Roger Ward

Abstract:

A large-scale striped array of width 3.4 μm has been fabricated in 400-nm-thick epitaxial (1 1 0) DyFe2 films with Laves phase structure using a UV direct write system. The magnetic and magneto-optical properties of the sample were characterized by a vibrating sample magnetometer and magneto-optical Kerr magnetometry, respectively. The close easy-axis [-1 1 0] direction, confirmed by VSM, was chosen for patterning. The MO Kerr loops reveal that an additional anisotropy can be induced by the shape of the stripes, which can obviously enhance the coercivity of the close easy-axis [-1 1 0] loop. The magnitude of this additional anisotropy was determined to be 4.2 × 10⁵ erg/cm³, which is not sufficient to change the coercivity of the hard-axis loop due to a large intrinsic anisotropy along the hard-axis [0 0 1] direction. © 2006 Elsevier B.V. All rights reserved.

Abstract:

Transmission electron microscopy (TEM) is employed to characterize ex situ the interface between the bottom Fe (001) electrode and MgO (001) barrier in a magnetic tunnel junction (MTJ) deposited by molecular beam epitaxy. High resolution TEM images are compared with multislice-based simulations of oxidized and sharp interfaces to conclude that at least the part of the interface is not oxidized. In addition, the, spacing between the Fe and O layers at the interface is measured and found to be comparable with theoretical calculations in the literature of sharp interfaces. This result offers a methodology to characterize the interface structure of MTJs, which is important to determine the magneto-transport properties of the device.