scholarly journals Multiorbital singlet pairing and d + d superconductivity

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Emilian M. Nica ◽  
Qimiao Si
Keyword(s):  
Time Reversal ◽  
Heavy Fermion ◽  
Degrees Of Freedom ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Matrix Structure ◽  
Spin Singlet ◽  
Low Energies ◽  
Triplet Pairing ◽  
Orbital Space

AbstractRecent experiments in multiband Fe-based and heavy-fermion superconductors have challenged the long-held dichotomy between simple s- and d-wave spin-singlet pairing states. Here, we advance several time-reversal-invariant irreducible pairings that go beyond the standard singlet functions through a matrix structure in the band/orbital space, and elucidate their naturalness in multiband systems. We consider the sτ3 multiorbital superconducting state for Fe-chalcogenide superconductors. This state, corresponding to a d + d intra- and inter-band pairing, is shown to contrast with the more familiar d + id state in a way analogous to how the B- triplet pairing phase of 3He superfluid differs from its A- phase counterpart. In addition, we construct an analog of the sτ3 pairing for the heavy-fermion superconductor CeCu2Si2, using degrees-of-freedom that incorporate spin-orbit coupling. Our results lead to the proposition that d-wave superconductors in correlated multiband systems will generically have a fully-gapped Fermi surface when they are examined at sufficiently low energies.

scholarly journals Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Woo Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny H. Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Degrees Of Freedom ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Research Activities ◽  
Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

scholarly journals Spin-orbit coupling in the kagome lattice with flux and time-reversal symmetry

2021 ◽  
Vol 103 (19) ◽  
Author(s):  
Irakli Titvinidze ◽  
Julian Legendre ◽  
Maarten Grothus ◽  
Bernhard Irsigler ◽  
Karyn Le Hur ◽  
...  
Keyword(s):  
Time Reversal ◽  
Orbit Coupling ◽  
Time Reversal Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Kagome Lattice ◽  
Kagomé Lattice

Spin Hall Effect Induced by Sound

2012 ◽  
Vol 190 ◽  
pp. 117-120
Author(s):  
I.I. Lyapilin
Keyword(s):  
Degrees Of Freedom ◽  
Spin Current ◽  
Coherent Motion ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Spin Coherence ◽  
Nanoscale Systems ◽  
The Subject ◽  
Normal Current ◽  
Low Dimensional

Transport of electronic spins in low-dimensional and nanoscale systems is the subject of thenovel and quickly developing eld of spintronics. The possibility of coherent spin manipulationrepresents an ultimate goal of this eld. Typically, spin transport is strongly aected by couplingof spin and orbital degrees of freedom. The inuence of the spin orbit interaction is twofold.The momentum relaxation due to the scattering of carriers, inevitably leads to spin relaxationand destroys the spin coherence. On the other hand, the controlled orbital motion of carrierscan result in a coherent motion of their spins. Thus, the spin orbit coupling is envisaged as apossible tool for spin controling in electronic devices. In particular, it is possible to generatespin polarization and spin currents by applying electric eld, the phenomenon known as thespin-Hall eect (SHE) [1- 3]. The eect is manifested in the form of a spin current directedperpendicular to the normal current, which takes place in an electric eld.

Space-group operations and time-reversal for a Dirac electron in a crystal field

1958 ◽  
Vol 243 (1235) ◽  
pp. 546-554 ◽  
Keyword(s):  
Dirac Equation ◽  
Crystal Field ◽  
Time Reversal ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Theory ◽  
Space Group ◽  
Basic Formalism ◽  
Dirac Electron

It is shown in the first part how the basic formalism of the theory of spin-orbit coupling in the band theory of crystals can be deduced at once from the Dirac equation without the usual ambiguities over improper rotations associated with the formalism based on the Pauli-Schrödinger equation. In the second part it is shown that the original proofs of the time-reversal theorems given by Wigner are unnecessarily complicated.

scholarly journals Emergent Chiral Symmetry: Parity and Time Reversal Doubles

1997 ◽  
Vol 12 (29) ◽  
pp. 5325-5357 ◽  
Author(s):  
A. P. Balachandran ◽  
S. Vaidya
Keyword(s):  
Time Reversal ◽  
Particle Physics ◽  
Nuclear Physics ◽  
Degrees Of Freedom ◽  
High Energy ◽  
Approximate Symmetry ◽  
Opposite Parity ◽  
Doublet Structure ◽  
Low Energies ◽  
Oppenheimer Approximation

There are numerous examples of approximately degenerate states of opposite parity in molecular physics. Theory indicates that these doubles can occur in molecules that are reflection-asymmetric. Such parity doubles occur in nuclear physics as well, among nuclei with odd A ~ 219–229. We have also suggested elsewhere that such doubles occur in particle physics for baryons made up of cbu and cbd quarks. In this article, we discuss the theoretical foundations of these doubles in detail, demonstrating their emergence as a surprisingly subtle consequence of the Born–Oppenheimer approximation, and emphasizing their bundle-theoretic and topological underpinnings. Starting with certain "low energy" effective theories in which classical symmetries like parity and time reversal are anomalously broken on quantization, we show how these symmetries can be restored by judicious inclusion of "high-energy" degrees of freedom. This mechanism of restoring the symmetry naturally leads to the aforementioned doublet structure. A novel byproduct of this mechanism is the emergence of an approximate symmetry (corresponding to the approximate degeneracy of the doubles) at low energies which is not evident in the full Hamiltonian. We also discuss the implications of this mechanism for Skyrmion physics, monopoles, anomalies and quantum gravity.

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