Noncollinear spin structure in Fe3+xCo3−xT

Abstract

Neutron powder diffraction has been used to investigate the spin structure of the hard-magnetic alloy Fe 3+x Co 3−x Ti 2 (x = 0, 2, 3). The materials are produced by rapid quenching from the melt, they possess a hexagonal crystal structure, and they are nanocrystalline with crystallite sizes D of the order of 40 nm. Projections of the magnetic moment onto both the crystalline c axis and the basal plane were observed. The corresponding misalignment angle exhibits a nonlinear decrease with x, which we explain as a micromagnetic effect caused by Fe-Co site disorder. The underlying physics is a special kind of random-anisotropy magnetism that leads to the prediction of 1/D 1/4 power-law dependence of the misalignment angle on the crystallite size.

Topological phase transitions and Berry-phase hysteresis in exchange-coupled nanomagnets

“…The magnetization reversal starts randomly making domains at a field of 0.06 T and these domains expand as the field is increased and finally coalescence of the domain occurs at a high field. Note that not only do we have topological contributions due to magnetic domains, but we also have a topological contribution to THE due to chiral spin inhomogeneity, and imaging of those spins is difficult [47,60].…”

Synergistic computational and experimental discovery of novel magnetic materials

“…A combination of AGA search, DFT calculations, and experiment has led to the discovery of a set of Fe-and Co-rich compounds Fe 3+x Co 3-x Ti 2 ( 0 ≤ x  3), which form a hexagonal structure with a P-6m2 symmetry. [72][73][74][75] The basic Fe 3 Co 3 Ti 2 structure is schematically shown in Fig. 9A and exhibits a significant Fe/Co anti-site mixing or disorder.…”

“…73 The best fit indicated a significant Fe/Co antisite A high magnetic anisotropy (13.0 Mergs/cm 3 ) and saturation magnetic polarization (11.4 kG) were measured at 10 K for the Fe 6 Ti 2 compound, 73 and a further NPD analysis shows that Fe substitution for Co in Fe 3+x Co 3-x Ti 2 decreases Fe/Co occupancy disorder and improves the magnetic properties including the uniaxial character of the magnetic anisotropy. 75 The projection of the magnetic moments with respect to the crystalline c axis at 100 K is shown as a function of x in Fig. 10A.…”