Oxygen vacancy mediated room temperature ferromagnetism in Cu-doped LiNbO3 thin films

Zhou, Xiaodong; Wang, Erlei; Lao, Xiaodong; Wang, Yongmei; Yuan, Huang

doi:10.1016/j.jmmm.2021.167775

Cited by 10 publications

(5 citation statements)

References 42 publications

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“…However, the oxygen vacancy concentration increased up to 43.6% during annealing in a reducing atmosphere. Similar results were also found elsewhere. , After annealing in an oxygen atmosphere, the oxygen vacancy concentration decreased to 27.5% again, implying the repeatability to create the LiNbO 3– x layers at the LNO surfaces.…”

Section: Resultssupporting

confidence: 89%

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Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Shen,

Tan,

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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Ferroelectric domain walls, agile nanoscale interfaces of polar order, can be selectively controlled by electric fields for their position, conformation, and function, which is ultimately the key to realizing novel low-energy memory and computing structures. LiNbO 3 single-crystal domain wall memory has the advantages of high operational speed, high integration density, and virtually unlimited endurance cycles, appearing as a good solution for the next generation of highly miniaturized low-energy memories. However, the etching process poses significant challenges in the nanofabrication and high-density integration of LiNbO 3 domain-wall memories.Here, we employed a hybrid etching technique to achieve smooth sidewalls with a 90°inclined angle, leading to a 24% reduction in the coercive field and a 2.5-fold increase in the linear domain wall current density with a retention time of more than 10 6 seconds and endurance of over 10 5 writing cycles. Combined with the results of X-ray diffraction patterns and X-ray photoelectric spectra, it is concluded that the excellent electrical performance is related to the formation of an oxygen-deficient LiNbO 3−x layer on the sidewall surface during the wet chemical etching process, which is a conductive layer that reduces the thickness of the "dead" layer between the side electrodes and the LiNbO 3 cell and rectifies the diode-like wall currents with an onset voltage reduced from 1.23 to 0.28 V. These results prove the high-density integration of ferroelectric domain-wall memories at the nanoscale and provide a new strategy applicable to the development of LiNbO 3 photonic devices.

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Section: Resultssupporting

confidence: 89%

“…Similar results were also found elsewhere. 47,48 After annealing in an oxygen atmosphere, the oxygen vacancy concentration decreased to 27.5% again, implying the repeatability to create the LiNbO 3−x layers at the LNO surfaces. The influence of defects on the properties of ferroelectric DWs has long been recognized.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Shen,

Tan,

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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“…Attention is firstly paid to the valence states of Li, O, and Er in the grown films. In Figure 2A, the XPS peak at 54.3 eV can be attributed to monovalent Li ion (Li + ) 25 . In Figure 2B, two XPS peaks originating from negative divalent O ion (O 2− ) can be resolved.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure 2A, the XPS peak at 54.3 eV can be attributed to monovalent Li ion (Li + ). 25 In Figure 2B, two XPS peaks originating from negative divalent O ion (O 2− ) can be resolved. One is located at ∼530 eV and associated with the metal-oxygen bond.…”

Section: Constituent Element Valence States and Defectsmentioning

confidence: 99%

Growth of Er³⁺‐doped LiNbO₃ thin‐film on LiTaO₃ by e‐beam evaporation

Xue,

Yang,

Zhang

2023

J Am Ceram Soc.

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Growth of Er3+‐doped 100‐nm thick LiNbO3(LN) films on Z‐cut LiTaO3(LT) single‐crystal by e‐beam evaporation and in‐situ anneal at 600–800°C was studied. Crystalline phase, crystallographic orientation, Er3+ spectroscopic properties, constituent element valence states, defects, Er3+ concentration and stoichiometry of the films were characterized. The results show that the films are in LN single‐crystal state and orient along with c crystallographic axis. Constituent elements Li, O and Er are present in their respective single valence states Li+, O2−, Er3+, while the Nb is in two valence states Nb5+ and Nb4+. The films have Li2O‐contents around congruent point. Antisite(NbLi4+) is the major defect. Its concentration decreases, while Li2O‐content, crystallinity degree, and fluorescence intensity increase with increased growth temperature. The presence of Er3+ in the grown films is in the form of LN crystalline phase. Its concentration is considerably lower than that in initial target material because of lower e‐beam evaporation efficiency of heavy Er3+.

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“…There are only a limited number of works where the implantation of magnetic 3d-metal ions to LiNbO 3 has been studied (see, for instance, Refs. [23][24][25][26][27][28][29]). To our knowledge, in these papers mostly the creation of substitution centers in the crystal structure of LiNbO 3 was addressed, and the impurity concentration was insufficient for precipitation to nanoparticles in the irradiated layer.…”

Section: Introductionmentioning

confidence: 99%

Unusual Compositions of Fe-Nb Alloy Precipitates in Iron-Implanted LiNbO3

et al. 2023

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The results of a study of heavy implantation of a LiNbO3 crystal with iron ions are reported for the first time. The X-cut LiNbO3 substrate was implanted with 40-keV Fe+ ions to the fluence of 1.5·1017 ions/cm2. The sample reveals pronounced ferromagnetic properties at room temperature. However, the ferromagnetic response observed in the iron-implanted LiNbO3 differs from the magnetic behavior of other oxides implanted with iron ions under the same conditions. This difference occurs from the unusual magnetic phase composition of the implanted surface layer of the LiNbO3 in which the iron implant precipitates in the form of the nanoscale alloy of metallic iron with niobium. Based on Mössbauer spectroscopy data, we estimated the Nb content in the ion-synthesized nanosized alloy as ~12 at.%, which is much higher than the solid solubility limit of Nb in bulk Fe.

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Oxygen vacancy mediated room temperature ferromagnetism in Cu-doped LiNbO3 thin films

Cited by 10 publications

References 42 publications

Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Growth of Er³⁺‐doped LiNbO₃ thin‐film on LiTaO₃ by e‐beam evaporation

Unusual Compositions of Fe-Nb Alloy Precipitates in Iron-Implanted LiNbO3

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Oxygen vacancy mediated room temperature ferromagnetism in Cu-doped LiNbO3 thin films

Cited by 10 publications

References 42 publications

Hybrid Dry and Wet Etching of LiNbO3 Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Hybrid Dry and Wet Etching of LiNbO3 Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Growth of Er3+‐doped LiNbO3 thin‐film on LiTaO3 by e‐beam evaporation

Unusual Compositions of Fe-Nb Alloy Precipitates in Iron-Implanted LiNbO3

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Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Hybrid Dry and Wet Etching of LiNbO₃ Domain-Wall Memory Devices with 90° Etching Angles and Excellent Electrical Properties

Growth of Er³⁺‐doped LiNbO₃ thin‐film on LiTaO₃ by e‐beam evaporation