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101. Ultrafast terahertz field control of electronic and structural interactions in vanadium dioxide

Author

Gray, A. X., Hoffmann, M. C., Jeong, J., Aetukuri, N. P., Zhu, D., Hwang, H. Y., Brandt, N. C., Wen, H., Sternbach, A. J., Bonetti, S., Reid, A. H., Kukreja, R., Graves, C., Wang, T., Granitzka, P., Chen, Z., Higley, D. J., Chase, T., Jal, E., Abreu, E., Liu, M. K., Weng, T-C, Sokaras, D., Nordlund, D., Chollet, M., Alonso-Mori, R., Lemke, H., Glownia, J. M., Trigo, M., Zhu, Y., Ohldag, H., Freeland, J. W., Samant, M. G., Berakdar, J., Averitt, R. D., Nelson, K. A., Parkin, S. S. P., Dürr, Hermann, Gray, A. X., Hoffmann, M. C., Jeong, J., Aetukuri, N. P., Zhu, D., Hwang, H. Y., Brandt, N. C., Wen, H., Sternbach, A. J., Bonetti, S., Reid, A. H., Kukreja, R., Graves, C., Wang, T., Granitzka, P., Chen, Z., Higley, D. J., Chase, T., Jal, E., Abreu, E., Liu, M. K., Weng, T-C, Sokaras, D., Nordlund, D., Chollet, M., Alonso-Mori, R., Lemke, H., Glownia, J. M., Trigo, M., Zhu, Y., Ohldag, H., Freeland, J. W., Samant, M. G., Berakdar, J., Averitt, R. D., Nelson, K. A., Parkin, S. S. P., and Dürr, Hermann

Abstract

Vanadium dioxide (VO2), an archetypal correlated-electron material, undergoes an insulator-metal transition near room temperature that exhibits electron-correlation-driven and structurally driven physics. Using ultrafast temperature- and fluence-dependent optical spectroscopy and x-ray scattering, we show that multiple interrelated electronic and structural processes in the nonequilibrium dynamics in VO2 can be disentangled in the time domain. Specifically, following intense subpicosecond terahertz (THz) electric-field excitation, a partial collapse of the insulating gap occurs within the first picosecond. At temperatures sufficiently close to the transition temperature and for THz peak fields above a threshold of approximately 1 MV/cm, this electronic reconfiguration initiates a change in lattice symmetry taking place on a slower timescale. We identify the kinetic energy increase of electrons tunneling in the strong electric field as the driving force, illustrating a promising method to control electronic and structural interactions in correlated materials on an ultrafast timescale.

Published
2018
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102. Ultrafast terahertz field control of electronic and structural interactions in vanadium dioxide

Author

Massachusetts Institute of Technology. Department of Chemistry, Hwang, Harold Y., Brandt, Nathaniel Curran, Nelson, Keith Adam, Gray, A. X., Hoffmann, M. C., Jeong, J., Aetukuri, N. P., Zhu, D., Wen, H., Sternbach, A. J., Bonetti, S., Reid, A. H., Kukreja, R., Graves, C., Wang, T., Granitzka, P., Chen, Z., Higley, D. J., Chase, T., Jal, E., Abreu, E., Liu, M. K., Weng, T.-C., Sokaras, D., Nordlund, D., Chollet, M., Alonso-Mori, R., Lemke, H., Glownia, J. M., Trigo, M., Zhu, Y., Ohldag, H., Freeland, J. W., Samant, M. G., Berakdar, J., Averitt, R. D., Parkin, S. S. P., Dürr, H. A., Massachusetts Institute of Technology. Department of Chemistry, Hwang, Harold Y., Brandt, Nathaniel Curran, Nelson, Keith Adam, Gray, A. X., Hoffmann, M. C., Jeong, J., Aetukuri, N. P., Zhu, D., Wen, H., Sternbach, A. J., Bonetti, S., Reid, A. H., Kukreja, R., Graves, C., Wang, T., Granitzka, P., Chen, Z., Higley, D. J., Chase, T., Jal, E., Abreu, E., Liu, M. K., Weng, T.-C., Sokaras, D., Nordlund, D., Chollet, M., Alonso-Mori, R., Lemke, H., Glownia, J. M., Trigo, M., Zhu, Y., Ohldag, H., Freeland, J. W., Samant, M. G., Berakdar, J., Averitt, R. D., Parkin, S. S. P., and Dürr, H. A.

