scholarly journals SPECTRUMS OF SUPERCONDUCTING STATES AND TRIPLET EFFECTS IN SUPERCONDUCTOR/FERROMAGNET MULTILAYERS

Doklady BGUIR ◽  
2019 ◽  
pp. 38-42
Author(s):  
V. N. Kushnir
Keyword(s):  
Layer Structure ◽  
Magnetic Moments ◽  
Complete Suppression ◽  
Central Layer ◽  
Critical Temperatures ◽  
Irregular Structures ◽  
Ferromagnetic Layers ◽  
Singlet Component ◽  
Channeling Effect ◽  
Superconducting Condensate

We report the results of studies of triplet superconductivity in structures with alternating superconductor and ferromagnet layers, as a part of the general problem of the properties of the spectra of superconductivity states depending on the magnetic state of the multilayer structure. Ferromagnetic layers are assumed monodomain and possessing inplane magnetic moments. In numerical examples, we used the parameters of the well-studied Nb/PdNi system. The critical temperatures and distributions of singlet and triplet currents depending on the relative orientation of the magnetic moments of the ferromagnetic layers are calculated in the formalism of the Usadel equations for 5- and 3-layer irregular structures. The following results are obtained. (1) The channeling effect of triplet pairs by a narrow central layer of a superconductor with complete suppression of the singlet component in it was confirmed. (2) The “0–1”-transition between the phases of a superconducting condensate of opposite symmetry induced by the transport current is predicted. (3) The effect of a double crossover of states on the dependence of the critical temperature, Tc, versus the angle θ between the magnetic moments of the ferromagnetic layers adjacent to the central layer of the superconductor in a 3-layer structure is predicted. The crossovers are reflected by a sharp turns in the Tc (θ) curve, while the infinitely small asymmetry of the structure eliminates the non-analyticity of this characteristic.

scholarly journals CHIRAL QUARK MODEL (χQM) AND THE NUCLEON SPIN

2004 ◽  
Vol 19 (29) ◽  
pp. 5027-5041 ◽  
Author(s):  
HARLEEN DAHIYA ◽  
MANMOHAN GUPTA
Keyword(s):  
Angular Momentum ◽  
Magnetic Moments ◽  
Distribution Functions ◽  
Gluon Polarization ◽  
Spin Distribution ◽  
Polarization Functions ◽  
Singlet Component ◽  
Configuration Mixing ◽  
The Right ◽  
E866 Data

Using χ QM with configuration mixing, the contribution of the gluon polarization to the flavor singlet component of the total spin has been calculated phenomenologically through the relation [Formula: see text] as defined in the Adler–Bardeen scheme, where ΔΣ on the right-hand side is Q2 independent. For evaluation the contribution of gluon polarization [Formula: see text], ΔΣ is found in the χ QM by fixing the latest E866 data pertaining to [Formula: see text] asymmetry and the spin polarization functions whereas ΔΣ(Q2) is taken to be 0.30±0.06 and αs=0.287±0.020, both at Q2=5 GeV 2. The contribution of gluon polarization Δg' comes out to be 0.33 which leads to an almost perfect fit for spin distribution functions in the χ QM . When its implications for magnetic moments are investigated, we find perfect fit for many of the magnetic moments. If an attempt is made to explain the angular momentum sum rule for proton by using the above value of Δg', one finds the contribution of gluon angular momentum to be as important as that of the [Formula: see text] pairs.

scholarly journals Control of the noncollinear interlayer exchange coupling

2020 ◽  
Vol 6 (48) ◽  
pp. eabd8861
Author(s):  
Zachary R. Nunn ◽  
Claas Abert ◽  
Dieter Suess ◽  
Erol Girt
Keyword(s):  
Exchange Coupling ◽  
Magnetic Moments ◽  
Interlayer Exchange Coupling ◽  
Magnetic Structures ◽  
Spintronic Devices ◽  
Spacer Layer ◽  
Ferromagnetic Layers ◽  
Almost All ◽  
Interlayer Exchange ◽  
Coupling Angle

Interlayer exchange coupling in transition metal multilayers has been intensively studied for more than three decades and is incorporated into almost all spintronic devices. With the current spacer layers, only collinear magnetic alignment can be reliably achieved; however, controlling the coupling angle has the potential to markedly expand the use of interlayer exchange coupling. Here, we show that the coupling angle between the magnetic moments of two ferromagnetic layers can be precisely controlled by inserting a specially designed magnetic metallic spacer layer between them. The coupling angle is controlled solely by the composition of the spacer layer. Moreover, the biquadratic coupling strength, responsible for noncollinear alignment, is larger than that of current materials. These properties allow for the fabrication and study of not yet realized magnetic structures that have the potential to improve existing spintronic devices.

