Wirtualne seminarium ACMiN: Shedding a new “light” onto the puzzles of magnetite

Akademickie Centrum Materiałów i Nanotechnologii AGH zaprasza na wirtualne seminarium, które odbędzie się 15 października 2020 r. o godz. 14.00.

Referat pt. Shedding a new “light” onto the puzzles of magnetite wygłosi dr Hebatalla Elnaggar z Uniwersytetu w Utrechtcie.


Magnetite (Fe3O4) is one of the most abundant Fe bearing minerals on Earth and it finds many applications in areas such as paleomagnetism, medicine, data recording, and engineering [1]. It is believed to have governed the early Martian climate and favoured biologically relevant chemical reactions [2]. Fe3O4 is known to man as the first compass [3] and an intriguing half metallic oxide of interest to spintronics applications [4]. It also undergoes a metal to insulator transition at TV ∼125K which is referred to as the Verwey transition [5, 6, 7]. Ever since the work of Verwey, Fe3O4 was considered as an archetype of strongly correlated oxide systems. This gave rise to considerable efforts devoted to understanding the origin of the Verwey transition. It has however remained a daunting task to determine the driving force of the transition due to its complexity: Fe3O4 is a mixed valence, strongly correlated system where many interactions such as Jahn-Teller (dynamical and static), spin-orbit and phonons are very close in energetics. In this talk, I will discuss a series of Resonant Inelastic X-ray Scattering (RIXS) measurements that shed new light on some of the open questions. I will focus on: (a) Investigation of local correlations in the high temperature phase of Fe3O4 using RIXS in the soft and hard X-ray regime [8]. (b) Investigation of non-collinear ordering of the orbital magnetic moments in the high temperature phase of Fe3O4 using a combination of X-ray linear and circular magnetic dichroism measurements in the hard X-ray regime [9].

[1] D. W. Dunlop and Ö. Özdemir. Rock Magnetism. Cambridge University Press, 1997.
[2] N. J. Tosca, et. al., Nat. Geoscience, 11(9):635–639, 2018.
[3] W. Lowrie. Fundamentals of Geophysics. Cambridge University Press, 2 edition, 2007.
[4] J. P. Hong, et. a., Appl. Phys. Lett., 83(8):1590–1592, 2003.
[5] E. J. W. Verwey, Nature, 144(3642):327–328, 1939.
[6] E. J. W. Verwey and P. W. Haayman, Physica, 8(9):979 – 987, 1941.
[7] E. J. W. Verwey and E. L. Heilmann, J. Chem. Phys., 15(4):174–180, 1947.
[8] H. Elnaggar et. al., Phys. Rev. Lett., 123, 207201, 2019.
[9] H. Elnaggar et. al., Phys. Rev. B., 101, 085107, 2020.

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