Evidence for spin current driven Bose-Einstein condensation of magnons.

The quanta of magnetic excitations - magnons - are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now.

Optical Frequency Up-Conversion of the Ferromagnetic Resonance in an Ultrathin Garnet Mediated by Magnetoelastic Coupling.

We perform ultrafast pump-probe measurements on a nanometer-thick crystalline Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy. Tuning the photon energy of the pump laser pulses above and below the material's band gap, we trigger ultrafast optical and spin dynamics via both one- and two-photon absorption. Contrary to the common scenario, the optically induced excitation induces an increase up to 20% of the ferromagnetic resonance frequency of the material.

Ultrafast Amplification and Nonlinear Magnetoelastic Coupling of Coherent Magnon Modes in an Antiferromagnet.

We investigate the role of domain walls in the ultrafast magnon dynamics of an antiferromagnetic NiO single crystal in a pump-probe experiment with variable pump photon energy. Analyzing the amplitude of the energy-dependent photoinduced ultrafast spin dynamics, we detect a yet unreported coupling between the material's characteristic terahertz- and gigahertz-magnon modes. We explain this unexpected coupling between two orthogonal eigenstates of the corresponding Hamiltonian by modeling the magnetoelastic interaction between spins in different domains.

Ultra-low damping insulating magnetic thin films get perpendicular.

A magnetic material combining low losses and large perpendicular magnetic anisotropy (PMA) is still a missing brick in the magnonic and spintronic fields. We report here on the growth of ultrathin Bismuth doped YFeO (BiYIG) films on GdGaO (GGG) and substituted GGG (sGGG) (111) oriented substrates. A fine tuning of the PMA is obtained using both epitaxial strain and growth-induced anisotropies.