Electronic states ofRFe2O4(R=Lu,Yb,Tm

Abstract

We here report an investigation of the electronic states in the RFe 2 O 4 (R = Lu, Yb, Tm, Y) mixed-valence ferrites by means of soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements together with ab initio theoretical calculations. The presence of Fe +2 and Fe +3 pure ionic species is discarded in the XAS spectra at the O K edge in both experimental data and simulations based on the multiple scattering theory. Similarly, no trace of Fe +2 /Fe +3 contributions is detected in the XMCD spectra at the Fe K edge. On the other hand, the XAS and XMCD spectra at the Fe L 2,3 edges can be well described in terms of Fe +2 /Fe +3 contributions, and are also supported by multiplet calculations. This finding can be interpreted as the existence of a mixture of 3d 5 /3d 6 configurations at the Fe atoms. Alternative ferrimagnetic spin orderings based on a trimodal Fe valence distribution are also proposed and discussed. Finally, a possible explanation for the strong dependence of the Fe L 2,3 edges XMCD signal magnitude on both the sample surface preparation and detection method is presented.

Unraveling the structure and bonding evolution of the newly discovered iron oxide FeO2

“…These findings support the picture that FeO 2 is a peroxide, in agreement with the initial interpretation of Hu et al [4]. The oxidation state for Fe in FeO 2 is likely to attain a partial charge state Fe +(2+δ) , where δ ranges from 0 to 1 [52]. Further details on the charge states in FeO 2 and several other transition-metal oxides are given in Table S3 [46].…”

Reactive spark plasma-assisted synthesis of metastable rare-earth ferrites with widely tunable charge ordering transfer properties

“…This indicates that the Re Fe 2 O 4 as produced by RSPS herein in general exhibits a higher proportion associated with the Fe 3+ configuration, as compared to previously reported values as synthesized in a reducing atmosphere. This is consistent with the smaller magnitude in the Mott temperature T 0 and activation energy E A as observed in the sample produced herein, compared to reported values, 33 as previously shown in Fig. 4f.…”

“…It is also worth noting that the ratio of L-3 L /L-3 R as observed in Re Fe 2 O 4 produced herein is smaller compared to reported values 33 ( e.g. , as one representative case demonstrated in Fig.…”

“…The Fe: L-3 edge splits into two peaks: the left peak (L-3 L ) is associated with the Fe 2+ orbital configuration, while the right peak (L-3 R ) represents Fe 3+ . 33,34 In Fig. 5(c), the ratio in the above two peaks (L-3 L /L-3 R ) is plotted as a function of the rare-earth ionic radius for the NEXAFS spectra measured at room temperature and 250 K. The L-3 L /L-3 R shows a reducing tendency with an increasing r Re , while the elevation in temperature also reduces L-3 L /L-3 R .…”

Dynamics of Surface Spins in Small Core–Shell Magnets of Li0.35Zn0.30Fe2.35O4 Bonds over a Carbon Surface and Tailored Magnetic Properties

“…[1][2][3][4][5][6][7][8][9][10][11] Charge ordering causes multiferroics in rare-earth (R) series RFe 2 O 4 , particularly for R = Lu of all paired 4f 14 spins. [12][13][14][15] As the magnetic and electric orderings concur simultaneously lead to couple multifunctional features in new types of devices. Oxygen polygons lock spins (cations) in a specific network of it unites the spins, charges, orbital degrees of freedom and lattice one another to function together as a single system.…”