Direct observation of oxygen vacancy-driven structural and resistive phase transitions in La2/3Sr1/3MnO3

Yao, Lide; Inkinen, Sampo; Dijken, Sebastiaan van

doi:10.1038/ncomms14544

Cited by 161 publications

(171 citation statements)

References 39 publications

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“…The measurements were performed along the direction indicated by the arrows, and spectra were recorded every ≈5 Å (Figure 4c for LRS and Figure 4d for HRS). Further in-suit TEM measurements can be investigated by directly imaging of atomic-scale dynamic processes and their real-time impact on resistance change, [42][43][44] which can give us an in-depth understanding of oxygen vacancy driven RS behavior observed here. However, compared with LRS, the main peak (marked by the red arrow) in HRS O K-edge EELS shifts a little to the right, implying lower Ni valence in HRS.…”

Section: Wwwadvelectronicmatdementioning

confidence: 99%

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Wang

Zhang

Chang

et al. 2017

Adv Elect Materials

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into the corner-shared NiO 6 octahedra network (Figure 1a) modifies the NiO bond length and angle, affecting the electronic bandwidth and physical properties of RNiO 3 . Furthermore, Ni 3+ is reduced2 2x and electrons are doped into RNiO 3 via oxygen vacancies. [2,10] Previous works have shown that oxygen vacancies play an important role in perovskite heterostructures. [10][11][12][13][14][15] External electric field could induce the migration of the oxygen vacancy in the perovskite films and then change the interfacial barrier in heterostructures, leading resistive switching (RS) behavior. We expect such effect to be more prominent in nickelates-based ones due to their smaller oxygen vacancy formation energy. This motivates us to explore the possibility of electrochemically driven RS in nickelates systems. Our finding reveals giant bipolar RS behavior in Pt/RNiO 3 / Nb-SrTiO 3 heterostructures with ON/OFF ratio of about 10 5 at room temperature. The effect is tunable by varying the oxygen content or changing the rare earth element in the sample.A set of GdNiO 3−x films on Nb-SrTiO 3 substrates were grown under different deposition oxygen pressures (P(O 2 )) of 100, 20, 2, and 0.2 mTorr, respectively. The film thickness was fixed at 10 nm. The samples are labeled as D1-D4, in the order of decreasing P(O 2 ) from 100 to 0.2 mTorr. The influence of P(O 2 ) on our samples can be seen in Figure 1 (also see Figure S1 in the Supporting Information). Figure 1b displays the typical current-voltage (I-V) characteristics of the samples, and the inset is the schematic setup for the measurements. The arrows in Figure 1b represent the sequence of voltage sweeps. Sample D1 shows nonlinear I-V characteristics with negligible RS effect. In contrast, sample D4 shows obvious "counterclockwise" bipolar RS behavior. Here, we define the upper and lower branches of the I-V curves as low resistance state (LRS or ON) and high resistance state (HRS or OFF), respectively. Sample D4 switches from HRS (LRS) to LRS (HRS) when a forward (reverse) bias is applied to Pt, and this is defined as the set (reset) process. It should be pointed out that this counterclockwise I-V hysteresis in our asymmetrical devices is different from ferroelectric switchable diode behavior, [16][17][18] which is mainly controlled by the ferroelectric polarization. Since the formation energy of oxygen vacancy is low in nikelates, [9] we expect more oxygen vacancies in the GdNiO 3−x film than in the Nb-SrTiO 3 substrate. Scanning transmission electronThe rich phase diagrams and peculiar physical properties of rare earth perovskite nickelates (RNiO 3 ) have recently attracted much attention. Their electronic structures are highly sensitive to carrier density and bandwidth due to Mott physics. Here, the electrochemically driven giant resistive switching in Pt/RNiO 3 /Nb-SrTiO 3 heterostructures is reported. Systematic investigation confirms that oxygen vacancies migration modifies the interfacial barrier at the RNiO 3 /Nb-SrTiO 3 interface and causes the resistive swit...