Abstract

Vanadium dioxide (VO₂), an archetypal correlated-electron material, undergoes an insulator-metal transition near room temperature that exhibits electron-correlation-driven and structurally driven physics. Using ultrafast temperature- and fluence-dependent optical spectroscopy and x-ray scattering, we show that multiple interrelated electronic and structural processes in the nonequilibrium dynamics in VO₂ can be disentangled in the time domain. Specifically, following intense subpicosecond terahertz (THz) electric-field excitation, a partial collapse of the insulating gap occurs within the first picosecond. At temperatures sufficiently close to the transition temperature and for THz peak fields above a threshold of approximately 1 MV/cm, this electronic reconfiguration initiates a change in lattice symmetry taking place on a slower timescale. We identify the kinetic energy increase of electrons tunneling in the strong electric field as the driving force, illustrating a promising method to control electronic and structural interactions in correlated materials on an ultrafast timescale., United States. Office of Naval Research (Grant N00014-13-1-0509), National Science Foundation (U.S.) (Grant CHE-1111557)

Published
2018

103. Reply to “Comment on ‘Ultrafast terahertz-field-driven ionic response in ferroelectric

Author

Massachusetts Institute of Technology. Department of Chemistry, Hwang, H. Y., Brandt, Nathaniel Curran, Lu, Jian, Nelson, Keith Adam, Chen, F., Zhu, Y., Liu, S., Qi, Y., Quirin, F., Enquist, H., Zalden, P., Hu, T., Goodfellow, J., Sher, M.-J., Hoffmann, M. C., Zhu, D., Lemke, H., Glownia, J., Chollet, M., Damodaran, A. R., Park, J., Cai, Z., Jung, I. W., Highland, M. J., Walko, D. A., Freeland, J. W., Evans, P. G., Vailionis, A., Larsson, J., Rappe, A. M., Sokolowski-Tinten, K., Martin, L. W., Wen, H., Lindenberg, A. M., Massachusetts Institute of Technology. Department of Chemistry, Hwang, H. Y., Brandt, Nathaniel Curran, Lu, Jian, Nelson, Keith Adam, Chen, F., Zhu, Y., Liu, S., Qi, Y., Quirin, F., Enquist, H., Zalden, P., Hu, T., Goodfellow, J., Sher, M.-J., Hoffmann, M. C., Zhu, D., Lemke, H., Glownia, J., Chollet, M., Damodaran, A. R., Park, J., Cai, Z., Jung, I. W., Highland, M. J., Walko, D. A., Freeland, J. W., Evans, P. G., Vailionis, A., Larsson, J., Rappe, A. M., Sokolowski-Tinten, K., Martin, L. W., Wen, H., and Lindenberg, A. M.

Abstract

In this reply to S. Durbin's comment on our original paper “Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO₃,” we concur that his final equations 8 and 9 more accurately describe the change in diffracted intensity as a function of Ti displacement. We also provide an alternative derivation based on an ensemble average over unit cells. The conclusions of the paper are unaffected by this correction.

Published
2018

106. Ultrafast terahertz field control of electronic and structural interactions in vanadium dioxide

Author

Gray, A. X., primary, Hoffmann, M. C., additional, Jeong, J., additional, Aetukuri, N. P., additional, Zhu, D., additional, Hwang, H. Y., additional, Brandt, N. C., additional, Wen, H., additional, Sternbach, A. J., additional, Bonetti, S., additional, Reid, A. H., additional, Kukreja, R., additional, Graves, C., additional, Wang, T., additional, Granitzka, P., additional, Chen, Z., additional, Higley, D. J., additional, Chase, T., additional, Jal, E., additional, Abreu, E., additional, Liu, M. K., additional, Weng, T.-C., additional, Sokaras, D., additional, Nordlund, D., additional, Chollet, M., additional, Alonso-Mori, R., additional, Lemke, H., additional, Glownia, J. M., additional, Trigo, M., additional, Zhu, Y., additional, Ohldag, H., additional, Freeland, J. W., additional, Samant, M. G., additional, Berakdar, J., additional, Averitt, R. D., additional, Nelson, K. A., additional, Parkin, S. S. P., additional, and Dürr, H. A., additional

