Magnetic phase diagram for the mixed-valence Eu oxide 
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Akahoshi, Daisuke; Koshikawa, Shuto; Nagase, Takuro; Wada, Eiji; Nishina, Kosuke; Kajihara, Ryo; Kuwahara, H.; Saito, Toshiaki

doi:10.1103/physrevb.96.184419

Cited by 18 publications

(5 citation statements)

References 27 publications

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“…Notably, T C of EuVO 2 H is higher than that of other Eu 2+ -based compounds with the perovskite structure (Table S2). ,− The relatively high T C of EuVO 2 H is ascribed to a short nearest-neighbor Eu–Eu distance (i.e., c -axis) compared to these perovskites, as seen in EuO under high pressure . A key factor facilitating the reduction of the Eu–Eu distance in EuVO 2 H is the flexible size of hydride anions: the substitution of EuO with EuH through the reaction with CaH 2 reduces the out-of-plane spacing, thereby avoiding underbonding of Eu 2+ .…”

Section: Resultsmentioning

confidence: 99%

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Namba,

Takatsu,

Mikita

et al. 2023

J. Am. Chem. Soc.

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Perovskite oxides ABO3 continue to be a major focus in materials science. Of particular interest is the interplay between A and B cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion and metal–insulator transition. However, the ICT properties were achieved and optimized by cationic substitution or ordering. Here we demonstrate an anionic approach to induce ICT using an oxyhydride perovskite, EuVO2H, which has alternating layers of EuH and VO2. A bulk EuVO2H behaves as a ferromagnetic insulator with a relatively high transition temperature (T C) of 10 K. However, the application of external pressure to the EuIIVIIIO2H bulk or compressive strain from the substrate in the thin films induces ICT from the EuIIH layer to the VIIIO2 layer due to the extended empty V d xy orbital. The ICT phenomenon causes the VO2 layer to become conductive, leading to an increase in T C that is dependent on the number of carriers in the d xy orbitals (up to a factor of 4 for 10 nm thin films). In addition, a large perpendicular magnetic anisotropy appears with the ICT for the films of <100 nm, which is unprecedented in materials with orbital-free Eu2+, opening new perspectives for applications. The present results provide opportunities for the acquisition of novel functions by alternating transition metal/rare earth layers with heteroanions.

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Section: Resultsmentioning

confidence: 99%

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Namba,

Takatsu,

Mikita

et al. 2023

J. Am. Chem. Soc.

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“…While some authors attributed it to the presence of Eu 2+ impurities [78], others excluded this +2 oxidation state. Indeed, by combining magnetic susceptibility measurements with 151 Eu Mössbauer spectroscopy, no Eu 2+ signal could be detected [92,[97][98][99] while its contribution is usually easily detected [80,100,101].…”

Section: The Low-temperature Upturnmentioning

confidence: 99%

Local structure and magnetism of LaxEu1−xPO4
Martel¹,
Rakhmatullin²,
Baldoví³
et al. 2019
Phys. Rev. B
6
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By combining high spinning speed (60 kHz) and low-field (4.7 T) 31 P solid-state NMR with magnetic susceptibility measurements, we experimentally characterized a series of solid solutions belonging to the La x Eu 1−x PO 4 (0 x 1) series. Analyses of the magnetic susceptibility data were carried out using the free ion model and crystal field theory calculations allowing to extract the electronic structure. The paramagnetic shifts of the P sites having one Eu 3+ cation in their surrounding were predicted by combining the determined crystal field and energy level values with density functional theory (DFT) calculations. For the La 0.9 Eu 0.1 PO 4 sample, these theoretical shifts gave a very good overall trend allowing the unambiguous attribution of each P site. This study paves the way for the future analysis of both magnetic susceptibility and NMR data for a broad range of materials containing paramagnetic rare-earth cations.

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“…The magnetic properties based on the EuH layer also significantly change as a result of ICT. EuVO 2 H exhibits ferromagnetism associated with Eu 2+ (4f 7 ; J = 7 / 2 ) with a Curie temperature ( T C ) of ∼10 K, surpassing those of other ferromagnetic Eu 2+ -based perovskites. − The introduction of ICT induces a 4-fold increase in T C , accompanied by a pronounced perpendicular magnetic anisotropy (PMA) comparable to that observed in the widely used permanent magnet Nd 2 Fe 14 B . Despite the unclear origin of this phenomenon, PMA in EuVO 2 H is distinct from that of conventional magnetic compounds due to the absence of orbital angular momentum in Eu 2+ ( L = 0).…”

Section: Introductionmentioning

confidence: 97%

Intersite Charge Transfer through Eu 4f Band Engineering in Eu_1–xSr_xVO₂H Oxyhydride Films

Namba,

Takatsu,

Murayama

et al. 2024

Chem. Mater.

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Perovskite oxyhydride EuVO 2 H exhibits a Mott insulating state derived from V III O 2 layers and a ferromagnetic state derived from Eu II H layers, with compressive strain inducing intersite charge transfer (ICT) in thin films, accompanied by an increased ferromagnetic transition temperature (T C ) and the emergence of perpendicular magnetic anisotropy (PMA). While ICT has previously been adjusted by film thickness (or substrate strain), this study demonstrates its control by Eu-site substitution with Sr. Utilizing topochemical hydride reduction, we fabricated Eu 1−x Sr x VO 2 H solid solution thin films on SrTiO 3 substrates, providing −0.6% compressive strain. With an increasing Sr content, the Eu valence remains almost unchanged, indicating a reduced level of electron transfer from the Eu 4f band to the V 3d xy band. This observation is ascribed to the reduced dispersion of the Eu 4f band, in contrast with our previous study on EuVO 2 H in which the empty V 3d xy bandwidth was manipulated by film thickness, manifesting the possibility of independent control over the d band and f band, an achievement unexplored in previous oxide research. Sr substitution not only decreases T C but also suppresses PMA. In addition, the application of high pressure to Eu 0.9 Sr 0.1 VO 2 H powder induces a continuous valence evolution of Eu, as opposed to that of pristine EuVO 2 H, which undergoes a first-order valence transition. This study offers possibilities for independent control of the electronic structure of systems containing both transition metals and rare earth elements.

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Magnetic phase diagram for the mixed-valence Eu oxide EuTi1−xAlxO3 (0

Cited by 18 publications

References 27 publications

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Local structure and magnetism of LaxEu1−xPO4
Martel¹,
Rakhmatullin²,
Baldoví³
et al. 2019
Phys. Rev. B
6
0
3
0
View full text Add to dashboard Cite

Intersite Charge Transfer through Eu 4f Band Engineering in Eu_1–xSr_xVO₂H Oxyhydride Films

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Magnetic phase diagram for the mixed-valence Eu oxide EuTi1−xAlxO3 (0

Cited by 18 publications

References 27 publications

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO2H Films

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO2H Films

Local structure and magnetism of LaxEu1−xPO4Martel1, Rakhmatullin2, Baldoví3 et al. 2019Phys. Rev. B6030View full textAdd to dashboardCite

Intersite Charge Transfer through Eu 4f Band Engineering in Eu1–xSrxVO2H Oxyhydride Films

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Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO₂H Films

Local structure and magnetism of LaxEu1−xPO4
Martel¹,
Rakhmatullin²,
Baldoví³
et al. 2019
Phys. Rev. B
6
0
3
0
View full text Add to dashboard Cite

Intersite Charge Transfer through Eu 4f Band Engineering in Eu_1–xSr_xVO₂H Oxyhydride Films