Concurrent transition of ferroelectric and magnetic ordering near room temperature

Ko, K.-T.; Jung, Minsu; He, Qing; Lee, Jin Hong; Woo, Chang Su; Chu, Kanghyun; Seidel, Jan; Jeon, Byung Gu; Oh, Yoon Seok; Kim, Kee Hoon; Liang, Wen I.; Chen, Hsiang Jung; Chu, Ying‐Hao; Jeong, Yoon Hee; Ramesh, R.; Park, Jae Hoon; Yang, Chan−Ho

doi:10.1038/ncomms1576

Cited by 154 publications

(79 citation statements)

References 36 publications

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“…10,11 Moreover, the growth of BFO on (001) LaAlO 3 substrates (aB3.79 Å ) stabilizes a new highly elongated phase with large tetragonality (c/aB1.23) 7,12 in which the structural, magnetic and ferroelectric properties are largely modified. [13][14][15][16][17][18] The T N greatly decreases to B370 K and ferroelectric reorientation transition accompanied with structural phase transition between M C -and M A -type monoclinic structures occurs concomitantly at the T N . 13,15,18 With increasing thickness, the mixed-phase regions are formed and composed of the highly elongated phase (T-phase) and a third polymorphic phase with relatively smaller c-axis lattice parameter (R 0 -phase).…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15][16][17][18] The T N greatly decreases to B370 K and ferroelectric reorientation transition accompanied with structural phase transition between M C -and M A -type monoclinic structures occurs concomitantly at the T N . 13,15,18 With increasing thickness, the mixed-phase regions are formed and composed of the highly elongated phase (T-phase) and a third polymorphic phase with relatively smaller c-axis lattice parameter (R 0 -phase). Because the relevant competing phases have quite different c-axis lattice parameters, as much as 10% while still being fully epitaxial without cracks or grain boundaries, electric control of the tetragonal-rhombohedral (T-R 0 ) phase boundary (T-R 0 PB) holds promise for very large electromechanical responses.…”

Section: Introductionmentioning

confidence: 99%

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Electric control of straight stripe conductive mixed-phase nanostructures in La-doped BiFeO3

et al. 2014

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This study examines the atomic force microscope (AFM) tip-based electrical formation of tens of microns long stripe (and B100 nm wide) inorganic one-dimensional nanostructures based on the morphotropic phase boundary of La-doped BiFeO 3 epitaxial thin films. The substitution of Lanthanum into bismuth ferrite not only produces the formation of straight stripe mixedphase patterns but also improves the spatial continuity drastically by two orders of magnitude. We create, switch and erase stripe nanostructures in a reversible and deterministic way. We demonstrate that electrically formed areas with a nearly single variant alignment can be overwritten with different alignments repeatedly, which reflects the reversible and nonvolatile nature of the switching process. In addition, we explore the functionality of the created nanostructures by clarifying ferroelectric polarizations and observing the improvement of the electronic conduction at the phase boundary. Our findings provide new pathways to one-dimensional rewritable nanostructures and inspire researchers to conceive various multifunctional devices by combining the superb electromechanical property with their unique interfacial electronic conduction properties at nanoscale phase boundaries.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electric control of straight stripe conductive mixed-phase nanostructures in La-doped BiFeO3

et al. 2014

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“…[1][2][3][4][5][6][7] Bismuth ferrite is a room temperature multiferroic perovskite exhibiting antiferromagnetism that is coupled with ferroelectric order. 8 Below the Curie temperature, bulk BFO is considered to have a rhombohedral R3c space group structure that allows antiphase octahedral tilting and ionic displacements from the center of symmetry along the [111] pseudocubic direction.…”

Section: Introductionmentioning

confidence: 99%

Enhanced conductivity at orthorhombic–rhombohedral phase boundaries in BiFeO3 thin films