Published
2018
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107. Reply to “Comment on ‘Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO3 ' ”

Author

Chen, F., primary, Zhu, Y., additional, Liu, S., additional, Qi, Y., additional, Hwang, H. Y., additional, Brandt, N. C., additional, Lu, J., additional, Quirin, F., additional, Enquist, H., additional, Zalden, P., additional, Hu, T., additional, Goodfellow, J., additional, Sher, M.-J., additional, Hoffmann, M. C., additional, Zhu, D., additional, Lemke, H., additional, Glownia, J., additional, Chollet, M., additional, Damodaran, A. R., additional, Park, J., additional, Cai, Z., additional, Jung, I. W., additional, Highland, M. J., additional, Walko, D. A., additional, Freeland, J. W., additional, Evans, P. G., additional, Vailionis, A., additional, Larsson, J., additional, Nelson, K. A., additional, Rappe, A. M., additional, Sokolowski-Tinten, K., additional, Martin, L. W., additional, Wen, H., additional, and Lindenberg, A. M., additional

Published
2018
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109. Interphase exchange coupling in Fe/Sm–Co bilayers with gradient Fe thickness.

Author

Ming-hui Yu, Hattrick-Simpers, Jason, Takeuchi, Ichiro, Jing Li, Wang, Z. L., Liu, J. P., Lofland, S. E., Tyagi, Somdev, Freeland, J. W., Giubertoni, D., Bersani, M., and Anderle, M.

Subjects
MAGNETIC coupling, MAGNETISM, MAGNETIC circular dichroism, ELECTROMAGNETIC induction, MAGNETOOPTICS, HYSTERESIS, RESEARCH
Abstract

We have fabricated Fe/Sm–Co bilayers with gradient Fe thicknesses in order to systematically study the dependence of exchange coupling on the thickness of the Fe layer. The Fe layer was deposited at two different temperatures (150 and 300 °C) to study the effect of deposition temperature on the exchange coupling. Magneto-optical Kerr effect and x-ray magnetic circular dichroism (XMCD) have been employed as nondestructive rapid characterization tools to map the magnetic properties of the gradient samples. Systematic enhancement in exchange coupling between the soft layer and the hard layer is observed as the soft layer thickness is decreased. Separate exchange couplings of the Fe layer with Co and Sm in the hard layer are revealed through measuring the element-specific hysteresis curves using XMCD. The single-phase-like magnetization reversal critical thickness increases from 12 nm for Fe deposited at 150 °C to 24 nm for Fe deposited at 300 °C, indicating an important role of the state of the interface in the exchange coupling. [ABSTRACT FROM AUTHOR]

Published
2005
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110. Thermal effect on the oxides on Nb(100) studied by synchrotron-radiation x-ray photoelectron spectroscopy.

Author

Ma, Qing, Ryan, P., Freeland, J. W., and Rosenberg, R. A.

Subjects
OXIDES, SEMICONDUCTOR doping, ELECTRON emission, PHOTOELECTRON spectroscopy, MOLECULAR orbitals, SOLUTION (Chemistry), RADIATION
Abstract

Synchrotron-radiation glancing-incidence and angle-resolved photoelectron spectroscopy (PES) is used to study the oxides grown in air on a single-crystal Nb(100) surface. Both core-level and valance-band PES are measured for various heat treatments. Glancing-incidence excitation was used to characterize the outer 2-nm Nb2O5 layer without influence from the substrate and to profile through various oxides by varying the incidence angle. Immediately adjacent to this amorphous layer is a layer of NbO2, which contributes to the density of states at 1.2 eV below the Fermi level. Thereafter, there exist other oxides that interface with the metal substrate. Annealing at 430 K induces a “mild” chemical reaction, which is contained essentially in the oxide layer. Annealing at 550 K causes oxygen diffusion into the metal and leaves an oxide layer consisting primarily of Nb2O and a roughened surface, as evidenced by angle-resolved photoemission measurements. Oxide composition alteration caused by annealing at these moderated temperatures is believed to be interface mediated. [ABSTRACT FROM AUTHOR]

