Spatially Resolved Ferroelectric Domain-Switching-Controlled Magnetism in Co40Fe40B20/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Multiferroic Heterostructure

Li, Peisen; Zhao, Yonggang; Zhang, Sen; Chen, Aitian; Li, Dalai; Ma, Jing; Liu, Yan; Pierce, Daniel T.; Unguris, John; Piao, Hong‐Guang; Zhang, Huiyun; Zhu, M. H.; Zhang, Xiaozhong; Han, X. F.; Pan, Mengchun; Nan, Ce‐Wen

doi:10.1021/acsami.6b13620

Cited by 43 publications

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“…1(b)]. This is very convenient to disentangle magnetoelectric effects since they may result in anisotropic changes of magnetic anisotropy as happens in other heterostructures, such as Co 40 Fe 40 B 20 /PMN-PT [15,24,25]. Figure 3 shows the VSM characterization as a function of the applied voltage while applying the in-plane magnetic field along [001] [i.e., 0°configuration, Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, since the strain largely vanishes after removal of the external electric field, the magnetic changes are generally volatile (i.e., not permanent) when the applied electric field is removed [15,30,31,34]. Furthermore, the magnetostrictive coupling is a function of the square of magnetization (M ) and electric polarization (P) and, therefore, in principle, the sign of M cannot be switched with P. However, strong asymmetries with voltage have been observed in the magnetic properties of FM-PMN-PT heterostructures, eventually resulting in a "looplike"-controlled magnetization, and therefore, in permanent changes (i.e., nonvolatile) [23][24][25][26][27]. Thus, if the magnitude of P at + V applied is different from that at − V applied , the magnitude of M can be changed with voltage polarity.…”

Section: Introductionmentioning

confidence: 99%

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Disentangling Highly Asymmetric Magnetoelectric Effects in Engineered Multiferroic Heterostructures

et al. 2019

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One of the main strategies to control magnetism by voltage is the use of magnetostrictive-piezoelectric hybrid materials, such as ferromagnetic-ferroelectric heterostructures. When such heterostructures are subjected to an electric field, piezostrain-mediated effects, electronic charging, and voltage-driven oxygen migration (magnetoionics) may simultaneously occur, making the interpretation of the magnetoelectric effects not straightforward and often leading to misconceptions. Typically, the strain-mediated magnetoelectric response is symmetric with respect to the sign of the applied voltage because the induced strain (and variations in the magnetization) depends on the square of the ferroelectric polarization. Conversely, asymmetric responses can be obtained from electronic charging and voltage-driven oxygen migration. By engineering a ferromagnetic-ferroelectric hybrid consisting of a magnetically soft 50-nm thick Fe 75 Al 25 (at. %) thin film on top of a 110-oriented Pb(Mg 1/3 Nb 2/3)O 3-32PbTiO 3 ferroelectric crystal, a highly asymmetric magnetoelectric response is obtained and the aforementioned magnetoelectric effects can be disentangled. Specifically, the large thickness of the Fe 75 Al 25 layer allows dismissing any possible charge accumulation effect, whereas no evidence of magnetoionics is observed experimentally, as expected from the high resistance to oxidation of Fe 75 Al 25 , leaving strain as the only mechanism to modulate the asymmetric magnetoelectric response. The origin of this asymmetric strain-induced magnetoelectric effect arises from the asymmetry of the polarization reversal in the particular crystallographic orientation of the ferroelectric substrate. These results are important to optimize the performance of artificial multiferroic heterostructures.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Disentangling Highly Asymmetric Magnetoelectric Effects in Engineered Multiferroic Heterostructures

et al. 2019

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“…Similar to the device structure, an ellipticalshaped CoFeB disk of 18 × 6 m 2 was built and discretized in the computational cells of 10 nm × 10 nm. The saturation magnetization, M S , was 1200 emu cm −3 , and the uniform exchange constant, A, was 2.8 × 10 −11 J m −1 (37). To simulate the domain structures of the free layer of the MTJ under voltages, a single domain along the [100] direction of PMNPT (the pinning direction of the MTJs) was set as the initial state.…”

Section: Micromagnetic Simulations On the Magnetization Evolutionmentioning

confidence: 99%

Full voltage manipulation of the resistance of a magnetic tunnel junction

et al. 2019

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One of the motivations for multiferroics research is to find an energy-efficient solution to spintronic applications, such as the solely electrical control of magnetic tunnel junctions. Here, we integrate spintronics and multiferroics by depositing MgO-based magnetic tunnel junctions on ferroelectric substrate. We fabricate two pairs of electrodes on the ferroelectric substrate to generate localized strain by applying voltage. This voltage-generated localized strain has the ability to modify the magnetic anisotropy of the free layer effectively. By sequentially applying voltages to these two pairs of electrodes, we successively and unidirectionally rotate the magnetization of the free layer in the magnetic tunnel junctions to complete reversible 180° magnetization switching. Thus, we accomplish a giant nonvolatile solely electrical switchable high/low resistance in magnetic tunnel junctions at room temperature without the aid of a magnetic field. Our results are important for exploring voltage control of magnetism and low-power spintronic devices.

