between silver (Ag) electrodes [23]. In the current work we use similar junctions realized in a break junction setup, to

• activation can be distinguished. This analysis sheds light on the different parameters that affect vibration-mediated Kondo transport. As a starting point we briefly mention the relevant information found by former analysis of the Ag/CuPc molecular junction [23]. Differential conductance measurements

Thermoelectricity in molecular junctions with harmonic and anharmonic modes

• Bijay Kumar Agarwalla,
• Jian-Hua Jiang and
• Dvira Segal

Beilstein J. Nanotechnol. 2015, 6, 2129–2139, doi:10.3762/bjnano.6.218

• bias voltage [6][7][8]. The system is also referred to as the “dimer molecular junction” [9], or an “open spin–boson model” [10] (where the spin here represents the D and A states, the bosons correspond to the molecular vibrational modes, and the system is open, i.e., coupled to metal leads). It was

• Fermi–Dirac distribution function of the ν = L,R lead. The properties of the molecular junction are embedded within the spectral density functions, peaked around the molecular electronic energies εd,a with the broadening ΓL,R satisfying, e.g., , These expressions are reached through the diagonalization

• Figure 6 we simulate the current–voltage characteristics and the resulting efficiency of the D–A junction beyond linear response, by directly applying Equation 13. As discussed in previous investigations [6][7][8], the molecular junction may break down far from equilibrium due to the development of

Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring

• Yuya Kitaguchi,
• Satoru Habuka,
• Hiroshi Okuyama,
• Shinichiro Hatta,
• Tetsuya Aruga,
• Thomas Frederiksen,
• Magnus Paulsson and
• Hiromu Ueba

Beilstein J. Nanotechnol. 2015, 6, 2088–2095, doi:10.3762/bjnano.6.213

• imaging the area. Also we can repeat the lift and release without changing the condition of the tip apex. Thus, the molecular junction can be reversibly switched by mechanical motion of a phenyl ring. As shown in [12] this switching mechanism is also supported by the calculated potential energy landscape

• ascribed to the sulfur atom (Figure 3a). The local structure is similar with that of PhO with the phenyl ring oriented along [001] and the sulfur atom bonded to the short-bridge site [13]. The controlled switching of the molecular junction is feasible with PhS as well as PhO, and the conductance values for

• the tip fixed over the molecule, during which the tunnel current was recorded (red lines). The on-state (lifted) is favorable at a negative sample bias, whereas the off-state (flat) is favorable at a positive bias. (b) Repeated switching of the molecular junction by using a sequence of voltage pulses

Conductance through single biphenyl molecules: symmetric and asymmetric coupling to electrodes

• Karthiga Kanthasamy and
• Herbert Pfnür

Beilstein J. Nanotechnol. 2015, 6, 1690–1697, doi:10.3762/bjnano.6.171

• , diodes and logic switches [1]. Two decades after the proposal from Aviram and Ratner describing the molecular junction as p-n diodes [2] the experimental research in the field of molecular electronics [3] emerged. Even today, our understanding of the fundamental properties and charge transport mechanism

• (up to few Å displacement), due to bond reformation or thermodynamic stability of the molecular junction [44][45] as already explained. We stopped at these particular positions and recorded multiple sweeps of current versus voltage. Some of these positions turned out to be stable over several hours

• small asymmetries seen in Figure 8, the difference in the two coupling parameters is only few mV, which was also observed in the asymmetric Au–NH2–B–SH–Au molecular junction [6]. According to Equation 1, for small voltages a square root dependence of the coupling Γ on conductance can derived , if E0 is

Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

• Riccardo Frisenda,
• Simge Tarkuç,
• Elena Galán,
• Mickael L. Perrin,
• Rienk Eelkema,
• Ferdinand C. Grozema and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 1558–1567, doi:10.3762/bjnano.6.159

• single-level model allows to quantify the electronic coupling between the various molecules and the electrodes and the injection barrier [33]. Additionally, we have performed self-breaking measurements, in which we measure the low-bias conductance of a molecular junction as a function of time until the

• of the two outer gold layers. Every ten steps (40 pm) we calculate the transmission through the molecular junction using non-equilibrium Green’s function (NEGF) formalism by connecting the outer gold layer to wide-band limit electrodes. To account for well-known problems in the DFT eigenvalues we

• , where the color indicates the probability for a value of conductance to appear at a certain displacement during the stretch of the junction. Since the histograms are built without data selection they contain both breaking traces measured on a molecular junction, showing a characteristic plateau in

Alternative types of molecule-decorated atomic chains in Au–CO–Au single-molecule junctions

• Zoltán Balogh,
• Péter Makk and
• András Halbritter

Beilstein J. Nanotechnol. 2015, 6, 1369–1376, doi:10.3762/bjnano.6.141

• interpretation of the M1 configuration as a parallel CO molecular junction. As an alternative we consider the so-called atop geometry reported in [29][30], where the CO molecule is not wedged in between two Au atoms, but it binds to the side of a single Au atom of a gold atomic chain (see Figure 5c1). This

Can molecular projected density of states (PDOS) be systematically used in electronic conductance analysis?

• Tonatiuh Rangel,
• Gian-Marco Rignanese and
• Valerio Olevano

Beilstein J. Nanotechnol. 2015, 6, 1247–1259, doi:10.3762/bjnano.6.128

• quantum transport is needed in order to fully understand the behavior of the molecular junction as an electronic device. Thus, it is important to establish a relationship between the conductance and the electronic structure, for example, by determining the main constituents influencing the absolute value

• molecular junction is modeled by a central region (C) connected to two semi-infinite leads (left (L) and right (R)). Its conductance as a function of the energy of the injected electrons, , is given by the Landauer formula: M(ε) is the number of modes at a given energy, ε, and T(ε) is their transmittance

• conductance changes with varying chemical composition or with the atomic structure of the central molecule. Furthermore, when looking at the overall representation of the molecular junction, the central molecule appears as a “bottleneck” in the stream of electrons flowing from one lead to the other. For this

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• molecules similar to 1 with two pyridyl terminal groups exhibit two conductance values, which have been attributed to two distinct binding geometries in the molecular junction [105]. The lower of these two conductance values has been assigned to the simplest N–Au binding of the molecular normal to a flat

• refers to the estimated separation at which the molecular junction cleaves during an I(s) retraction experiment and it can be compared to the length of the molecule. The break-off distance obtained from Figure 9c (1.65 ± 0.2 nm) is in good agreement with the length of the molecule (1.64 nm) determined

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

• Chris Hellenthal,
• Kai Sotthewes,
• Martin H. Siekman,
• E. Stefan Kooij and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2015, 6, 1116–1124, doi:10.3762/bjnano.6.113

• properties of the molecule under consideration, and extensive research has been performed on numerous different systems [20][21][22][23][24]. In 2004, Engelkes et al. determined the resistance of a molecular junction as a function of the length of the used molecule [25]. Additionally, the effective mass of

Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

• Kai Braun,
• Xiao Wang,
• Andreas M. Kern,
• Hilmar Adler,
• Heiko Peisert,
• Thomas Chassé,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2015, 6, 1100–1106, doi:10.3762/bjnano.6.111

• superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip) of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• temperature range (T < 233 K) but no discontinuity is observed in the junction properties at this particular temperature. The ac modulation amplitude VAC was set at 20 mV. The capacitance (4.5 pF) of the empty Teflon cell in parallel with the molecular junction was subtracted to obtain Cm. At high frequencies