Empty square as a hard-layer for MRAM

In this paper, we propose a new design , which utilizes "empty squares" or narrow squares or narrow rings as the basic element for the fabrication of hard layer of MRAM. At remanence a stable bi-domain state called the "onion" state is observed. The onion state corresponds to each half of the square ring, on either side of the diagonal, having the same magnetization orientation and forming head-to-head and tail-to-tail domain walls.