Published
2004
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111. Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO[subscript 3]

Author

Massachusetts Institute of Technology. Department of Chemistry, Hwang, Harold Y., Brandt, Nathaniel Curran, Lu, J., Nelson, Keith Adam, Chen, F., Zhu, Y., Liu, S., Qi, Y., Quirin, F., Enquist, H., Zalden, P., Hu, T., Goodfellow, J., Sher, M.-J., Hoffmann, M. C., Zhu, D., Lemke, H., Glownia, J., Chollet, M., Damodaran, A. R., Park, J., Cai, Z., Jung, I. W., Highland, M. J., Walko, D. A., Freeland, J. W., Evans, P. G., Vailionis, A., Larsson, J., Rappe, A. M., Sokolowski-Tinten, K., Martin, L. W., Wen, H., Lindenberg, A. M., Massachusetts Institute of Technology. Department of Chemistry, Hwang, Harold Y., Brandt, Nathaniel Curran, Lu, J., Nelson, Keith Adam, Chen, F., Zhu, Y., Liu, S., Qi, Y., Quirin, F., Enquist, H., Zalden, P., Hu, T., Goodfellow, J., Sher, M.-J., Hoffmann, M. C., Zhu, D., Lemke, H., Glownia, J., Chollet, M., Damodaran, A. R., Park, J., Cai, Z., Jung, I. W., Highland, M. J., Walko, D. A., Freeland, J. W., Evans, P. G., Vailionis, A., Larsson, J., Rappe, A. M., Sokolowski-Tinten, K., Martin, L. W., Wen, H., and Lindenberg, A. M.

Abstract

The dynamical processes associated with electric field manipulation of the polarization in a ferroelectric remain largely unknown but fundamentally determine the speed and functionality of ferroelectric materials and devices. Here we apply subpicosecond duration, single-cycle terahertz pulses as an ultrafast electric field bias to prototypical BaTiO[subscript 3] ferroelectric thin films with the atomic-scale response probed by femtosecond x-ray-scattering techniques. We show that electric fields applied perpendicular to the ferroelectric polarization drive large-amplitude displacements of the titanium atoms along the ferroelectric polarization axis, comparable to that of the built-in displacements associated with the intrinsic polarization and incoherent across unit cells. This effect is associated with a dynamic rotation of the ferroelectric polarization switching on and then off on picosecond time scales. These transient polarization modulations are followed by long-lived vibrational heating effects driven by resonant excitation of the ferroelectric soft mode, as reflected in changes in the c-axis tetragonality. The ultrafast structural characterization described here enables a direct comparison with first-principles-based molecular-dynamics simulations, with good agreement obtained.

Published
2017

112. Deterministic and robust room-temperature exchange coupling in monodomain multiferroic BiFeO3 heterostructures

Author

Saenrang, W., primary, Davidson, B. A., additional, Maccherozzi, F., additional, Podkaminer, J. P., additional, Irwin, J., additional, Johnson, R. D., additional, Freeland, J. W., additional, Íñiguez, J., additional, Schad, J. L., additional, Reierson, K., additional, Frederick, J. C., additional, Vaz, C. A. F., additional, Howald, L., additional, Kim, T. H., additional, Ryu, S., additional, Veenendaal, M. v., additional, Radaelli, P. G., additional, Dhesi, S. S., additional, Rzchowski, M. S., additional, and Eom, C. B., additional

Published
2017
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116. Voltage-controlled interlayer coupling in perpendicularly magnetized magnetic tunnel junctions

Author

Newhouse-Illige, T., primary, Liu, Yaohua, additional, Xu, M., additional, Reifsnyder Hickey, D., additional, Kundu, A., additional, Almasi, H., additional, Bi, Chong, additional, Wang, X., additional, Freeland, J. W., additional, Keavney, D. J., additional, Sun, C. J., additional, Xu, Y. H., additional, Rosales, M., additional, Cheng, X. M., additional, Zhang, Shufeng, additional, Mkhoyan, K. A., additional, and Wang, W. G., additional

Published
2017
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117. Symmetrical interfacial reconstruction and magnetism in La0.7Ca0.3MnO3/YBa2Cu3O7/La0.7Ca0.3MnO3heterostructures