Atomic Layer-by-Layer Engineering of High Tc Materials and Heterostructure Devices

MRS Bulletin ◽  
1994 ◽  
Vol 19 (9) ◽  
pp. 44-50 ◽  
Author(s):  
J.N. Eckstein ◽  
I. Bozovic ◽  
G.F. Virshup
Keyword(s):  
Magnetic Moments ◽  
High Mobility ◽  
Atomic Layer ◽  
Layer By Layer ◽  
Strongly Correlated ◽  
Critical Temperatures ◽  
Electron Phonon Coupling ◽  
Dielectric And Optical Properties ◽  
Polaronic Transport ◽  
Heterostructure Devices

Oxides exhibit most of the interesting phenomena known to occur in solid-state systems. As a class of materials they may be richer in phenomenology than any other comparable class. Oxides can be insulators, semiconductors, or metals. The copperoxide-based compounds we have studied are superconductors with the highest critical temperatures. In some oxides, electrons manifest simple single-particle transport properties, with a high mobility; in others, they show strongly correlated behavior resulting in a Mott-Hubbard transition, localization, and charge- or spin-density waves. In some oxides, electron-phonon coupling leads to polaronic transport. Others show collective states such as magnetism; in some there are large local magnetic moments that can couple to form ferromagnetic or antiferromagnetic phases that exist up to high temperatures. Yet others have large nonlinear dielectric and optical properties. In fact, it would seem there is very little that some such oxide couldn't do for or to the experimenter.

scholarly journals Controllable two- vs three-state magnetization switching in single-layer epitaxial Pd1-xFex films and epitaxial Pd0.92Fe0.08/Ag/Pd0.96Fe0.04 heterostructure

2021 ◽  
Author(s):  
Igor Yanilkin ◽  
Amir Gumarov ◽  
Gulnaz Gizzatullina ◽  
Roman Yusupov ◽  
Lenar Tagirov
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Applied Magnetic Field ◽  
Magnetization Reversal ◽  
Easy Axis ◽  
Magnetic State ◽  
Magnetic Moments ◽  
Single Layer ◽  
Wide Range ◽  
Ferromagnetic Layers

We have investigated the low-temperature magnetoresistive properties of a thin epitaxial Pd0.92Fe0.08 film at different directions of the current and the applied magnetic field. The obtained experimental results are well described within an assumption of a single-domain magnetic state of the film. In a wide range of the appled field directions, the magnetization reversal proceeds in two steps via the intermediate easy axis. An epitaxial heterostructure of two magnetically separated ferromagnetic layers, Pd0.92Fe0.08/Ag/Pd0.96Fe0.04, was synthesized and studied with the dc magnetometry. Its magnetic configuration diagram has been constructed and the conditions have been determined for a controllable switching between stable parallel, orthogonal, and antiparallel arrangements of magnetic moments of the layers.

LARGE EFFECTS OF MAGNETIC FIELD ON JOSEPHSON CURRENTS THROUGH ANTIFERROMAGNETIC BARRIERS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3316-3316
Author(s):  
L. P. GOR'KOV ◽  
V. Z. KRESIN
Keyword(s):  
Magnetic Field ◽  
Detrimental Effect ◽  
Magnetic Moments ◽  
Mixed Valence ◽  
Josephson Current ◽  
Current Amplitude ◽  
Weak Links ◽  
Ferromagnetic Domains ◽  
Ferromagnetic Layers ◽  
Mixed Valence Manganites

Ferromagnetism being known to have a detrimental effect on superconductivity, we consider the Josephson current amplitude for junctions built up of antiferromagnetic metallic weak links. It is assumed that the latter consist of ferromagnetic layers with magnetizations aligned alternatively along perpendicular-to-the-layers direction. Currents between two superconducting electrodes flow along the layers. Such antiferromagnetic structure realizes itself in mixed valence manganites (the so-called A-phase), in an array of parallel ferromagnetic domains, or even in artificial GMR heterostructures. It is shown that even minor canting of magnetic moments in the presence of magnetic fields causes remarkable oscillations in the value of the Josephson current amplitude.

CRITICAL TEMPERATURES OF THE ISING MODEL ON THE BETHE LATTICE FOR ARBITRARY VALUES OF SPIN

2012 ◽  
Vol 26 (01) ◽  
pp. 1250003 ◽  
Author(s):  
E. JURČIŠINOVÁ ◽  
M. JURČIŠIN
Keyword(s):  
Ising Model ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Bethe Lattice ◽  
Critical Temperatures ◽  
Spin Variable ◽  
Recursion Relations ◽  
Coordination Numbers ◽  
Full Structure ◽  
Very High

Using the method of recursion relations an exact solution of classical Ising models with arbitrary value of spin on the Bethe lattice with arbitrary coordination number is presented. Expressions for the spontaneous magnetization, for the magnetic moments of arbitrary orders, for the susceptibility, for the free energy, and for the specific heat are found as functions of quantities which are determined by the recursion relations. The behavior of the spontaneous magnetization for the Ising model on the Bethe lattice is investigated for systems with spin values up to s = 5 for various coordination numbers and the corresponding critical temperatures are determined. An approximate formula for determining the positions of the critical temperatures for arbitrary high values of the spin variable is found and discussed. It is shown that this formula allows one to determine the full structure of the critical temperatures with very high precision.

