Resistance switching in epitaxial SrCoO<i>x</i> thin films

Togibasa, Octolia; Parwanta, Kadek Juliana; Acharya, Susant Kumar; Lee, Bo Wha; Jung, C. U.; Kim, Yeon Soo; Park, Bae Ho; Jeong, Huiseong; Park, Ji Yong; Cho, Michael; Park, Yun Daniel; Choi, Woo Seok; Kim, Dong Wook; Jin, Hyunwoo; Lee, Jun Young; Song, Seul Ji; Kang, Sung Jin; Kim, Miyoung; Hwang, Cheol Seong

doi:10.1063/1.4893323

Cited by 48 publications

(69 citation statements)

References 32 publications

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“…Because the lattice constants of both BM-SCO and SRO are slightly larger than that of STO, the as-grown films were under relatively smaller compressive strain. All these results are quite consistent with our previous XRD results on BM-SCO 25 .…”

Section: Resultssupporting

confidence: 93%

“…Recently, we observed the bipolar RS behavior of brownmillerite SrCoO x (BM-SCO) thin film and found that the forming voltage ( V F ) could be lower than the set voltage ( V S ) 25 . This, along with diverse temperature-dependent resistivity behaviors in the LRS and HRS, led us to a new type of switching mechanism based on a local topotactic phase transformation of the SCO from a brownmillerite to perovskite structure.…”

Section: Introductionmentioning

confidence: 99%

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Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Nallagatla

Acharya

et al. 2019

Sci Rep

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We had discovered novel resistance switching phenomena in SrCoOx epitaxial thin films. We have interpreted the results in terms of the topotactic phase transformation between their insulating brownmillerite phase and the conducting perovskite phase and the existence of a rather vertical conducting filament due to its inherent layered structure. However, the rough interface observed between the SrCoOx and the Au top electrode (area ~10000 μm2) was assumed to result in the observed fluctuation in key switching parameters. In order to verify the effect of rough interface on the switching performance in the SrCoOx device, in this work, we studied the resistive switching properties of a SrCoOx device by placing a Au-coated tip (end area ~0.5 μm2) directly on the film surface as the top electrode. The resulting device displayed much improved endurance and showed high uniformity in key switching parameters as compared to the device having a large top electrode area. A simulation result confirmed that the Au-coated tip provides a local confinement of the electrical field, resulting in confinement of oxygen ion distribution and therefore localization of the conducting filament. By minimizing other free and uncontrollable parameters, the designed experiment here provides the most direct and isolated evidence that the rough interface between electrode and ReRAM matrix is detrimental for the reproducibility of resistivity switching phenomena.

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Section: Resultssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Nallagatla

Acharya

et al. 2019

Sci Rep

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“…For example, brownmillerite SrCoO 2.5 (SCO) can undergo polymorphic phase transition under electric field control and has resistive switching behavior. 5,[7][8][9][10] Brownmillerite SrFeO x (SFO) with similar structure of SCO has been extensively studied due to its promising application in the fields of electrodes of fuel cell, magnetic storage, redox reaction catalyst, [11][12][13][14][15] etc. In addition, partial substitutions of the B specie of ABO 2.5 produce complex brownmillerite oxides such as Ca 2 FeAlO 5 , Ca 2 FeCoO 5 , etc.…”

Section: Introductionmentioning

confidence: 99%

Atomic occupancy mechanism in brownmillerite Ca₂FeAlO₅ from a thermodynamic perspective

Tao

Zhang

et al. 2019

J Am Ceram Soc

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Brownmillerite‐type oxides are a large family of structural and functional materials that are of great concern. In this study, the occupancy mechanism of Fe and Al ions in brownmillerite Ca2FeAlO5 is revealed and the specific configuration of Ca2FeAlO5 is proposed for the first time. Through the energy analysis of a series of conjectured models based on well‐defined ab initio calculations, we find that the distribution of Al and Fe in Ca2FeAlO5 follows the “homogeneous layer principle”, namely, Al and Fe tend to form homogeneous octahedral layers or tetrahedral chains rather than mixed layers or chains of two elements along the b axis. The theoretical Ca2FeAlO5 structure with specific atomic occupancy is proposed based on energy analysis and previous experiments, which is of fundamental significance for further study of its physical and chemical properties. Moreover, the influence of entropy increment on the stability of Ca2FeAlO5 crystal is clarified, which paves the way to investigate the structures and properties of Ca2FeAlO5 and other brownmillerite members.

