Ferromagnetic phases of bcc and fcc Fe, Co, and Ni

Magnetoelectric coupling at metal surfaces

“…As it is known that the magnetic structure of Fe delicately depends on the volume of the crystallographic unit cell [14], also a large variety of magnetic orders is expected for Fe thin films. In the following, it will be shown that these properties make 2 ML films of Fe/Cu(111) a model system for MEC at metal surfaces.…”

“…An STM is an ideal tool with which to investigate this because it can image surface structures on the nanoscale and it provides high electric fields underneath the tip to induce phase transitions via MEC. As model system, we chose two atomic layers thick Fe islands grown on Cu(111): Fe is known to have a structural instability between face-centered cubic and body-centered cubic phases as well as a strong variation of the magnetic order following slight changes in the unit cell volume [14]. For this model system we have shown that nonvolatile magnetic information can be written on the nanometer scale by the application of high electric fields.…”

Theoretical investigation into the possibility of very large moments in Fe16N2

“…However, it is known that fcc Fe, while ordinarily nonmagnetic, enters a high spin state upon expansion of the cell volume. 43 Therefore, we have explored the energy landscape as a function of total (spin) cell moment and c a , allowing the former to range from 34 -48 µ B (corresponding to average spin moments of 2.12 -3.0 µ B per Fe) and the latter from 1.0 -1.5 (holding a fixed in one set of calculations and volume fixed in another). We only constrain the total spin moment of the cell and not the magnitude of the individual moments.…”

Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

“…According to a theoretical prediction, fcc Ni exists only in a ferromagnetic phase, while bcc Ni exhibits a transition from a ferromagnetic to a nonmagnetic phase, 14 when the Wigner-Seitz radius r WS decreases to a critical value of about 2.60 Å. The transition from a nonmagnetic to ferromagnetic state has been predicted for epitaxial bcc Ni films which are subject to a 1% lattice expansion caused by a substrate.…”

“…The transition from a nonmagnetic to ferromagnetic state has been predicted for epitaxial bcc Ni films which are subject to a 1% lattice expansion caused by a substrate. 14 The magnetic moments in Ni films exhibit a strong dependence on the number of monolayers, the substrate, and the structure of the covering ͑cap͒ layers. For example, the magnetic moment of bcc Ni film deposited on a Fe͑001͒ substrate is 0.86 B per atom for a one monolayer thick film, and 0.69 B for a two monolayer thick film.…”