Modulated critical currents of spin-transfer torque-induced resistance changes in NiCu/Cu multilayered nanowires

• Mengqi Fu,
• Roman Hartmann,
• Julian Braun,
• Sergej Andreev,
• Torsten Pietsch and
• Elke Scheer

Beilstein J. Nanotechnol. 2024, 15, 360–366, doi:10.3762/bjnano.15.32

• coercivity as well as the angular momentum of NiCu become smaller when the thickness is reduced to several to tens of nanometers [22][23][24][25]. Thus, the magnetic field to reverse the magnetization of the different magnetic layers within one nanowire can vary significantly. In addition, the different

• top of the nanowires are flipped one by one under small magnetic fields; thus, more than one free layer can exist in the measured device [8][30][31][32]. Since Ic+, Ic−, and Imicro are closely related to the properties (e.g., thickness, volume, coercivity, and angular momentum) of the free layers and

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

• has been great endeavor to engineer molecular rotors operated by an electrical current. A frequently met operation principle is the transfer of angular momentum taken from the incident flux. In this paper, we present an alternative driving agent that works also in situations where angular momentum of

• ). The motion of the particle along the molecule obeys Lagrangian dynamics. The wire can rotate around a given axis with angle ϑ. The torque driving the rotation is provided by the back action of moving particle. In the absence of a potential V(ϑ), angular momentum is conserved. The main outcome of this

• work is that the wire rotates even if the net transfer of angular momentum of the transmitted particles is zero. The operation principle is that the particle exerts a torque when entering and leaving the molecular wire. Even if both exactly compensate, the wire rotates while the particle travels along

Ultrafast signatures of magnetic inhomogeneity in Pd_1−xFe_x (x ≤ 0.08) epitaxial thin films

• Andrey V. Petrov,
• Sergey I. Nikitin,
• Lenar R. Tagirov,
• Amir I. Gumarov,
• Igor V. Yanilkin and
• Roman V. Yusupov

Beilstein J. Nanotechnol. 2022, 13, 836–844, doi:10.3762/bjnano.13.74

• matter of intense discussion in past decades [38][39][40][41][42][43]. An additional demagnetization component with a characteristic time of ≈10 ps requires the presence of a paramagnetic fraction in the material. However, the transfer of the angular momentum between the paramagnetic and ferromagnetic

• fractions by highly mobile s and p electrons (which occurs due to the s–d interaction [40]) should only increase the rate of photoinduced demagnetization on a subpicosecond scale. This mechanism was justified to explain the ultrafast (subpicosecond) transfer of the angular momentum in F/N heterostructures

Experimental and theoretical study of field-dependent spin splitting at ferromagnetic insulator–superconductor interfaces

• Peter Machon,
• Michael J. Wolf,
• Detlef Beckmann and
• Wolfgang Belzig

Beilstein J. Nanotechnol. 2022, 13, 682–688, doi:10.3762/bjnano.13.60

• during sample transfer between our two fabrication steps. Lacking a microscopic model, we have attempted to fit the field dependence of δφ with a Brillouin function. The fit is shown as a line in Figure 5b. It is in reasonable agreement with the data up to about 0.6 T, with an effective angular momentum

Influence of magnetic domain walls on all-optical magnetic toggle switching in a ferrimagnetic GdFe film

• Rahil Hosseinifar,
• Evangelos Golias,
• Ivar Kumberg,
• Quentin Guillet,
• Karl Frischmuth,
• Sangeeta Thakur,
• Mario Fix,
• Manfred Albrecht,
• Florian Kronast and
• Wolfgang Kuch

Beilstein J. Nanotechnol. 2022, 13, 74–81, doi:10.3762/bjnano.13.5

• polarization [4]. This all-optical toggle switching is explained by the different speeds of demagnetization of Gd and the 3d metal in the ferrimagnetic alloy or in bilayers upon exposure to the laser pulse, together with the conservation of angular momentum during the laser-induced demagnetization [16][17][18

•  2), that is, well below and above the magnetization and angular momentum compensation temperatures. Their kinetics, however, may well depend on temperature. We mentioned already that the boundaries between switched and unswitched regions of the sample are expected to be smooth and follow a line of

• directed, would be into the direction of higher fluence, not into the direction of lower fluence. Domain-wall motion towards the higher temperature in a temperature gradient can be explained by entropy [23][24] or conservation of angular momentum during the transmission of magnons driven by the temperature

Effect of lubricants on the rotational transmission between solid-state gears

• Huang-Hsiang Lin,
• Jonathan Heinze,
• Alexander Croy,
• Rafael Gutiérrez and
• Gianaurelio Cuniberti

