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

• ferromagnetic metal. The existence of such phenomena enables the creation of so-called Josephson π junctions with a negative critical current [1][2]. Oscillations of the pair wave function in the F layer leads to several interesting phenomena in S/F/(S) systems, including nonmonotonic critical temperature

• dependence [8][9][10][11][12], Josephson critical current oscillations [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], and density of states (DOS) oscillations [42][43][44][45]. S/F hybrid structures have many promising applications in

• situation is resolved by addition of an insulating barrier (I) yielding a SFIFS layer sequence, which allows one to realize much larger values of the product IcRn, where Ic is the critical current of the junction and Rn its normal state resistance [36][37][38]. Recently, SIFS junctions attracted much

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

• lead to a significant enhancement of the critical current through the junction. To control the magnetic alignment we propose to use a periodic system whose unit cell is a pseudo spin valve of structure F1/s/F2/s where F1 and F2 are two magnetic layers having different coercive fields. In order to check

• ]. These ideas can be implemented through a Josephson contact with two stable states: a high value of the critical current, IC, corresponds to the ”open” state and a low value to the ”closed” state. Such a device can be assembled if the weak link is a composite F/N/F trilayer (N is a normal metal) whose

• 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

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

• lowering the spin torque critical current switching density [22][23]. For various other applications a fast relaxation is favored, e.g., in magnetoresistive heads [24][25]. The FM/AF exchange coupling is one of the approaches to tune the magnetization relaxation by enhancing the field linewidth ΔH and

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

• transitions corresponds to a change of the fermion parity, and to the presence of zero-energy modes and discontinuities in the current–phase relation at zero temperature. These fermion parity transitions therefore can be revealed by the current discontinuities or by a measure of the critical current at low

• without a finite spin–orbit coupling. The resulting topological transitions coincide with a change of the fermion parity (topological invariant) and can be identified by discontinuities in the CPR and by a measure of the critical current at low temperatures. Results and Discussion Effective model We

• , since the energy shift U/2 of the Andreev levels do not depend on the phase φ. Critical current The topological transition can be probed also by a measure of the critical current of the junction. The critical current is defined as the maximum current of the junction up to the phase Ic = max Iφ. In the

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

• spinful TS nanowire model can generate a Josephson effect. The critical current is much smaller in the topological regime and exhibits a kink-like dependence on the Zeeman field along the wire. When a correlated quantum dot (QD) in the magnetic regime is present in the junction region, however, the

• signatures for the topological transition via the so-called φ0-behavior and/or through the kink-like dependence of the critical current on a Zeeman field driving the transition. We consider two different geometries in various regimes, e.g., the cotunneling regime where a controlled perturbation theory is

• field, which drives the TS wire across the topological phase transition, we find that the critical current exhibits a kink-like feature that is mainly caused by a suppression of the Andreev state contribution in the topological phase. (iii) Yet another possibility is offered by junctions containing a

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

• superconductor–isolator–superconductor (SIS) sandwich structure. One of the most important parameters of a Josephson junction is its critical current, Ic. This is the maximum superconducting current capable of flowing through the junction. A Josephson junction can be switched from the superconducting to the

• ≈ 2× 10−19 J, assuming a typical Ic ≈ 0.1 mA. The typical critical current value depends on the working (liquid helium) temperature, T = 4.2 K. For a proper operation of circuits it should be about three orders higher than the effective noise current value, IT = (2π/Φ0)kBT ≈ 0.18 μA, where kB is the

• determined by the dimensions of a Josephson junction. The area of a Josephson junction is closely related to its critical current density, jc. This parameter is one of the most important in the standard Nb-based tunnel junction fabrication process. It is fixed by materials properties of the insulating

Anodization-based process for the fabrication of all niobium nitride Josephson junction structures

• Massimiliano Lucci,
• Ivano Ottaviani,
• Matteo Cirillo,
• Fabio De Matteis,
• Roberto Francini,
• Vittorio Merlo and
• Ivan Davoli

Beilstein J. Nanotechnol. 2017, 8, 539–546, doi:10.3762/bjnano.8.58

• standard techniques [14]. The parameters of this junction are a representative result of our fabrication recipe: Josephson critical current density jc = 14.2 A/cm2, product of maximum critical current and normal resistance Ic·RNN = 1.63 mV, RNN/RSG = 10, Vm = IC·RSG = 16.3 mV, gap sum voltage VG = 3.6 mV

