scholarly journals Unconventional supercurrent phase in Ising superconductor Josephson junction with atomically thin magnetic insulator

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
H. Idzuchi ◽  
F. Pientka ◽  
K.-F. Huang ◽  
K. Harada ◽  
Ö. Gül ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Orbit Coupling ◽  
Cooper Pairs ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Magnetic Domains ◽  
Magnetic Exchange ◽  
Spin Texture ◽  
Magnetic Insulator ◽  
Opening Up

AbstractIn two-dimensional (2D) NbSe2 crystal, which lacks inversion symmetry, strong spin-orbit coupling aligns the spins of Cooper pairs to the orbital valleys, forming Ising Cooper pairs (ICPs). The unusual spin texture of ICPs can be further modulated by introducing magnetic exchange. Here, we report unconventional supercurrent phase in van der Waals heterostructure Josephson junctions (JJs) that couples NbSe2 ICPs across an atomically thin magnetic insulator (MI) Cr2Ge2Te6. By constructing a superconducting quantum interference device (SQUID), we measure the phase of the transferred Cooper pairs in the MI JJ. We demonstrate a doubly degenerate nontrivial JJ phase (ϕ), formed by momentum-conserving tunneling of ICPs across magnetic domains in the barrier. The doubly degenerate ground states in MI JJs provide a two-level quantum system that can be utilized as a new dissipationless component for superconducting quantum devices. Our work boosts the study of various superconducting states with spin-orbit coupling, opening up an avenue to designing new superconducting phase-controlled quantum electronic devices.

scholarly journals Spin-orbit coupling suppression and singlet-state blocking of spin-triplet Cooper pairs

2021 ◽  
Vol 7 (3) ◽  
pp. eabe0128
Author(s):  
Sachio Komori ◽  
James M. Devine-Stoneman ◽  
Kohei Ohnishi ◽  
Guang Yang ◽  
Zhanna Devizorova ◽  
...  
Keyword(s):  
Orbit Coupling ◽  
Cooper Pairs ◽  
Triplet States ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
S Wave ◽  
Magnetic Exchange ◽  
Spin Singlet ◽  
Order Of Magnitude ◽  
Spin Triplet

An inhomogeneous magnetic exchange field at a superconductor/ferromagnet interface converts spin-singlet Cooper pairs to a spin-polarized triplet state. Although the decay envelope of triplet pairs within ferromagnetic materials is well studied, little is known about their decay in nonmagnetic metals and superconductors and, in particular, in the presence of spin-orbit coupling (SOC). Here, we investigate devices in which singlet and triplet supercurrents propagate into the s-wave superconductor Nb. In the normal state of Nb, triplet supercurrents decay over a distance of 5 nm, which is an order of magnitude smaller than the decay of spin-singlet pairs due to the SOC. In the superconducting state of Nb, triplet supercurrents are not able to couple with the singlet wave function and are thus blocked by the absence of available equilibrium states in the singlet gap. The results offer insight into the dynamics between s-wave singlet and s-wave triplet states.

scholarly journals Observation of quantum interference conductance fluctuations in metal rings with strong spin–orbit coupling

2020 ◽  
Vol 117 (24) ◽  
pp. 242402
Author(s):  
R. Ramos ◽  
T. Makiuchi ◽  
T. Kikkawa ◽  
S. Daimon ◽  
K. Oyanagi ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Metal Rings ◽  
Conductance Fluctuations ◽  
Strong Spin

scholarly journals Optical spin–orbit coupling in the presence of magnetization: photonic skyrmion interaction with magnetic domains

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xinrui Lei ◽  
Luping Du ◽  
Xiaocong Yuan ◽  
Anatoly V. Zayats
Keyword(s):  
Electromagnetic Waves ◽  
Magnetic Domain ◽  
Light Polarization ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Magnetic Domains ◽  
Spin Distribution ◽  
Magnetic Skyrmions ◽  
Almost All

Abstract Polarization and related spin properties are important characteristics of electromagnetic waves and their manipulation is crucial in almost all photonic applications. Magnetic materials are often used for controlling light polarization through the magneto-optical Kerr or Faraday effects. Recently, complex topological structures of the optical spin have been demonstrated in the evanescent light field, which in the presence of the spin–orbit coupling may form photonic skyrmions. Here, we investigate the optical spin–orbit coupling in the presence of magnetization and the interaction between photonic skyrmions and magnetic domains. We demonstrate that the magnetization is responsible for the modulation of the optical spin distribution, resulting in twisted Neel-type skyrmions. This effect can be used for the visualization of magnetic domain structure with both in plane and polar orientation of magnetization, and in turn for creation of complex optical spin distributions using magnetization patterns. The demonstrated interplay between photonic skyrmions and magneto-optical effects may also provide novel opportunities for investigation and manipulation of magnetic skyrmions using optical spin–orbit coupling.

scholarly journals Low-field Magnetic Anisotropy of Sr2IrO4

2022 ◽  
Author(s):  
Muhammad Nauman ◽  
Tayyaba Hussain ◽  
Joonyoung Choi ◽  
Nara Lee ◽  
Young Jai Choi ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Interaction ◽  
Exchange Interactions ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Easy Magnetization ◽  
Magnetic Exchange ◽  
Crystal Field Effect ◽  
Out Of Plane

Abstract Magnetic anisotropy in strontium iridate (Sr2IrO4) is essential because of its strong spin–orbit coupling and crystal field effect. In this paper, we present a detailed mapping of the out-of-plane (OOP) magnetic anisotropy in Sr2IrO4 for different sample orientations using torque magnetometry measurements in the low-magnetic-field region before the isospins are completely ordered. Dominant in-plane anisotropy was identified at low fields, confirming the b axis as an easy magnetization axis. Based on the fitting analysis of the strong uniaxial magnetic anisotropy, we observed that the main anisotropic effect arises from a spin–orbit-coupled magnetic exchange interaction affecting the OOP interaction. The effect of interlayer exchange interaction results in additional anisotropic terms owing to the tilting of the isospins. The results are relevant for understanding OOP magnetic anisotropy and provide a new way to analyze the effects of spin–orbit-coupling and interlayer magnetic exchange interactions. This study provides insight into the understanding of bulk magnetic, magnetotransport, and spintronic behavior on Sr2IrO4 for future studies.

scholarly journals Gate controlled anomalous phase shift in Al/InAs Josephson junctions

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
William Mayer ◽  
Matthieu C. Dartiailh ◽  
Joseph Yuan ◽  
Kaushini S. Wickramasinghe ◽  
Enrico Rossi ◽  
...  
Keyword(s):  
Phase Shift ◽  
Josephson Junction ◽  
Phase Difference ◽  
Josephson Junctions ◽  
Quantum Interference ◽  
Josephson Effect ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Superconducting Quantum Interference Device

AbstractIn a standard Josephson junction the current is zero when the phase difference between superconducting leads is zero. This condition is protected by parity and time-reversal symmetries. However, the combined presence of spin–orbit coupling and magnetic field breaks these symmetries and can lead to a finite supercurrent even when the phase difference is zero. This is the so called anomalous Josephson effect—the hallmark effect of superconducting spintronics—which can be characterized by the corresponding anomalous phase shift. Here we report the observation of a tunable anomalous Josephson effect in InAs/Al Josephson junctions measured via a superconducting quantum interference device. By gate controlling the density of InAs, we are able to tune the spin–orbit coupling in the Josephson junction. This gives us the ability to tune the anomalous phase, and opens new opportunities for superconducting spintronics, and new possibilities for realizing and characterizing topological superconductivity.

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