Risto Ojajärvi
YOU?
Author Swipe
View article: Pairing at a single Van Hove point
Pairing at a single Van Hove point Open
We show that an interacting electronic system with a single ordinary or extended Van Hove point, which crosses the Fermi energy, is unstable against triplet superconductivity. The pairing mechanism is unconventional. There is no Cooper ins…
View article: Superconductivity due to fluctuating loop currents
Superconductivity due to fluctuating loop currents Open
Orbital magnetism and the loop currents (LCs) that accompany it have been proposed to emerge in many systems, including cuprates, iridates, and kagome superconductors. In the case of cuprates, LCs have been put forward as the driving force…
View article: Reducing the frequency of the Higgs mode in a helical superconductor coupled to an LC circuit
Reducing the frequency of the Higgs mode in a helical superconductor coupled to an LC circuit Open
Supplementary material includes derivations of all the susceptibilities, the frequency dependence of χAΔ, the explanation of vanishing of χAΔ in the diffusive limit and the derivations of the equations of motion.
View article: Superconductivity due to fluctuating loop currents
Superconductivity due to fluctuating loop currents Open
Orbital magnetism and the loop currents (LC) that accompany it have been proposed to emerge in many systems, including cuprates, iridates, and kagome superconductors. In the case of cuprates, LCs have been put forward as the driving force …
View article: Reducing the frequency of the Higgs mode in a helical superconductor coupled to an LC-circuit
Reducing the frequency of the Higgs mode in a helical superconductor coupled to an LC-circuit Open
We show that the amplitude, or Higgs mode of a superconductor with strong spin-orbit coupling and an exchange field, couples linearly to the electromagnetic field. Furthermore, by coupling such a superconductor to an LC resonator, we demon…
View article: Coupling the Higgs mode and ferromagnetic resonance in spin-split superconductors with Rashba spin-orbit coupling
Coupling the Higgs mode and ferromagnetic resonance in spin-split superconductors with Rashba spin-orbit coupling Open
Supplementary material includes the details of the symmetry operators and the calculation of the susceptibilities.
View article: Coupling the Higgs mode and ferromagnetic resonance in spin-split superconductors with Rashba spin-orbit coupling
Coupling the Higgs mode and ferromagnetic resonance in spin-split superconductors with Rashba spin-orbit coupling Open
We consider the Higgs mode at nonzero momentum in superconductors and demonstrate that in the presence of Rashba spin-orbit coupling, it couples linearly with an external exchange field. The Higgs-spin coupling dramatically modifies the sp…
View article: Giant enhancement to spin battery effect in superconductor/ferromagnetic insulator systems
Giant enhancement to spin battery effect in superconductor/ferromagnetic insulator systems Open
We develop a theory of the spin battery effect in superconductor/ferromagnetic insulator (SC/FI) systems taking into account the magnetic proximity effect. We demonstrate that the spin-energy mixing enabled by the superconductivity leads t…
View article: Spin and charge currents driven by the Higgs mode in high-field superconductors
Spin and charge currents driven by the Higgs mode in high-field superconductors Open
Higgs mode in superconducting materials describes slowly-decaying oscillations of the order parameter amplitude. We demonstrate that in magnetic superconductors with built-in spin-splitting field Higgs mode is strongly coupled to the spin …
View article: Nonlinear spin torque, pumping, and cooling in superconductor/ferromagnet systems
Nonlinear spin torque, pumping, and cooling in superconductor/ferromagnet systems Open
We study the effects of the coupling between magnetization dynamics and the\nelectronic degrees of freedom in a heterostructure of a metallic nanomagnet\nwith dynamic magnetization coupled with a superconductor containing a steady\nspin-sp…
View article: Non-linear spin torque, pumping and cooling in superconductor/ferromagnet systems
Non-linear spin torque, pumping and cooling in superconductor/ferromagnet systems Open
We study the effects of the coupling between magnetization dynamics and the electronic degrees of freedom in a heterostructure of a metallic nanomagnet with dynamic magnetization coupled with a superconductor containing a steady spin-split…
View article: Mean-field theory for superconductivity in twisted bilayer graphene
Mean-field theory for superconductivity in twisted bilayer graphene Open
Recent experiments show how a bilayer graphene twisted around a certain magic\nangle becomes superconducting as it is doped into a region with approximate\nflat bands. We investigate the mean-field $s$-wave superconducting state in\nsuch a…
View article: Clauser-Horne-Shimony-Holt Bell inequality test in an optomechanical device
Clauser-Horne-Shimony-Holt Bell inequality test in an optomechanical device Open
We propose here a scheme based on the measurement of quadrature phase coherence that is aimed at testing the Clauser-Horne-Shimony-Holt Bell inequality in an optomechanical setting. Our setup is constituted by two optical cavities dispersi…
View article: Competition of electron-phonon mediated superconductivity and Stoner magnetism on a flat band
Competition of electron-phonon mediated superconductivity and Stoner magnetism on a flat band Open
The effective attractive interaction between electrons, mediated by electron-phonon coupling, is a well-established mechanism of conventional superconductivity. In metals exhibiting a Fermi surface, the critical temperature of superconduct…
View article: Electron-phonon interaction in flat-band superconductivity
Electron-phonon interaction in flat-band superconductivity Open
Parhaiten tunnettu suprajohtavuuden syntymekanismi perustuu fononien välittämään vetovoimaan elektronien välillä. Tässä tutkielmassa tutkin fononien välittämää suprajohtavuutta systeemeissä, jossa elektronivyöt ovat tasomaisia. Tasovyöllä …