et al. 2016

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Enhanced properties in modern functional materials can often be found at structural transition regions, such as morphotropic phase boundaries (MPB), owing to the coexistence of multiple phases with nearly equivalent energies. Strain-engineered MPBs have emerged in epitaxially grown BiFeO 3 (BFO) thin films by precisely tailoring a compressive misfit strain, leading to numerous intriguing phenomena, such as a massive piezoelectric response, magnetoelectric coupling, interfacial magnetism and electronic conduction. Recently, an orthorhombic-rhombohedral (O-R) phase boundary has also been found in tensile-strained BFO. In this study, we characterise the crystal structure and electronic properties of the two competing O and R phases using X-ray diffraction, scanning probe microscope and scanning transmission electron microscopy (STEM). We observe the temperature evolution of R and O domains and find that the domain boundaries are highly conductive. Temperature-dependent measurements reveal that the conductivity is thermally activated for R-O boundaries. STEM observations point to structurally wide boundaries, significantly wider than in other systems. Therefore, we reveal a strong correlation between the highly conductive domain boundaries and structural material properties. These findings provide a pathway to use phase boundaries in this system for novel nanoelectronic applications. INTRODUCTIONMultiferroic BiFeO 3 (BFO) has attracted great interest as a promising lead-free functional material owing to its key properties, including electromechanical and magnetoelectric coupling, domain wall conductance, bias-induced semiconductor-insulator transitions and photovoltaic effects. 1-7 Bismuth ferrite is a room temperature multiferroic perovskite exhibiting antiferromagnetism that is coupled with ferroelectric order. 8 Below the Curie temperature, bulk BFO is considered to have a rhombohedral R3c space group structure that allows antiphase octahedral tilting and ionic displacements from the center of symmetry along the [111] pseudocubic direction. 9,10 The recent discovery of a strain-induced morphotropic phase boundary in BFO films grown on (001) LaAlO 3 has attracted further interest with the compressive strain imposed by an underlying substrate stabilizing a tetragonally distorted phase. 11-17 Mixed-phase regions exhibit the coexistence of both R-and T-like phases with the ability to selectively switch between the two phases by an external electric field and force. [18][19][20][21][22] Interestingly, the strong correlation between T-R interfaces and their enhanced properties, such as the finding of a large electric-field-induced strain 23 and a giant piezoelectric d 33 coefficient, led to extensive studies of bismuth ferrite films under compressive strain by both experimental and theoretical approaches. Moreover, a correlation between the elasticity at the T-R interfaces and electronic conduction was also reported. 24 Triggered by

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“…19 The magnetic contribution to the XLD can be determined by monitoring the linear dichroism as a function of temperature: the magnetic XLD is expected to decrease rapidly when the sample is heated to the Néel temperature (T N ). 25,27 A reduction of the XLD with increasing temperature is shown in the inset of Figure 3a for the highly strained BFO films. Temperature-dependent I LD at the Fe-L 2 edge is shown in Figure 3a, where I LD is the integration of the absolute XLD signal, that is, |E//a-E//c| 2 from 721 eV to 726 eV (see the inset) normalized to the value measured at room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…27,28 For d 5 systems, the primary interaction is between the two filled e g orbitals via the oxygen 2p σ-bonding orbitals. The , where the inset figure shows the soft X-ray absorption (XA) spectra measured at 27 and 300°C at the Fe L 3 edge with the X-ray linear polarization E parallel to c (E//c, orange line) and perpendicular to c (E⊥c, black line).…”

Section: Resultsmentioning

confidence: 99%

Electrically enhanced magnetization in highly strained BiFeO3 films

et al. 2016

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The control of magnetism via an electric field has attracted substantial attention because of potential applications in magnetoelectronics, spintronics and high-frequency devices. In this study, we demonstrate a new approach to enhance and control the magnetization of multiferroic thin film by an electric stimulus. First, to reduce the strength of the antiferromagnetic superexchange interaction in BiFeO 3 , we applied strain engineering to stabilize a highly strained phase. Second, the direction of the ferroelectric polarization was controlled by an electric field to enhance the Dzyaloshinskii-Moriya interaction in the highly strained BiFeO 3 phase. Because of the magnetoelectric coupling in BiFeO 3 , a strong correlation between the modulated ferroelectricity and enhanced magnetization was observed. The tunability of this strong correlation by an electric field provides an intriguing route to control ferromagnetism in a single-phase multiferroic.

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Concurrent transition of ferroelectric and magnetic ordering near room temperature

Cited by 154 publications

References 36 publications

Electric control of straight stripe conductive mixed-phase nanostructures in La-doped BiFeO3

Electric control of straight stripe conductive mixed-phase nanostructures in La-doped BiFeO3

Enhanced conductivity at orthorhombic–rhombohedral phase boundaries in BiFeO3 thin films

Electrically enhanced magnetization in highly strained BiFeO3 films

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