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“…One of the main goals in the study of magnetoelectrics is the electrical control of magnetism [1][2][3][4][5] . This has been previously demonstrated using bulk multiferroic materials [6][7][8][9][10] ; strained multiferroic composites 11 or multilayers 12 ; ferromagnetic films in which a gate controls semiconductor carrier density [13][14][15][16] or interfacial electronic structure [17][18][19] ; ferromagnetic films to which a magnetoelectric (ME) material imparts exchange bias 20 ; and ferromagnetic films to which a ferroelectric material imparts strain [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] , charge [36][37][38][39] and/or exchange bias [37][38][39] . Proposals for electric-write magnetic-read data-storage devices [40][41][42] focus on patterned ferromagnetic films that experience strain or exchange bias from ferroelectrics that are typica...…”

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confidence: 99%

“…Therefore PMN-PT is widely exploited in ME heterostructures 22,26,28,29,32,34,35,46,47 , and more generally in commercial electromechanical devices such as transducers and actuators.…”

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confidence: 99%

Shear-strain-mediated magnetoelectric effects revealed by imaging

et al. 2019

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Large changes in the magnetization of ferromagnetic films can be electrically driven by non-180 ferroelectric domain switching in underlying substrates, but the shear components of the strains that mediate these magnetoelectric effects have not been considered so far. Here we reveal the presence of these shear strains in a polycrystalline film of Ni on a 0.68Pb(Mg 1/3 Nb 2/3)O 3-0.32PbTiO 3 substrate in the pseudo-cubic (011) pc orientation. Although vibrating sample magnetometry records giant magnetoelectric effects that are consistent with the hitherto expected 90 rotations of a global magnetic easy axis, high-resolution vector maps of magnetization (constructed from photoemission electron microscopy data, with contrast from x-ray magnetic circular dichroism) reveal that the local magnetization typically rotates through smaller angles of 62-84. This shortfall with respect to 90 is a consequence of the shear strain associated with ferroelectric domain switching. The non-orthogonality represents both a challenge and an opportunity for the development and miniaturization of magnetoelectric devices. Wisconsin-Madison (J.-M. H.). D. P. acknowledges funding from the Agència de Gestió d'Ajuts Universitaris i de Recercaa-Generalitat de Catalunya (Grant 2014 BP-A 00079). We thank Diamond Light Source for time on beamline I06 (proposal SI-8876), and we thank Sen Zhang for discussions. Author contributions M.G. initiated the study. M.G. and N.D.M. led the project with S.S.D. R.M., R.P.C. and C.H.W.B. were responsible for the growth of thin film Ni. The collection and preliminary analysis of PEEM data were performed by M.G., with assistance from X.M., L.C.P and W.Y. All other experimental work was performed by M.G. F.M. and S.S.D. were responsible for constructing PEEM vector maps, and the subsequent pixel by pixel analysis. D.P. performed image and data processing. N.D.M. proposed the pixel-by-pixel analysis of PEEM vector maps that led to the key finding of sub 90° magnetization rotation. J. M.H. identified and calculated the shear strain that accompanies ferroelectric domain switching in PMN-PT. M.G. identified the resulting principal axes of strain and hence magnetic easy axes. M.G. and N.D.M. interpreted the observed magnetoelectric effects.

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Spatially Resolved Ferroelectric Domain-Switching-Controlled Magnetism in Co₄₀Fe₄₀B₂₀/Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃ Multiferroic Heterostructure

Cited by 43 publications

References 45 publications

Disentangling Highly Asymmetric Magnetoelectric Effects in Engineered Multiferroic Heterostructures

Disentangling Highly Asymmetric Magnetoelectric Effects in Engineered Multiferroic Heterostructures

Full voltage manipulation of the resistance of a magnetic tunnel junction

Shear-strain-mediated magnetoelectric effects revealed by imaging

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