Long Range Charge Ordering in Magnetite Below the Verwey Transition

Wright, J.P.; Attfield, J. Paul; Radaelli, P. G.

doi:10.1103/physrevlett.87.266401

Cited by 322 publications

(386 citation statements)

References 27 publications

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“…A decrease in T V for decreasing Fe 3 O 4 thicknesses is observed, which has been previously reported by other authors, 7,19,33 and explained as a slight nonstoichiometry of the films 33,34 or strain due to the epitaxial growth on the substrate. 7 Recently, it has been suggested 8,19 that in ultrathin films where the APBs domain size is small, the long-range order of the Fe 2+ and Fe 3+ ions at the octahedral sites, necessary for the Verwey transition to occur, can be inhibited, 35 producing a decrease in T V . Indeed, this decrease in the Verwey transition temperature as a function of Fe 3 O 4 film thickness ͑t͒ can be fitted to the phenomenological expression given by Eq.…”

Section: Resultsmentioning

confidence: 99%

Origin of the giant magnetic moment in epitaxialFe3O4thin films

et al. 2010

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We study the enhanced magnetic moment observed in epitaxial magnetite ͑Fe 3 O 4 ͒ ultrathin films ͑t Ͻ 15 nm͒ grown on MgO ͑001͒ substrates by means of pulsed laser deposition. The Fe 3 O 4 ͑001͒ thin films exhibit high crystallinity, low roughness, and sharp interfaces with the substrate, and the existence of the Verwey transition at thicknesses down to 4 nm. The evolution of the Verwey transition temperature with film thickness shows a dependence with the antiphase boundaries density. Superconducting quantum interference device ͑SQUID͒ and vibrating sample magnetometry measurements in ultrathin films show a magnetic moment much higher than the bulk magnetite value. In order to study the origin of this anomalous magnetic moment, polarized neutron reflectivity ͑PNR͒, and x-ray magnetic circular dichroism ͑XMCD͒ experiments have been performed, indicating a decrease in the magnetization with decreasing sample thickness. X-ray photoemission spectroscopy measurements show no metallic Fe clusters present in the magnetite thin films. Through inductively coupled plasma mass spectroscopy and SQUID magnetometry measurements performed in commercial MgO ͑001͒ substrates, the presence of Fe impurities embedded within the substrates has been observed. Once the substrate contribution has been corrected, a decrease in the magnetic moment of magnetite thin films with decreasing thickness is found, in good agreement with the PNR and XMCD measurements. Our experiments suggest that the origin of the enhanced magnetic moment is not intrinsic to magnetite but due to the presence of Fe impurities in the MgO substrates.

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Section: Resultsmentioning

confidence: 99%

Origin of the giant magnetic moment in epitaxialFe3O4thin films

et al. 2010

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“…On the other hand, a charge modulation can be induced by electronic Peierls instability, the so called charge density wave (CDW) 4,5 . As electron states are localized as in the Mott states, it appears as a charge order-type modulation due to intersite Coulomb interactions [6][7][8] . In a system with heavy elements, the large SOC can stabilize the localized spin-orbit Mott state as observed in iridates 9 , and then the charge-ordered Mott state naturally leads a novel electronic framework of the interplay.…”

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confidence: 99%

Charge-ordering cascade with spin–orbit Mott dimer states in metallic iridium ditelluride

Lee

Kim

et al. 2015

Nat Commun

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Spin-orbit coupling results in technologically-crucial phenomena underlying magnetic devices like magnetic memories and energy-efficient motors. In heavy element materials, the strength of spin-orbit coupling becomes large to affect the overall electronic nature and induces novel states such as topological insulators and spin-orbit-integrated Mott states. Here we report an unprecedented charge-ordering cascade in IrTe 2 without the loss of metallicity, which involves localized spin-orbit Mott states with diamagnetic Ir 4 þ -Ir 4 þ dimers. The cascade in cooling, uncompensated in heating, consists of first order-type consecutive transitions from a pure Ir 3 þ phase to Ir 3 þ -Ir 4 þ charge-ordered phases, which originate from Ir 5d to Te 5p charge transfer involving anionic polymeric bond breaking. Considering that the system exhibits superconductivity with suppression of the charge order by doping, analogously to cuprates, these results provide a new electronic paradigm of localized charge-ordered states interacting with itinerant electrons through large spin-orbit coupling.

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“…1͑a͒ and 2͑a͒, altogether leading to ͱ 12a p ϫ ͱ 12a p ϫ 3c p . This exceptionally large threedimensional superlattice has never been documented in x = 0.71, and the corresponding volume ͑36 times of the primitive cell͒ is far more significant than what is usually observed for a superlattice such as a few times larger in x = 0.5, 8,16 Fe 3 O 4 , 24 and AgNiO 2 . 25 Using ͱ 12a p ϫ ͱ 12a p ϫ 3c p , the careful indexing of all diffraction spots in Fig.…”

Section: Resultsmentioning

confidence: 95%

X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering inγ-NaxCoO2(x=

et al. 2009

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We have recently demonstrated that x = 0.71 and 0.84 are the two most stable single-phase compounds above x = 0.5 in ␥-Na x CoO 2 ͓G. J. Shu et al., Phys. Rev. B 76, 184115 ͑2007͒; F. C. Chou et al., Phys. Rev. Lett. 101, 127404 ͑2008͔͒, and this structural investigation was performed on the single crystals and pulverized samples elaborately synthesized therein. Using the complementary techniques of x-ray and electron diffractions, we unambiguously established the existence of superlattices in x = 0.71 and 0.84, ͱ 12a p ϫ ͱ 12a p ϫ 3c p , and ͱ 13a p ϫ ͱ 13a p ϫ 3c p ͑a p and c p , the hexagonal primitive cell parameters͒, respectively. The exceptionally large superlattice for x = 0.71 arises from the long-range three-dimensional sodium ordering, consisting of the spirallike sodium-trimer chain screwing along c axis and being decorated with alternating truncated-triangle and honeycomb sodium sublattices in ab plane. The trimers in the neighboring sodium planes show corner-sharedlike characteristics along the chain direction. A larger interplane separation of the trimers that was expected to minimize the trimer interlayer Coulomb repulsion was, however, not observed, and all Co ions in the superlattice show similar charge characteristics. In x = 0.84, the large superlattice is rather a result of the long-range ordering of sodium monomers both in ab plane and along c axis. The differences in the superlattice structure and the corresponding long-range sodium ordering between x = 0.71 and 0.84 may provide the critical information in understanding their distinctly different physical properties from structural aspects.

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Long Range Charge Ordering in Magnetite Below the Verwey Transition

Cited by 322 publications

References 27 publications

Origin of the giant magnetic moment in epitaxialFe3O4thin films

Origin of the giant magnetic moment in epitaxialFe3O4thin films

Charge-ordering cascade with spin–orbit Mott dimer states in metallic iridium ditelluride

X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering inγ-NaxCoO2(x=

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