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“…Brownmillerite oxides such as SrFeO 2.5 (BM-SFO) are of particular interest due to their wide range of physical properties including thermoelectricity, fast oxygen-ion transport, catalysis, and topotactic phase transformation at low temperatures 15,16 . These properties allow BM oxides to be exploited for extensive applications such as in solid-oxide fuel cells, sensors, membranes for oxygen separation, photon catalysis, and memristors [17][18][19] . BM oxides have a perovskite-derived structure with parallel rows of ordered oxygen vacancies that create tetrahedral chains directed along [101] pc in every second (010) pc octahedral plane.…”

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Effects of the Heterointerface on the Growth Characteristics of a Brownmillerite SrFeO2.5 Thin Film Grown on SrRuO3 and SrTiO3 Perovskites

Jo¹,

Nallagatlla

Acharya

et al. 2020

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Manipulation of the heterointerfacial structure and/or chemistry of transition metal oxides is of great interest for the development of novel properties. However, few studies have focused on heterointerfacial effects on the growth characteristics of oxide thin films, although such interfacial engineering is crucial to determine the growth dynamics and physical properties of oxide heterostructures. Herein, we show that heterointerfacial effects play key roles in determining the growth process of oxide thin films by overcoming the simple epitaxial strain energy. Brownmillerite (SrFeO 2.5 ; BM-SFO) thin films are epitaxially grown along the b-axis on both SrTiO 3 (001) and SrRuO 3 / SrTiO 3 (001) substrates, whereas growth along the a-axis is expected from conventional epitaxial strain effects originating from lattice mismatch with the substrates. Scanning transmission electron microscopy measurements and first principles calculations reveal that these peculiar growth characteristics of BM-SFO thin films originate from the heterointerfacial effects governed by their distinct interfacial structures. These include octahedral connectivity between dissimilar oxides containing different chemical species and a peculiar transition layer for BM-SFO/SrRuO 3 /SrTiO 3 (001) and BM-SFO/SrTiO 3 (001) heterostructures, respectively. These effects enable subtle control of the growth process of oxide thin films and could facilitate the fabrication of novel functional devices.

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Resistance switching in epitaxial SrCoOx thin films

Abstract: Articles you may be interested inStrain effect caused by substrates on phase separation and transport properties in Pr0.7(Ca0.8Sr0.2)0.3MnO3 thin films

Cited by 48 publications

References 32 publications

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Atomic occupancy mechanism in brownmillerite Ca₂FeAlO₅ from a thermodynamic perspective

Effects of the Heterointerface on the Growth Characteristics of a Brownmillerite SrFeO2.5 Thin Film Grown on SrRuO3 and SrTiO3 Perovskites

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Resistance switching in epitaxial SrCoOx thin films

Abstract: Articles you may be interested inStrain effect caused by substrates on phase separation and transport properties in Pr0.7(Ca0.8Sr0.2)0.3MnO3 thin films

Cited by 48 publications

References 32 publications

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

Atomic occupancy mechanism in brownmillerite Ca2FeAlO5 from a thermodynamic perspective

Effects of the Heterointerface on the Growth Characteristics of a Brownmillerite SrFeO2.5 Thin Film Grown on SrRuO3 and SrTiO3 Perovskites

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Atomic occupancy mechanism in brownmillerite Ca₂FeAlO₅ from a thermodynamic perspective