Details

Autor(en) / Beteiligte

• Matos, M.
• Terra, J.
• Ellis, D.E.
• Pimentel, A.S.

Titel

First principles calculation of magnetic order in a low-temperature phase of the iron ludwigite

Ist Teil von

• Journal of magnetism and magnetic materials, 2015-01, Vol.374, p.148-152

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The magnetic order of a low-temperature dimerized phase of Fe3O2BO3 is investigated through a density functional approach which considers full non-collinear spin–spin interactions, focusing on the 15K crystalline structure. It is found that Fe spins in the (Fe–Fe)5+ dimer, formed during the room temperature structural change of Fe3O2BO3, are parallel and have little freedom to rotate under interaction with neighbor Fe atoms. While the Fe dimer behaves as a heavy single magnetic unit the spin magnetic moment of the third Fe3+ atom of the Fe triad has, on the contrary, much more freedom to rotate. This is responsible for a canted spin ordering, revealed by a rotation of ~80° of the trivalent Fe spin relative to the spin orientation of the dimer, due to spin–spin interaction with divalent Fe atoms outside the triad. Canting is thus seen to be responsible for the very low net magnetization, experimentally observed in this compound (T<40K). •DFT non-collinear spin calculations are performed in a low-T phase of Fe3O2BO3.•Results show that the main Fe triad is formed by two distinct magnetic components.•The Fe dimer component shows surprisingly strong magnetic exchange energy.•Spin canting of the single-Fe component explains the system´s low magnetization.•Results provide quantitative support for local magnetism at high temperatures.