Search results for "magneettiset ominaisuudet"
showing 7 items of 37 documents
Magnetoelectric effects in superconductor/ferromagnet bilayers
2018
We demonstrate that the hybrid structures consisting of a superconducting layer with an adjacent spin-textured ferromagnet demonstrate the variety of equilibrium magnetoelectric effects originating from coupling between the conduction electron spin and superconducting current. By deriving and solving the generalized Usadel equation which takes into account the spin-filtering effect we find that a supercurrent generates spin polarization in the superconducting film which is non-coplanar with the local ferromagnetic moment. The inverse magnetoelectric effect in such structures is shown to result in the spontaneous phase difference across the magnetic topological defects such as a domain wall …
Electron-induced massive dynamics of magnetic domain walls
2020
We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire, focusing on inertial effects on the DW due to interaction with a conduction electron bath. We develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived microscopically, including the full response kernel which is nonlocal in time. The DW dynamics is described by two collective degrees of freedom: position and tilt angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). Th…
Giant enhancement to spin battery effect in superconductor/ferromagnetic insulator systems
2021
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 to the enhancement of spin accumulation by several orders of magnitude relative to the normal state. This finding can explain the recently observed giant inverse spin Hall effect generated by thermal magnons in the SC/FI system. We suggest a nonlocal electrical detection scheme which can directly probe the spin accumulation driven by the magnetization dynamics. We predict a giant Seebeck effect converting the magnon temperature bias into the nonlocal voltag…
Triplet-State Position and Crystal-Field Tuning in Opto‐Magnetic Lanthanide Complexes : Two Sides of the Same Coin
2019
Lanthanide complex‐based luminescence thermometry and single‐molecule magnetism are two effervescent research fields, owing to the great promise they hold from an application standpoint. The high thermal sensitivity achievable, their contactless nature, along with sub‐micrometric spatial resolution make these luminescent thermometers appealing for accurate temperature probing in miniaturized electronics. To that end, single‐molecule magnets (SMMs) are expected to revolutionize the field of spintronics, thanks to the improvements made in terms of their working temperature – now surpassing that of liquid nitrogen – and manipulation of their spin state. Hence, the combination of such opto‐magn…
Visualization of Moiré Magnons in Monolayer Ferromagnet
2023
| openaire: EC/H2020/788185/EU//E-DESIGN Two-dimensional magnetic materials provide an ideal platform to explore collective many-body excitations associated with spin fluctuations. In particular, it should be feasible to explore, manipulate, and ultimately design magnonic excitations in two-dimensional van der Waals magnets in a controllable way. Here we demonstrate the emergence of moiré magnon excitations, stemming from the interplay of spin-excitations in monolayer CrBr3 and the moiré pattern arising from the lattice mismatch with the underlying substrate. The existence of moiré magnons is further confirmed via inelastic quasiparticle interference, showing the appearance of a dispersion …
The Role of Orbital Symmetries in Enforcing Ferromagnetic Ground State in Mixed Radical Dimers
2018
One of the first steps in designing ferromagnetic (FM) molecular materials of p-block radicals is the suppression of covalent radical–radical interactions that stabilize a diamagnetic ground state. In this contribution, we demonstrate that FM coupling between p-block radicals can be achieved by constructing mixed dimers from different radicals with differing symmetries of their singly occupied molecular orbitals. The applicability of this approach is demonstrated by studying magnetic interactions in organic radical dimers built from different derivatives of the well-known phenalenyl radical. The calculated enthalpies of dimerization for different homo- and heterodimers show that the formati…
Theoretical and computational studies of magnetic anisotropy and exchange coupling in molecular systems
2018
The field of molecular magnetism studies the magnetic properties of molecular systems as opposed to conventional metal-based magnets. The high chemical modifiability of the constituting molecules makes such materials highly versatile, and the small size of the building blocks leads to the rise of various quantum mechanical phenomena, such as tunneling and entanglement. These phenomena can then be further utilized in the construction of nanoscale quantum devices. This dissertation describes computational and theoretical studies in the field of molecular magnetism using state-of-the-art quantum chemical methods based on ab initio multireference approaches and broken symmetry density functional t…