Effect of the thickness of BiFeO3 layers on the magnetic and electric properties of BiFeO3/La0.7Sr0.3MnO3 heterostructures

Wang, Le; Wang, Zhen; Jin, Kui-juan; Li, Jianqi; Yang, Huai; Wang, Can; Zhao, Ruoxi; Lü, Huibin; Guo, Haizhong; Yang, Guo‐Zhen

doi:10.1063/1.4811439

Cited by 29 publications

(19 citation statements)

References 30 publications

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“…This motivates us to explore the possibility of electrochemically driven RS in nickelates systems. 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. The effect is tunable by varying the oxygen content or changing the rare earth element in the sample.…”

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confidence: 61%

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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confidence: 61%

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Wang

Zhang

Chang

et al. 2017

Adv Elect Materials

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“…[32,33] Briefly, we used (001)-oriented STO single crystal samples (5 × 5 mm 2 , 0.5 mm thickness) as substrates. [32,33] Briefly, we used (001)-oriented STO single crystal samples (5 × 5 mm 2 , 0.5 mm thickness) as substrates.…”

Section: Methodsmentioning

confidence: 99%

“…[28,29] Besides, STO can help to precisely control the crystal panel of functional perovskite oxides at atomic scale, because of its good lattice matching with them. [32,33] BFO surface potential after polarization could reach to the amplitude of endogenous electronegative potentials found on bone defect walls. [31] To control the direction of electric potentials on nanofilm implant surfaces, we used the epitaxial growth technique to organize the crystal panel of BFO at the atomic level.…”

Section: Introductionmentioning

confidence: 90%

Built‐In Electric Fields Dramatically Induce Enhancement of Osseointegration

Liu

Zhang

Cao

et al. 2017

Adv Funct Materials

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Rapid and effective osseointegration is a great challenge in clinical practice. Endogenous electronegative potentials spontaneously appear on bone defect sites and mediate healing. Thus, bone healing can potentially be stimulated using physiologically relevant electrical signals in implants. However, it is difficult to directly introduce physiologically relevant electric fields in bone tissue. In this study, built-in electric fields are established between electropositive ferroelectric BiFeO 3 (BFO) nanofilms and electronegative bone defect walls to trigger implant osseointegration and biological healing. Epitaxial growth technique is used to organize the crystal panel at an atomic scale, and ferroelectric polarization of BFO nanofilms matching the amplitude and direction of endogenous electric potentials on bone defect walls is achieved. In the presence of built-in electric fields, implants with BFO nanofilms with downward polarization (BFO+) show rapid and superior osseointegration in the rat femur. The mechanism of this phenotypic osteogenic behavior is further studied by protein adsorption and stem cell behavior in different time points. BFO+ promotes protein adsorption and mesenchymal stem cell (MSC) attachment, spreading, and osteogenic differentiation. Custom-designed PCR array examination shows sequentially initiated Ca 2+ signaling, cell adhesion and spreading, and PI3K-AKT signaling in MSCs. The results of this study provide a novel strategy for the development of implant surface modification technology.

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“…BiFeO 3 (BFO) has drawn considerable attention, since it has been found hitherto as the only single-phase room-temperature magnetoelectric multiferroic1234567. Meanwhile, tremendous activities have been engaged to study BFO thin films, which may meet the needs for microelectronic information storage devices89101112.…”

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confidence: 99%

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

Wang

Jin

Guo

et al. 2016

Sci Rep

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BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films.

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Effect of the thickness of BiFeO3 layers on the magnetic and electric properties of BiFeO3/La0.7Sr0.3MnO3 heterostructures

Cited by 29 publications

References 30 publications

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

Built‐In Electric Fields Dramatically Induce Enhancement of Osseointegration

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

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