Heusler-based synthetic antiferrimagnets.

Antiferromagnet spintronic devices eliminate or mitigate long-range dipolar fields, thereby promising ultrafast operation. For spin transport electronics, one of the most successful strategies is the creation of metallic synthetic antiferromagnets, which, to date, have largely been formed from transition metals and their alloys. Here, we show that synthetic antiferrimagnetic sandwiches can be formed using exchange coupling spacer layers composed of atomically ordered RuAl layers and ultrathin, perpendicularly magnetized, tetragonal ferrimagnetic Heusler layers.

Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy.

Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers.

Quasiparticle self-consistent GW method: a short summary.

We have developed a quasiparticle self-consistent GW method (QSGW), which is a new self-consistent method to calculate the electronic structure within the GW approximation. The method is formulated based on the idea of a self-consistent perturbation; the non-interacting Green function G(0), which is the starting point for GWA to obtain G, is determined self-consistently so as to minimize the perturbative correction generated by GWA. After self-consistency is attained, we have G(0), W (the screened Coulomb interaction) and G self-consistently.

All-electron self-consistent GW approximation: application to Si, MnO, and NiO.

We present a new kind of self-consistent GW approximation based on the all-electron, full-potential linear muffin-tin orbital method. By iterating the eigenfunctions of the GW Hamiltonian, self-consistency in both the charge density and the quasiparticle spectrum is achieved. We explain why this form of self-consistency should be preferred to the conventional one.

Coherent control of femtosecond energy localization in nanosystems.

We predict and quantitatively evaluate the unique possibility of concentrating the energy of an ultrafast excitation of a nanosystem in a small part of the whole system by means of coherent control (phase modulation of the exciting ultrashort pulse). Such concentration is due to dynamic properties of surface plasmons and leads to local fields enhanced by orders of magnitude. This effect exists for both "engineered" and random nanosystems.