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Section: Wwwadvelectronicmatdementioning

confidence: 99%

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Wang

Zhang

Chang

et al. 2017

Adv Elect Materials

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“…[38] With the above understanding of the RS mechanism, we believe that the nanoscale topotactic phase transformation between BM-SFO and PV-SFO can enable us to aggressively downscale the SFO-based RS memory cells. [38] With the above understanding of the RS mechanism, we believe that the nanoscale topotactic phase transformation between BM-SFO and PV-SFO can enable us to aggressively downscale the SFO-based RS memory cells.…”

mentioning

confidence: 96%

Nanoscale Topotactic Phase Transformation in SrFeO_x Epitaxial Thin Films for High‐Density Resistive Switching Memory

Tian

Fan

et al. 2019

Advanced Materials

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Oxygen stoichiometry plays a crucial role in determining the crystalline structure and physical properties of transition metal oxides (TMOs). Tuning the oxygen content via an electrochemical redox reaction can effectively manipulate the functionalities of TMOs, which is harnessed in many cutting-edge energy and information technologies such as fuel cells, [1] rechargeable batteries, [2] supercapacitors, [3] and memory devices. [4] The redox reaction in certain TMOs can be enabled by a so-called topotactic phase transformation, manifesting itself as the insertion/release of a large amount of oxygen ions without breaking the lattice framework. For example, for an ABO 3 perovskite (PV) phase, upon forming ordered oxygen vacancy channels in its lattice, it transforms into an ABO 2.5 brownmillerite (BM) phase. Along with the structural change, many intriguing physical phenomena emerge owing to the couplings between lattice, charge, and Resistive switching (RS) memory has stayed at the forefront of next-generation nonvolatile memory technologies. Recently, a novel class of transition metal oxides (TMOs), which exhibit reversible topotactic phase transformation between insulating brownmillerite (BM) phase and conducting perovskite (PV) phase, has emerged as promising candidate materials for RS memories. Nevertheless, the microscopic mechanism of RS in these TMOs is still unclear. Furthermore, RS devices with simultaneously high density and superior memory performance are yet to be reported. Here, using SrFeO x as a model system, it is directly observed that PV SrFeO 3 nanofilaments are formed and extend almost through the BM SrFeO 2.5 matrix in the ON state and are ruptured in the OFF state, unambiguously revealing a filamentary RS mechanism. The nanofilaments are ≈10 nm in diameter, enabling to downscale Au/ SrFeO x /SrRuO 3 RS devices to the 100 nm range for the first time. These nanodevices exhibit good performance including ON/OFF ratio as high as ≈10 4 , retention time over 10 5 s, and endurance up to 10 7 cycles. This study significantly advances the understanding of the RS mechanism in TMOs exhibiting topotactic phase transformation, and it also demonstrates the potential of these materials for use in high-density RS memories.

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“…[13] We provide an explanation supported on strong evidences for an oxygen migration-mediated RS effect in LSMO films (and extensible to other metallic complex oxides, such as cuprates and nickelates [10] ), while material engineering through the use of a bilayer system with an oxygen buffer layer offers novel functional devices as the proof-of-concept 3-T device presented. [18] The proof-of-concept that we report here provides a device realization after understanding and controlling the volume switching process on a mixed-valence-mixed conductor model system as La 0.8 Sr 0.2 MnO 3 in which the switched thickness of up to 40 nm is demonstrated. The huge potential of Mott transitions for envisioning new devices, with particular focus on 3-T devices, has attracted some recent interest (including ionic liquid gating).…”

Section: Introductionmentioning

confidence: 84%

“…[10] In this sense, this is the first time that a direct evidence of the impact of the atmosphere has on the resistive switching properties of manganites. [18] These previous reports pointed toward a bulk limited conduction mechanism in LSMO films rather than a Schottky barrier mechanism. [18] These previous reports pointed toward a bulk limited conduction mechanism in LSMO films rather than a Schottky barrier mechanism.…”

