Spin-polarized quasiparticle control in a double spin-filter tunnel junction

Muduli, P. K.

doi:10.1103/physrevb.96.024514

Cited by 3 publications

(4 citation statements)

References 74 publications

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“…The coupling between itinerant carriers and collective magnetic order parameters implied in STT makes this quantity as the practical tool for the usage in magnetic random access memories and oscillator circuits [7][8][9][10][11][12]. In addition to extensive theoretical and experimental studies of the STT in ferromagnetic (F) spin-valve and domain structures, there have been studies devoted to the STT in structures with superconducting parts [13][14][15][16][17][18][19][20][21][22]. Actually, with novel and featuring applications, the ferromagnet superconductor heterostructures have been the active topics of the condensed-matter physics research [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Spin transfer torque and exchange coupling in Josephson junctions with ferromagnetic superconductor reservoirs

Shomali

Asgari

2019

J. Phys.: Condens. Matter

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In this paper, the spin transfer torque (STT) and the exchange coupling of the Josephson junctions containing the interesting cases of diffusive/ballistic-triplet/singlet ferromagnetic superconductor (FS) materials together with the diffusive Josephson junction of the form S1/F1/I1/N/I2/F2 with I being the insulating barrier are investigated. Using the Nazarov quantum circuit theory, it is found that for the diffusive FS1/N/FS2 structure the STT only appears in the normal direction to the plane of the exchange fields of the F1 and F2. This results in the antiparallel/parallel or vice versa parallel/antiparallel transition of the favorable exchange coupling depending on the considered parameters of the system, including the nonmagnetic spacer thickness, the superconducting phase difference, the length and the exchange field of the ferromagnets. Furthermore, the analyze of the width of the transitions, the phase difference interval in which an interlayer length-induced antiparallel/parallel transition can be occurred, is performed. For instance, as the exchange field or the temperature increases, the interval of phase difference gets larger. On the other hand, the ballistic Josephson junction containing the triplet ferromagnetic superconductor reservoirs solving the 16×16 Bogoliubov-de-Gennes equation is studied. It is found that although the exchange fields of the FS are laid in the z and y direction, the STT interestingly exists in all three directions of x, y and z. This exciting finding suggests that the favorable equilibrium configuration concerning the least exchange coupling occurs in the relative exchange field direction different from 0 or π. To the best of our knowledge it is for the first time that the occurrence of the in-plane STT is reported. Moreover, the occurrence of the beat like behavior with two oscillation period for the out-of-plane STT is interestingly acquired.

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Section: Introductionmentioning

confidence: 99%

Spin transfer torque and exchange coupling in Josephson junctions with ferromagnetic superconductor reservoirs

Shomali

Asgari

2019

J. Phys.: Condens. Matter

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“…The equivalent internal field of the Zeeman splitting in Al-EuS systems has been reported to be as large as 5 T [43]. Another S-FI combination explored so far is GdN-NbN [44,45]. This system shows, however, a weaker and less clear spin splitting than the Al-europium chalcogenide combination, due to the influence of the sizable spin-orbit interaction in Nb compared to the Al-based devices.…”

Section: Ferromagnetic Insulator-superconductor Structuresmentioning

confidence: 99%

“…Here we assume that the dominant heat relaxation mechanism on the reservoir R with volume Ω N is due to electron-phonon interaction with strength Σ N , described by Eq. (45). In addition, we assume that the spin accumulation on the island, produced by the nonequilibrium driving, is negligibly small due to eV =" spin relaxation.…”

Section: Heat Current Beyond Linear Responsementioning

confidence: 99%

Thermal, electric and spin transport in superconductor/ferromagnetic-insulator structures

Heikkilä

Силаев

Virtanen

et al. 2019

Progress in Surface Science

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A ferromagnetic insulator (FI) attached to a conventional superconductor (S) changes drastically the properties of the latter. Specifically, the exchange field at the FI/S interface leads to a splitting of the superconducting density of states. If S is a superconducting film, thinner than the superconducting coherence length, the modification of the density of states occurs over the whole sample. The coexistence of the exchange splitting and superconducting correlations in S/FI structures leads to striking transport phenomena that are of interest for applications in thermoelectricity, superconducting spintronics and radiation sensors. Here we review the most recent progress in understanding the transport properties of FI/S structures by presenting a complete theoretical framework based on the quasiclassical kinetic equations. We discuss the coupling between the electronic degrees of freedom, charge, spin and energy, under non-equilibrium conditions and its manifestation in thermoelectricity and spin-dependent transport.

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confidence: 99%

Study of Niobium Mononitride Thin Films Grown Using High Power Impulse Magnetron Sputtering

Kalal

Kumar

Karmakar

et al. 2021

Physica Rapid Research Ltrs

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Niobium mononitride (NbN) has gained considerable attention because of its superconducting and refectory properties making it a promising material in devices like spin filters, Josephson junctions, superconducting qubits, and transistors especially when combined with other semiconductors and/or magnetic materials. [1][2][3][4][5][6][7] The ease of formation along with a relatively higher superconducting transition temperature (T C > 10 K) and a lower superconducting energy gap (Δ(0) % 3 meV) has made NbN to be one of the most studied superconducting materials for a wide range of applications. [8] Additionally, it has been widely used as an oxidation, wear-resistant layer, and diffusion barrier in protective and hard coatings. [9,10] NbN thin films can be synthesized using different growth techniques such as chemical vapor deposition, [11] ion beam-assisted deposition, [12] reactive direct current magnetron sputtering (dcMS), molecular beam epitaxy, [1] atomic layer deposition, [13] pulsed laser deposition, [14] etc.Among these, the dcMS has been widely used to grow thin films due to its cost effectiveness and the ability to grow uniform thin films. In a typical dcMS process, the plasma is mostly dominated by neutrals and the fraction of ionized species is very small (typically less than 5%). [15] The structural properties of the sputtered films strongly depend on the kinetic energies and ionization state of the impinging atomic and molecular species on the surface of growing films. It is well-known that the low ionization in dcMS process results into a porous and loosely packed microstructure and forms a large density of defects in the grown films. [16,17] To overcome these issues high power impulse magnetron sputtering (HiPIMS) has been developed. [18,19] In the HiPIMS technique, high power pulses are applied to a sputtering target contrary to a constant DC voltage in the dcMS. The use of high power pulses onto the sputtering target results in a large fraction of ionized-sputtered species. In addition, gases that are present in the vicinity of target also get ionized. [20] Earlier experimental and theoretical reports suggest that high ion to neutral ratios during HiPIMS process results into better thin-films' qualities in terms of denser microstructure, smoother surface, and interfaces. [21][22][23] Recent experimental and theoretical results [24,25] suggest that Nb vacancies are the most dominant

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Spin-polarized quasiparticle control in a double spin-filter tunnel junction

Cited by 3 publications

References 74 publications

Spin transfer torque and exchange coupling in Josephson junctions with ferromagnetic superconductor reservoirs

Spin transfer torque and exchange coupling in Josephson junctions with ferromagnetic superconductor reservoirs

Thermal, electric and spin transport in superconductor/ferromagnetic-insulator structures

Study of Niobium Mononitride Thin Films Grown Using High Power Impulse Magnetron Sputtering

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