Thickness-modulated tungsten–carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields

• Ismael García Serrano,
• Javier Sesé,
• Isabel Guillamón,
• Hermann Suderow,
• Sebastián Vieira,
• Manuel Ricardo Ibarra and
• José María De Teresa

Beilstein J. Nanotechnol. 2016, 7, 1698–1708, doi:10.3762/bjnano.7.162

• by local maxima in the critical current, as shown in Figure 7. The measurement of the critical current as a function of the magnetic field has been carried out for the sample with pitch 100 nm at 1.9 K in order to verify that a minimum in the resistance corresponds to a maximum in the critical

• is steadily increased from zero up to the point in which the threshold voltage is reached, which corresponds to the critical current. As can be observed in Figure 7, there is good agreement between the existence of maxima in the critical current and the existence of minima in the resistance–field

• displayed for modes A (red) and B (blue). Comparison of the critical current density and the resistance versus magnetic field of the sample with pitch 100 nm at 1.9 K. The matching field corresponding to mode A, n = 4 is not observed in the resistance measurement at 1.9 K due to the low value of the

Adiabatic superconducting cells for ultra-low-power artificial neural networks

• Andrey E. Schegolev,
• Nikolay V. Klenov,
• Igor I. Soloviev and
• Maxim V. Tereshonok

Beilstein J. Nanotechnol. 2016, 7, 1397–1403, doi:10.3762/bjnano.7.130

• current flowing (Iout) in a superconducting loop of inductance, Lq. Hereafter, we use the normalization of inductance, lq = 2πIcLq/Φ0 (where Φ0 is the magnetic flux quantum, Ic is the junction’s critical current), magnetic flux, φX = 2πΦX/Φ0, and current, iout = Iout /Ic. The phase balance for the

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO₂, TiO₂ and Bi₂O₃ nanoparticles

• Tomasz Tański,
• Wiktor Matysiak and
• Barbara Hajduk

Beilstein J. Nanotechnol. 2016, 7, 1141–1155, doi:10.3762/bjnano.7.106

• conical shape (Taylor cone, Figure 1), accompanied by a movement of charges towards the grounded collector. The flow of the spinning liquid towards the collector is started when the critical current value is exceeded. It is stretched into a thin fibre under the field force. When the stream is reduced in

Physics, chemistry and biology of functional nanostructures II

• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2014, 5, 1218–1219, doi:10.3762/bjnano.5.134

• introduction of those in various materials allowed for solutions to problems which have been present for a long time. An example is the problematical increase of the critical current in new MgB2 superconducting material. This superconductor is very promising for technical applications due to its high critical

• current of up to 107 A/cm2. However, this critical current is only present in the MgB2 superconducting material when there is no magnetic field. The external magnetic field very rapidly suppresses the critical current and destroys the superconductivity of magnesium diboride. This issue was successfully

Enhancement of the critical current density in FeO-coated MgB₂ thin films at high magnetic fields

• Andrei E. Surdu,
• Hussein H. Hamdeh,
• Imad A. Al-Omari,
• David J. Sellmyer,
• Alexei V. Socrovisciuc,
• Andrei A. Prepelita,
• Ezgi T. Koparan,
• Ekrem Yanmaz,
• Valery V. Ryazanov,
• Horst Hahn and
• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2011, 2, 809–813, doi:10.3762/bjnano.2.89

• depositing FeO nanoparticles with a diameter of 10 nm onto the surface of MgB2 thin films on the critical current density was studied in comparison with the case of uncoated MgB2 thin films. We calculated the superconducting critical current densities (Jc) from the magnetization hysteresis (M–H) curves for

• both sets of samples and found that the Jc value of FeO-coated films is higher at all fields and temperatures than the Jc value for uncoated films, and that it decreases to ~105 A/cm2 at B = 1 T and T = 20 K and remains approximately constant at higher fields up to 7 T. Keywords: critical current

• material, with a hexagonal crystal structure and a critical temperature of Tc = 39 K, raised a lot of questions about its transport properties. This strong type-II superconductor has a fairly high critical current density in zero magnetic field, i.e., up to Jc ~ 1.6 × 107 A/cm2 at 15 K [2]. This