Beilstein J. Nanotechnol. 2022, 13, 54–62, doi:10.3762/bjnano.13.3

• , respectively. The blue dashed lines are trajectories of the rotation angle of the second gear corresponding to the case without lubricants, which exhibit oscillations on top of a linearly increasing trend. One can imagine that when the angular momentum is transferred from the first gear to the second one, the

• rotation closer to the case of rigid bodies. The underlying reason for this behavior is the tendency of the lubricant molecules to fill the gap between gears and to provide a medium for angular momentum transfer at all times, which stabilizes the motion of the second gear. However, more energy is needed to

• dependence From the previous section, we know that the lubricants can assist the transmission of angular momentum between gears. One might still wonder if the angular velocity of the first gear plays any role. Therefore, we performed MD simulations with different initial angular velocities ω = π, 2π and 4π

Recent progress in magnetic applications for micro- and nanorobots

• Ke Xu,
• Shuang Xu and
• Fanan Wei

Beilstein J. Nanotechnol. 2021, 12, 744–755, doi:10.3762/bjnano.12.58

• according to the alignment and response of magnetic dipoles, magnetic materials can be divided into diamagnetic, paramagnetic [31], ferromagnetic, ferrimagnetic, and antiferromagnetic. Diamagnetism of the material can be attributed to the orbital angular momentum, which is a phenomenon in which

• nanoparticles gain magnetization against an applied external magnetic field. Paramagnetism is caused by spin angular momentum (i.e., spin magnetic moment). Under the action of an external magnetic field, the initially disordered magnetic moments will be reoriented, thereby exhibiting paramagnetism, while other

Kondo effects in small-bandgap carbon nanotube quantum dots

• Patryk Florków,
• Damian Krychowski and
• Stanisław Lipiński

Beilstein J. Nanotechnol. 2020, 11, 1873–1890, doi:10.3762/bjnano.11.169

• introduces parallel or antiparallel alignments of spin and angular momentum. The energy of SO coupling is comparable to the energy scale of the Kondo effect. Therefore, taking this perturbation into account is important when analyzing many-body effects in these systems. Several interesting papers have been

The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

• Hajar Jalili,
• Bagher Aslibeiki,
• Ali Ghotbi Varzaneh and
• Volodymyr A. Chernenko

Beilstein J. Nanotechnol. 2019, 10, 1348–1359, doi:10.3762/bjnano.10.133

• increasing magnetic anisotropy with increasing cobalt content. This is due to the gradual occupation of the octahedral sites by cobalt ions and the stronger LS coupling originating from their strong orbital angular momentum [37][38]. The drop of anisotropy in the x = 0.8 sample might be due to the decrease

Fabrication of phase masks from amorphous carbon thin films for electron-beam shaping

• Lukas Grünewald,
• Dagmar Gerthsen and
• Simon Hettler

Beilstein J. Nanotechnol. 2019, 10, 1290–1302, doi:10.3762/bjnano.10.128

• ; Bessel beam; electron-beam shaping; nanofabrication; vortex beam; Introduction The possibility to shape electron beams has gained much interest since the first observation of electron vortex beams, i.e., beams that carry a defined orbital angular momentum [1][2][3]. Various other beam shapes, e.g., non

• (VBs) are of great interest due to their well-defined orbital angular momentum (OAM) with the topological charge l and the Dirac constant The phase of a VB varies azimuthally upon propagation, where l is equal to the number of turns in the wave front per wavelength [27]. In the center of a VB exists

Bidirectional biomimetic flow sensing with antiparallel and curved artificial hair sensors

• Claudio Abels,
• Antonio Qualtieri,
• Toni Lober,
• Alessandro Mariotti,
• Lily D. Chambers,
• Massimo De Vittorio,
• William M. Megill and
• Francesco Rizzi

Beilstein J. Nanotechnol. 2019, 10, 32–46, doi:10.3762/bjnano.10.4

• conditioning applications with variable air flow speeds, ranging between a few and 40 m s−1. A first real-world case study with our flow sensor platform was designed and conducted by the Institute of Air Handling and Refrigeration in Dresden (Germany), which aimed at detecting angular momentum in industrial

• air ducts for controlling the speed of contra-rotating axial fans. A given technical problem of axial fans is the emergence of unavoidable swirl in the wake flow with high peripheral speeds. While contra-rotating axial fans already reduce the swirl in the wake flow [51], detecting angular momentum in

Influence of the thickness of an antiferromagnetic IrMn layer on the static and dynamic magnetization of weakly coupled CoFeB/IrMn/CoFeB trilayers