Section: Volume Resistive Switching Mechanismmentioning

confidence: 98%

“…While in ambient conditions a large resistance ratio from HRS to LRS of r amb = R HRS /R LRS ≈ 10 3 -10 4 is found, the ratio observed in vacuum, r vac , is extremely diminished down to a value of r vac ≈ 2. [18,26,27] Systematic pulsing studies and adequate modelling need to be carried out to understand the balance of both contributions in determining the switching kinetics. For a deeper understanding of the phenomenon, I-V curves were also acquired at different oxygen partial pressures (Figure 1c).…”

Section: Atmosphere Dependent I-v Curvesmentioning

confidence: 99%

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Engineering Oxygen Migration for Homogeneous Volume Resistive Switching in 3‐Terminal Devices

Gonzalez‐Rosillo

Ortega-Hernandez

Arndt

et al. 2019

Adv Elect Materials

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the community to enable their widespread use. [5] However, there are still several fundamental and practical issues to be addressed in order to fulfill industrial requirements of reproducibility and reliability of the manufactured devices. That is the case of actual devices relying on widely used filamentary-type resistive switching (RS) mechanism, [6] where the main difficulty lies on the random formation (and subsequent rupture) of the aforementioned filament (which determines whether the device is in an ON or an OFF state, respectively), or leakage currents that could arise in the devices, as well as other issues intrinsically arising from the high nonlinearity electric field dynamics of the materials. [7] Additionally, there is the need of a full comprehension of the underlying physical mechanism in some of the active RS materials, [6,7] to provide the final boost from the material's perspective to engineering of the devices.From the materials point of view, simple binary oxides are widely studied and are viable materials for its simplicity, complementary metal-oxide-semiconductor (CMOS) technology compatibility, and promising performance, and thorough research is being conducted to tackle the issues exposed above. Alternatively, the interest of strongly correlated systems with functional properties, such as metal-insulator transition (MIT), is growing [8][9][10] and heading toward applications. The exotic intrinsic properties of these complex oxides could lead to novel design of devices (for a complete review, see ref.[8]) with enhanced performance and functionalities, specially through the control of oxygen kinetics, which has dramatic implications on the functional properties. [11] Previous studies have related the resistive switching effect in metallic perovskite oxides to their intrinsic MIT properties even through film thickness up to 10 nm suggesting a volume resistive switching mechanism. [10,12,13,36] Oxygen release from the crystal lattice would generate oxygen vacancies in the system, concomitant with a decrease of the charge carriers in the system and a valence state reduction (Mn +4 → Mn 3+ ). The advantages of showing bulk RS characteristics in these metallic perovskite oxides, instead of usual filament or filamentary ones in dielectric oxides, are i) more robust switching performance, ii) highly spatial control of the switching event, iii) easier circuit integration due to the initial metallic character of the films, and iv) high reproducibility of the effect, since it is based on an intrinsic property of the material itself.Resistive switching effects are in a superb position to tackle the challenges for the near future of nanoelectronics and neuromorphics. Material-wise, the outstanding properties of strongly correlated metallic perovskite oxides, in particular, those displaying metal-insulator transition can be exploited for a new generation of devices based on a volume resistive switching (VRS) phenomenon beyond filamentary and interface ideas. This study reports a full description of this ...

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Direct observation of oxygen vacancy-driven structural and resistive phase transitions in La2/3Sr1/3MnO3

Cited by 161 publications

References 39 publications

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Nanoscale Topotactic Phase Transformation in SrFeO_x Epitaxial Thin Films for High‐Density Resistive Switching Memory

Engineering Oxygen Migration for Homogeneous Volume Resistive Switching in 3‐Terminal Devices

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Direct observation of oxygen vacancy-driven structural and resistive phase transitions in La2/3Sr1/3MnO3

Cited by 161 publications

References 39 publications

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Nanoscale Topotactic Phase Transformation in SrFeOx Epitaxial Thin Films for High‐Density Resistive Switching Memory

Engineering Oxygen Migration for Homogeneous Volume Resistive Switching in 3‐Terminal Devices

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Nanoscale Topotactic Phase Transformation in SrFeO_x Epitaxial Thin Films for High‐Density Resistive Switching Memory