scholarly journals Magnetic properties of Tm2Fe16 under pressure

2018 ◽  
Vol 185 ◽  
pp. 04018
Author(s):  
Anatoly Kuchin ◽  
Zdenek Arnold ◽  
Jiri Kamarád ◽  
Sergey Platonov
Keyword(s):  
Magnetic Properties ◽  
High Temperature ◽  
Low Temperature ◽  
Magnetic Moments ◽  
External Pressure ◽  
Complete Suppression ◽  
Moderate Pressure ◽  
Volume Changes ◽  
Uniaxial Magnetic Anisotropy ◽  
Magnetic States

The magnetic properties of the non-stoichiometric Tm2Fe16 compound under hydrostatic pressures up to 1 GPa were studied. We have revealed that the high-temperature ferrimagnetic state easily magnetized in the basal plane is very sensitive to the volume changes and even moderate pressure is sufficient to its complete suppression and transformation to a helimagnetic state. At the same time, the low-temperature ferrimagnetic state easily magnetized along the hexagonal axis does not disappear under pressure and the temperature of its transition to the high-temperature magnetic states increases under pressure. The remarkable stability of the ground ferrimagnetic state under external pressure can be attributed to the strengthening of the uniaxial magnetic anisotropy and to the mutual perpendicular orientation of the magnetic moments in the ground and the high-temperature magnetic states.

Mossbauer studies in transition metal chemistry. II. Iron(III) methoxides and halomethoxides

1974 ◽  
Vol 27 (9) ◽  
pp. 1833 ◽  
Author(s):  
RL Martin ◽  
IAG Roos
Keyword(s):  
Transition Metal ◽  
High Spin ◽  
Layer Structure ◽  
Magnetic Moments ◽  
Three Dimensional ◽  
Transition Metal Chemistry ◽  
Mössbauer Studies ◽  
Metal Chemistry ◽  
Lattice Effects ◽  
High Spin Iron

M�ssbauer spectra are reported for a series of insoluble methoxide and halomethoxide complexes of tervalent iron which are known to exhibit pronounced antiferromagnetic interactions.1-3 The M�ssbauer study confirms that all the compounds contain high-spin iron(111) and that the reduced magnetic moments arise from antiferromagnetically coupled iron atoms within polymerized species. The quadrupole splittings which are due solely to lattice effects and anisotropic bonding are consistent with some of the previously proposed structures but definitely exclude others. It is concluded that the M�ssbauer data are better rationalized in terms of a three-dimensional layer structure in which the ratio of halogen to methoxide is progressively varied in a FeX3 lattice.

The Remagnetization Process Feature of Trilayer Nanodisks

2010 ◽  
Vol 168-169 ◽  
pp. 249-252
Author(s):  
A.V. Ognev ◽  
M.E. Stebliy ◽  
A.S. Samardak ◽  
A. Nogaret ◽  
L.A. Chebotkevich
Keyword(s):  
Kerr Effect ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Magnetic Moments ◽  
Force Microscopy ◽  
Vortex States ◽  
Reversal Process ◽  
Ferromagnetic Layers

The remagnetization process and the distribution of magnetic moments in arrays of trilayer nanodisks Co(10 nm)/Pd(0.8 nm)/Co(10 nm) with diameters D = 200 and 400 nm were studied by the magnetooptical Kerr effect (MOKE) and magnetic force microscopy (MFM). It is shown that in the nanodisks with D = 200 nm the magnetisation reversal process can be carried out by the vortex states or one-domain configurations with the antiparallel orientation of moments in the adjacent ferromagnetic layers. In arrays of nanodisks with D = 400 nm the vortex states are formed only.

scholarly journals Long range and highly tunable interaction between local spins coupled to a superconducting condensate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Felix Küster ◽  
Sascha Brinker ◽  
Samir Lounis ◽  
Stuart S. P. Parkin ◽  
Paolo Sessi
Keyword(s):  
Interatomic Distance ◽  
Rational Design ◽  
Magnetic Moments ◽  
Scanning Tunneling Spectroscopy ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Design Strategies ◽  
High Tunability ◽  
Atomic Manipulation ◽  
Superconducting Condensate

AbstractInterfacing magnetism with superconducting condensates is rapidly emerging as a viable route for the development of innovative quantum technologies. In this context, the development of rational design strategies to controllably tune the interaction between magnetic moments is crucial. Here we address this problem demonstrating the possibility of tuning the interaction between local spins coupled through a superconducting condensate with atomic scale precision. By using Cr atoms coupled to superconducting Nb, we use atomic manipulation techniques to precisely control the relative distance between local spins along distinct crystallographic directions while simultaneously sensing their coupling by scanning tunneling spectroscopy. Our results reveal the existence of highly anisotropic interactions, lasting up to very long distances, demonstrating the possibility of crossing a quantum phase transition by acting on the direction and interatomic distance between spins. The high tunability provides novel opportunities for the realization of topological superconductivity and the rational design of magneto-superconducting interfaces.

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