• Deepika Jhajhria,
• Dinesh K. Pandya and
• Sujeet Chaudhary

Beilstein J. Nanotechnol. 2018, 9, 2198–2208, doi:10.3762/bjnano.9.206

• magnetoresistance [7], inverse spin Hall effect [8] and spin Seebeck effect [9][10] have already been reported in AF materials. Transfer of spin angular momentum presents one of the promising ways to control the magnetic properties of FM thin films [11]. However, little is known about spin transport in AF materials

• nm thickness of the IrMn layer. According to the theoretical calculations [34], the intrinsic magnetic ordering of the AF materials can itself sustain propagating spin excitations thereby potentially allowing the transport of spin angular momentum. These spin excitations exist in the form of AF

• least four-magnon interaction as the two-magnon interaction is prohibited [35][36]. Therefore, we argue that there can be another alternative mechanism for the transfer of spin angular momentum in the IrMn layer based on the propagation of AF spin excitations. This can conceptually explain the long

Excitation of nonradiating magnetic anapole states with azimuthally polarized vector beams

• Aristeidis G. Lamprianidis and
• Andrey E. Miroshnichenko

Beilstein J. Nanotechnol. 2018, 9, 1478–1490, doi:10.3762/bjnano.9.139

• coordinates, with respect to the coordinate system of the focused beam, is given by the vector d(R,Θ,Φ) = r− r1. where are the VSHs. The indicator α acquires the names M,N for the TE (magnetic) and TM (electric) VSHs respectively, the index ν stands for the angular momentum quantum number, which takes the

• into Fourier series with respect to the azimuthal angle γ. So, due to its 2π-periodicity, we have: , which is an expansion into modes with different orbital angular momentum m. Then, we can also perform the integration over the azimuthal angle analytically. This yields the simplified formula of

• condition . This implies that the orbital angular momentum m of the input beams before their focusing is bequeathed to the azimuthal quantum number of the multipolar expansion of the focused beams with respect to such a reference frame. This would mean, for example, that a focused beam with m = 3 would bear

Circular dichroism of chiral Majorana states

• Javier Osca and
• Llorenç Serra

Beilstein J. Nanotechnol. 2018, 9, 1194–1199, doi:10.3762/bjnano.9.110

• negative. In the limit of a long 2D ribbon there is a preferred CD sign, depending on the magnetic field orientation. For a disc geometry the generalized angular momentum Jz becomes a good quantum number. Then, the combination of circular and particle–hole symmetries in a disc causes a vanishing absorption

• states at low energy arrange themselves on a line (a chiral band) when plotted as a function of the z-component of the angular momentum. For positive ΔB the angular momentum decreases with increasing energy, causing empty (particle) states to have negative values of , while occupied (hole) states have

• geometry Jz is not a good quantum number and, therefore, there are states with mixed angular momentum. We have performed calculations in a circular geometry confirming this interpretation. Therefore, quasiparticle scattering by the corners plays a nontrivial role on the absorption by chiral edge states

An implementation of spin–orbit coupling for band structure calculations with Gaussian basis sets: Two-dimensional topological crystals of Sb and Bi

• Sahar Pakdel,
• Mahdi Pourfath and
• J. J. Palacios

Beilstein J. Nanotechnol. 2018, 9, 1015–1023, doi:10.3762/bjnano.9.94

• part, yield to lowest order a SOC correction of the form (see, e.g., [31] for a nice overview of a fairly extensive topic) which mixes orbital angular momentum (m) and spin (σ) quantum numbers. Since the angular and radial parts of the wave functions are orthogonal, SOC matrix elements between

Valley-selective directional emission from a transition-metal dichalcogenide monolayer mediated by a plasmonic nanoantenna

• Haitao Chen,
• Mingkai Liu,
• Lei Xu and
• Dragomir N. Neshev

Beilstein J. Nanotechnol. 2018, 9, 780–788, doi:10.3762/bjnano.9.71

• ) measurements [12][13][14], where the chirality of the PL emission is the same as the pumping light, since different valleys are addressed by the angular momentum of the excitation. Hence, one can switch the chirality of the PL emission from left to the right (and the other way around) by changing the

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• observed using a light microscope [125][126]. Finally, since the 1O2 species possess paramagnetic properties caused by the orbital angular momentum, they can be quantified by direct ESR detection [127]. Therefore, an ESR spectrometer with a microwave frequency of about 9 GHz (X-band) could be used to

