B. F. Miao

Electrical Detection of Direct and Alternating Spin Current Injected from a Ferromagnetic Insulator into a Ferromagnetic Metal

We report room temperature electrical detection of spin injection from a ferromagnetic insulator (YIG) into a ferromagnetic metal (Permalloy, Py). Non-equilibrium spins with both static and precessional spin polarizations are dynamically generated by the ferromagnetic resonance of YIG magnetization, and electrically detected by Py as dc and ac spin currents, respectively. The dc spin current is electrically detected via the inverse spin Hall effect of Py, while the ac spin current is converted to a dc voltage via the spin rectification effect of Py which is resonantly enhanced by dynamic exchange interaction between the ac spin current and the Py magnetization. Our results reveal a new path for developing insulator spintronics, which is distinct from the prevalent but controversial approach of using Pt as the spin current detector.

Micromagnetic study of excitation modes of an artificial skyrmion crystal

We present a micromagnetic study on the eigen excitations of an artificial skyrmion crystal, which has been experimentally confirmed to be stable at room temperature without the need of any Dzyaloshinsky-Moriya interaction (DMI). Three in-plane rotational modes and one breathing-type mode are identified. We find the intrinsic origin of the dynamics of skyrmion crystal is the nontrivial magnetic texture instead of DMI. And the rotational direction of a skyrmion is solely determined by the sign of the skyrmion number, irrespective of its circulation sense, evidencing the topological nature of the magnetic skyrmion.

Spectroscopy of self-assembled one-dimensional atomic string: The role of step edge

Step-edge guided Gd one-dimensional atomic strings on Ag(111) surface are studied by scanning tunneling microscopy and spectroscopy at low temperature. Spectroscopy measurements show a characteristic peak, 65u2009meV above Fermi level in sharp contrast with tight-binding calculations of a string on a flat terrace. Good agreement can be obtained when the step edges are included in the calculations, revealing their roles on the electronic spectra of the self-assembled strings guided by step edges. The results are further confirmed by the spectroscopy study of Fe strings on a flat terrace and near step edges constructed by atomic manipulation.