Author

Visani, C., Tornos, J., Nemes, N. M., Leon, C., Santamaria, J., te Velthuis, S. G. E., Liu, Yaohua, Hoffmann, A., Freeland, J. W., Garcia Hernandez, M., Fitzsimmons, M. R., Kirby, B. J., Varela, M., Pennycook, S. J., ROCCI, MIRKO, Visani, C., Tornos, J., Nemes, N. M., Rocci, Mirko, Leon, C., Santamaria, J., te Velthuis, S. G. E., Liu, Yaohua, Hoffmann, A., Freeland, J. W., Garcia Hernandez, M., Fitzsimmons, M. R., Kirby, B. J., Varela, M., and Pennycook, S. J.

Published
2011

118. Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO3

Author

Chen, F., primary, Zhu, Y., additional, Liu, S., additional, Qi, Y., additional, Hwang, H. Y., additional, Brandt, N. C., additional, Lu, J., additional, Quirin, F., additional, Enquist, H., additional, Zalden, P., additional, Hu, T., additional, Goodfellow, J., additional, Sher, M.-J., additional, Hoffmann, M. C., additional, Zhu, D., additional, Lemke, H., additional, Glownia, J., additional, Chollet, M., additional, Damodaran, A. R., additional, Park, J., additional, Cai, Z., additional, Jung, I. W., additional, Highland, M. J., additional, Walko, D. A., additional, Freeland, J. W., additional, Evans, P. G., additional, Vailionis, A., additional, Larsson, J., additional, Nelson, K. A., additional, Rappe, A. M., additional, Sokolowski-Tinten, K., additional, Martin, L. W., additional, Wen, H., additional, and Lindenberg, A. M., additional

Published
2016
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121. Superconductor to Mott insulator transition in YBa2Cu3O7/LaCaMnO3 heterostructures

Author

Gray, B. A., primary, Middey, S., additional, Conti, G., additional, Gray, A. X., additional, Kuo, C.-T., additional, Kaiser, A. M., additional, Ueda, S., additional, Kobayashi, K., additional, Meyers, D., additional, Kareev, M., additional, Tung, I. C., additional, Liu, Jian, additional, Fadley, C. S., additional, Chakhalian, J., additional, and Freeland, J. W., additional

Published
2016
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126. Magnetic Interactions at the Nanoscale in Trilayer Titanates

Author

Cao, Yanwei, primary, Yang, Zhenzhong, additional, Kareev, M., additional, Liu, Xiaoran, additional, Meyers, D., additional, Middey, S., additional, Choudhury, D., additional, Shafer, P., additional, Guo, Jiandong, additional, Freeland, J. W., additional, Arenholz, E., additional, Gu, Lin, additional, and Chakhalian, J., additional

Published
2016
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129. Lateral- and layer-resolved magnetization reversals in a spin-valve array.

Author

Lee, D. R., Choi, Y., Freeland, J. W., Keavney, D. J., Srajer, G., Metlushko, V., and Ilic, B.

Abstract

Using element-sensitive x-ray resonant magnetic scattering, layer-resolved magnetic hysteresis loops were measured on a periodic square frame nanostrucutre. Taking advantage of the lateral periodicity, we measured hysteresis loops at several x-ray diffraction orders to extract hysteresis loops from different regions of the square frame structures. The layer- and spatially resolved magnetic measurements revealed distinct magnetic reversal mechanisms in different regions due to interplay between the shape anisotropy and interlayer dipolar coupling. The assumed vortex state during the reversal in our analysis was confirmed by photoemission electron microscopy imaging. [ABSTRACT FROM AUTHOR]

Published
2008
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130. Domain-specific magnetization reversals on a Permalloy square ring array.

