Pressure tuning of charge ordering in iron oxide. Issue 1 (December 2018)

• Record Type: Journal Article
• Authors: Ovsyannikov, Sergey; Bykov, Maxim; Bykova, Elena; Glazyrin, Konstantin; Manna, Rudra; Tsirlin, Alexander; Cerantola, Valerio; Kupenko, Ilya; Kurnosov, Alexander; Kantor, Innokenty; Pakhomova, Anna; Chuvashova, Irina; Chumakov, Aleksandr; Rüffer, Rudolf; McCammon, Catherine; Dubrovinsky, Leonid
• Is Part Of: Nature communications. Volume 9:Issue 1(2018)
• Page Start: 1
• Page End: 11
• Publication Date: 2018-12
• Subjects: Biology -- Periodicals; Physical sciences -- Periodicals; 505
• DOI: 10.1038/s41467-018-06457-x
• Languages: English
• ISSNs: 2041-1723

Abstract

Abstract A Verwey-type charge-ordering transition in magnetite at 120 K leads to the formation of linear units of three iron ions with one shared electron, called trimerons. The recently-discovered iron pentoxide (Fe4 O5 ) comprising mixed-valent iron cations at octahedral chains, demonstrates another unusual charge-ordering transition at 150 K involving competing formation of iron trimerons and dimerons. Here, we experimentally show that applied pressure can tune the charge-ordering pattern in Fe4 O5 and strongly affect the ordering temperature. We report two charge-ordered phases, the first of which may comprise both dimeron and trimeron units, whereas, the second exhibits an overall dimerization involving both the octahedral and trigonal-prismatic chains of iron in the crystal structure. We link the dramatic change in the charge-ordering pattern in the second phase to redistribution of electrons between the octahedral and prismatic iron chains, and propose that the average oxidation state of the iron cations can pre-determine a charge-ordering pattern. The charge order transition of commonly known magnetite has only recently been unraveled. Here, the measurement of the low-temperature high-pressure phase diagram of a related material (Fe4 O5 ) elucidates the interplay of average oxidation state and charge-ordering phenomena in the iron oxide family.