Mayergoyz, Serpico, and Bertotti Publish in Physical Review B

A paper co-authored by ECE Alford L. Ward Professor Isaak Mayergoyz, Giorgio Bertotti, Claudio Serpico, titled, “Conservative-like effects in spin-transfer-driven magnetization dynamics” was accepted as a regular article in Physical Review B on September 17.

The publication’s abstract is as follows:

It is shown that under certain conditions spin transfer results in conservative-like magnetization dynamics. This dynamics occurs along closed precessional-type trajectories, and it admits a special integral of motion which is reduced to the usual magnetic energy when the spin current is reduced to zero. The existence of this conservative-like dynamics is due to the symmetry properties of the magnetization dynamics equation with respect to simultaneous inversions of magnetization and time. When an external dc magnetic field is applied parallel to the spin polarization, the conservative-like magnetization dynamics is transformed into relaxations. It is demonstrated that there exists such a state function (Lyapunov function) that monotonically either increases or decreases during these relaxations, depending on the directions of the injected current and applied dc magnetic field. These results hold in the absences of intrinsic (thermal) damping. When the intrinsic damping is included in the description, mutual compensation between field-induced and damping-induced non-conservative effects may occur, which may eventually lead to the appearance of limit cycles, that is, of magnetization self-oscillations.

Physical Review B is the largest and most comprehensive international journal specializing in condensed matter and materials physics, publishing important papers on a wide range of topics. The journal has an impact factor of 3.767 (2012) and is ranked number one in total citations in condensed matter physics.

Mayergoyz, Bertotti, and Serpico have been collaborating on research in magnetics for some time. Serpico, a former post-doc of Mayergoyz, is now a Professor of Electrical Engineering at the University of Naples, “Frederico II.” He has also served as an Editor of IEEE Transactions on Magnetics in the areas of electromagnetism, computational magnetics, and electromagnetic devices. Bertotti is a physicist and researcher in the electromagnetism division of L’Instituto Nazionale de Ricerca Metrologica (INRIM) in Torino, Italy. Mayergoyz teaches and leads a research group within the Department of Electrical and Computer Engineering at the University of Maryland, College Park.

Published September 18, 2014