Author

Lee, D. R., Freeland, J. W., Srajer, G., Metlushko, V., and Chun-Yeol You

Subjects
*MAGNETIZATION, *MAGNETIC materials, *HYSTERESIS, *SIMULATION methods & models, *PHYSICS
Abstract

We present domain-specific magnetization reversals extracted from soft x-ray resonant magnetic scattering measurements on a Permalloy square ring array. The extracted domain-specific hysteresis loops reveal that the magnetization of the domain parallel to the field is strongly pinned, while those of other domains rotate continuously. In comparison with the micromagnetic simulation, the hysteresis loop on the pinned domain indicates a possibility of the coexistence of the square rings with the vortex and onion states. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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135. Reversible electric-field control of magnetization at oxide interfaces

Author

Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Research Council, Department of Energy (US), Cuellar, Fabián A., Liu, Y. H., Salafranca, J., Nemes, N. M., Iborra, E., Sanchez-Santolino, Gabriel, Varela, M., García-Hernández, Mar, Freeland, J. W., Zhernenkov, M., Fitzsimmons, M. R., Okamoto, S., Pennycook, Stephen J., Bibes, M., Barthélémy, A., Te Velthuis, S. G. E., Sefrioui, Z., Leon, C., Santamaría, Jacobo, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Research Council, Department of Energy (US), Cuellar, Fabián A., Liu, Y. H., Salafranca, J., Nemes, N. M., Iborra, E., Sanchez-Santolino, Gabriel, Varela, M., García-Hernández, Mar, Freeland, J. W., Zhernenkov, M., Fitzsimmons, M. R., Okamoto, S., Pennycook, Stephen J., Bibes, M., Barthélémy, A., Te Velthuis, S. G. E., Sefrioui, Z., Leon, C., and Santamaría, Jacobo

Abstract

Electric-field control of magnetism has remained a major challenge which would greatly impact data storage technology. Although progress in this direction has been recently achieved, reversible magnetization switching by an electric field requires the assistance of a bias magnetic field. Here we take advantage of the novel electronic phenomena emerging at interfaces between correlated oxides and demonstrate reversible, voltage' driven magnetization switching without magnetic field. Sandwiching a non-superconducting cuprate between two manganese oxide layers, we find a novel form of magnetoelectric coupling arising from the orbital reconstruction at the interface between interfacial Mn spins and localized states in the CuO 2 planes. This results in a ferromagnetic coupling between the manganite layers that can be controlled by a voltage. Consequently, magnetic tunnel junctions can be electrically toggled between two magnetization states, and the corresponding spin' dependent resistance states, in the absence of a magnetic field.

Published
2014

136. Transient electronic structure of the photoinduced phase of $\mathrm{Pr_{0.7} Ca _{0.3} MnO_3}$ probed with soft x-ray pulses

Author

Rini, M., Zhu, Y., Schoenlein, R. W., Wall, S., Tobey, R. I., Ehrke, H., Garl, T., Freeland, J. W., Tomioka, Y., Tokura, Y., and Cavalleri, A.

Subjects
Condensed Matter::Materials Science, Condensed Matter::Strongly Correlated Electrons, ddc:530
Abstract

We use time-resolved x-ray absorption near-edge structure spectroscopy to investigate the electronic dynamics associated with the photoinduced insulator-to-metal phase transition in the colossal magnetoresistive manganite Pr0.7Ca0.3MnO3. Absorption changes at the O K and Mn L edges directly monitor the evolution of the density of unoccupied states in the transient photoinduced phase. We show that the electronic structure of the photoinduced phase is remarkably similar to that of the ferromagnetic metallic phase reached in related manganites upon cooling below the Curie temperature

Published
2009
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137. Deterministic and robust room-temperature exchange coupling in monodomain multiferroic BiFeO3 heterostructures.

Author

Saenrang, W., Davidson, B. A., Maccherozzi, F., Podkaminer, J. P., Irwin, J., Johnson, R. D., Freeland, J. W., Íñiguez, J., Schad, J. L., Reierson, K., Frederick, J. C., Vaz, C. A. F., Howald, L., Kim, T. H., Ryu, S., Veenendaal, M. v., Radaelli, P. G., Dhesi, S. S., Rzchowski, M. S., and Eom, C. B.