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

• electrode [60]. A distinct scheme of rectification compared to our picture has been proposed recently, which leads to a pure SC, that is, a flow of angular momentum without accompanying CC. This type of SC rectification may be generated by spin pumping techniques [61] or via the spin-Seebeck effect [62

Computing the T-matrix of a scattering object with multiple plane wave illuminations

• Martin Fruhnert,
• Ivan Fernandez-Corbaton,
• Vassilios Yannopapas and
• Carsten Rockstuhl

Beilstein J. Nanotechnol. 2017, 8, 614–626, doi:10.3762/bjnano.8.66

• arbitrary constant angle. The symmetry that is corresponding to this transformation invariance is duality. Helicity is defined as the product of the total angular momentum J and the direction of the linear momentum of the wave P/|P|[48] It has the two eigenvalues 1 and −1, and the corresponding eigenstates

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

• Rasmus Bjerregaard Christensen,
• Jing-Tao Lü,
• Per Hedegård and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2016, 7, 68–74, doi:10.3762/bjnano.7.8

• of current via (angular) momentum transfer [30]. Mode 1 is made up by two principal bare modes, while mode 2 does so in abstract mode space, and consists of mainly three bare modes. In both cases the nonconservative force pump energy into these modes when they oscillate around closed loops. We note

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• , they can be transformed into their complex, rotational invariant representations: where is the n = 3 metal orbital with angular momentum and magnetic quantum number m = ±1. To distinguish contributions from the pure phthalocyanine (Pc) ligand and the copper (Cu) center, we introduced and

• , respectively. Likewise, with cS ≈ 0.90, we can write for the SOMO: where is the n = 3 metal orbital with angular momentum and projection m = ± 2 onto the z-axis. Finally, the HOMO has no metal contributions and thus we have trivially . The representations introduced in Equation 4 have the advantage that the

Nonconservative current-driven dynamics: beyond the nanoscale

• Brian Cunningham,
• Tchavdar N. Todorov and
• Daniel Dundas

Beilstein J. Nanotechnol. 2015, 6, 2140–2147, doi:10.3762/bjnano.6.219

• we refer to as the waterwheel effect, differs from Joule heating [10][11] in two key respects. First, the growth in atomic kinetic energy is exponential. Second, it is not stochastic: the energy transferred in the waterwheel effect is stored in directional motion, specifically as generalised angular

• momentum [12]. In the early work above, it seemed that the waterwheel effect might require rather specialised conditions. The effect operates fundamentally through the coupling of pairs of normal modes to form generalised rotors driven by the current. This requires modes that are close in frequency and are

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

• Toma Susi,
• Thomas Pichler and
• Paola Ayala

Beilstein J. Nanotechnol. 2015, 6, 177–192, doi:10.3762/bjnano.6.17

• level, each core state is expected to split into two components due to spin–orbit coupling, corresponding to orbital angular momentum quantum numbers of j = 1/2 and 3/2. The magnitude of the spin–orbit splitting is thought to be rather insensitive to the chemical environment and predicted by theory to

Spin annihilations of and spin sifters for transverse electric and transverse magnetic waves in co- and counter-rotations

• Hyoung-In Lee and
• Jinsik Mok

Beilstein J. Nanotechnol. 2014, 5, 1887–1898, doi:10.3762/bjnano.5.199

• momentum; multiplexing; nanoparticle; orbital; Poynting; spin; trajectory; Introduction Electromagnetic (EM) waves are now fairly well understood at least in terms of angular momentum (AM) and Poynting vector (PV). For instance, the AM of spin-one photons is divisible into the spin and orbital parts [1][2

• associated trajectories. Section "Angular Momentum and Spins" considers the AM and photon spins, thus coming up with several extraordinary concepts. Section "Discussion" provides additional arguments, followed by "Conclusion" summarizing the principle behind spin sifters and other issues. Results Formulation

• exterior as can be inferred from Equation 13, see [23]. Angular momentum and spins With the superscript "tot" referring to "total", we define the vector of the total energy flow density (FD) or total linear momentum [3]: It turns out that is identical to the Poynting vector in the dielectric media in

k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy

• Martin Esmann,
• Simon F. Becker,
• Bernard B. da Cunha,
• Jens H. Brauer,
• Ralf Vogelgesang,
• Petra Groß and
• Christoph Lienau

Beilstein J. Nanotechnol. 2013, 4, 603–610, doi:10.3762/bjnano.4.67

• , corresponding to an angular momentum, which manifests itself in a field distribution of the form . The propagation of the wire modes is described by a transcendental equation, which can be derived from Maxwell’s equations and the appropriate boundary conditions at the metal–dielectric interface [13][14][15][16