Subjects
THIN film devices, HETEROSTRUCTURES, DOMAIN walls (String models)
Abstract

Exploiting multiferroic BiFeO3 thin films in spintronic devices requires deterministic and robust control of both internal magnetoelectric coupling in BiFeO3, as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. Previous reports utilized approaches based on multi-step ferroelectric switching with multiple ferroelectric domains. Because domain walls can be responsible for fatigue, contain localized charges intrinsically or via defects, and present problems for device reproducibility and scaling, an alternative approach using a monodomain magnetoelectric state with single-step switching is desirable. Here we demonstrate room temperature, deterministic and robust, exchange coupling between monodomain BiFeO3 films and Co overlayer that is intrinsic (i.e., not dependent on domain walls). Direct coupling between BiFeO3 antiferromagnetic order and Co magnetization is observed, with ~ 90° in-plane Co moment rotation upon single-step switching that is reproducible for hundreds of cycles. This has important consequences for practical, low power non-volatile magnetoelectric devices utilizing BiFeO3. [ABSTRACT FROM AUTHOR]

Published
2017
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138. Oscillatory interlayer coupling through (111) oriented noble metal spacers.

Author

Keavney, D. J., Storm, D. F., Freeland, J. W., Walker, J. C., Pini, M. G., Politi, P., and Rettori, A.

Subjects
SPIN waves, PRECIOUS metals, MOSSBAUER spectroscopy
Abstract

Provides information on a study that examined the spin-wave spectrum of multilayer structures Fe(110)/Nm(111), with different thicknesses of the noble metal interlayer using a surface-sensitive M ö ssbauer spectroscopy technique.

Published
1994
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140. Competition between heavy fermion and Kondo interaction in isoelectronic A-site-ordered perovskites

Author

Meyers, D., primary, Middey, S., additional, Cheng, J.-G., additional, Mukherjee, Swarnakamal, additional, Gray, B. A., additional, Cao, Yanwei, additional, Zhou, J.-S., additional, Goodenough, J.B., additional, Choi, Yongseong, additional, Haskel, D., additional, Freeland, J. W., additional, Saha-Dasgupta, T., additional, and Chakhalian, J., additional

Published
2014
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144. Dynamic layer rearrangement during growth of layered oxide films by molecular beam epitaxy

Author

Lee, J. H., primary, Luo, G., additional, Tung, I. C., additional, Chang, S. H., additional, Luo, Z., additional, Malshe, M., additional, Gadre, M., additional, Bhattacharya, A., additional, Nakhmanson, S. M., additional, Eastman, J. A., additional, Hong, H., additional, Jellinek, J., additional, Morgan, D., additional, Fong, D. D., additional, and Freeland, J. W., additional

Published
2014
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147. Reversible electric-field control of magnetization at oxide interfaces

Author

Cuellar, F. A., primary, Liu, Y. H., additional, Salafranca, J., additional, Nemes, N., additional, Iborra, E., additional, Sanchez-Santolino, G., additional, Varela, M., additional, Hernandez, M. Garcia, additional, Freeland, J. W., additional, Zhernenkov, M., additional, Fitzsimmons, M. R., additional, Okamoto, S., additional, Pennycook, S. J., additional, Bibes, M., additional, Barthélémy, A., additional, te Velthuis, S.G.E., additional, Sefrioui, Z., additional, Leon, C., additional, and Santamaria, J., additional

Published
2014
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150. Asymmetric Orbital-Lattice Interactions in Ultrathin Correlated Oxide Films

Author

Chakhalian, J., Rondinelli, J. M., Liu, Jian, Gray, B. A., Kareev, M., Moon, E. J., Prasai, N., Cohn, J. L., Varela, M., Tung, I. C., Bedzyk, M. J., Altendorf, S. G., Strigari, F., Dabrowski, B., Tjeng, L. H., Ryan, P. J., Freeland, J. W., Chakhalian, J., Rondinelli, J. M., Liu, Jian, Gray, B. A., Kareev, M., Moon, E. J., Prasai, N., Cohn, J. L., Varela, M., Tung, I. C., Bedzyk, M. J., Altendorf, S. G., Strigari, F., Dabrowski, B., Tjeng, L. H., Ryan, P. J., and Freeland, J. W.

Abstract

Using resonant x-ray spectroscopies combined with density functional calculations, we find an asymmetric biaxial strain-induced d-orbital response in ultrathin films of the correlated metal LaNiO3 which are not accessible in the bulk. The sign of the misfit strain governs the stability of an octahedral breathing distortion, which, in turn, produces an emergent charge-ordered ground state with an altered ligand-hole density and bond covalency. Control of this new mechanism opens a pathway to rational orbital engineering, providing a platform for artificially designed Mott materials.

Published
2011

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