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268 results on '"Íñiguez, J."'

1. Influence of ferroelastic domain walls on thermal conductivity

Author

Limelette, P., Kamily, M. El, Aramberri, H., Giovannelli, F., Royo, M., Rurali, R., Monot-Laffez, I., Íñiguez, J., and Nataf, G. F.

Subjects
Condensed Matter - Materials Science
Abstract

Enabling on-demand control of heat flow is key for the development of next-generation electronic devices, solid-state heat pumps, and thermal logic. However, precise and agile tuning of the relevant microscopic material parameters for adjusting thermal conductivities remains elusive. Here, we study several single crystals of lanthanum aluminate (LaAlO$_{3}$) with different domain structures and show that ferroelastic domain walls behave as boundaries that act like efficient controllers to govern thermal conductivity. At low temperature (3 K), we demonstrate a fivefold reduction in thermal conductivity induced by domain walls orthogonal to the heat flow and a twofold reduction when they are parallel to the heat flow. Atomistic calculations fully support this experimental observation. By breaking down phonon scattering mechanisms, we also analyze the temperature dependence of the thermal conductivity to derive a quantitative relation between thermal conductivity variations and domain wall organization and density.

Published
2023
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2. Transferring orbital angular momentum to an electron beam reveals toroidal and chiral order

Author

Nguyen, KX, Jiang, Y, Cao, MC, Purohit, P, Yadav, AK, García-Fernández, P, Tate, MW, Chang, CS, Aguado-Puente, P, Íñiguez, J, Gomez-Ortiz, F, Gruner, SM, Junquera, J, Martin, LW, Ramesh, R, and Muller, DA

Subjects
Physical Sciences, Chemical Sciences, Engineering, Fluids & Plasmas
Abstract

Orbital angular momentum (OAM) and torque transfer play central roles in a wide range of magnetic textures and devices including skyrmions and spin-torque electronics. Analogous topological structures are now also being explored in ferroelectrics, including polarization vortex arrays in ferroelectric/dielectric superlattices. Unlike magnetic toroidal order, electric toroidal order does not couple directly to linear external fields. Instead, we find that the presence of an electric toroidal moment in a ferrorotational phase transfers measurable torque and OAM to a localized electron beam in the ballistic limit. We record these torque transfers from a high-energy electron beam using a momentum-resolved detector. This approach provides a high-sensitivity method to detect polarization fields and their more complex order parameters and topologies. In addition to toroidal order, we also demonstrate high-precision measurements of vorticity and chirality for polar vortexlike phases.

Published
2023

4. Ferroelectricity in epitaxially strained rhombohedral ZrO2 thin films

Author

Silva, J. P. B., Negrea, R. F., Istrate, M. C., Dutta, S., Aramberri, H., Íñiguez, J., Figueiras, F. G., Ghica, C., Sekhar, K. C., and Kholkin, A. L.

Subjects
Condensed Matter - Materials Science
Abstract

Zirconia and hafnia based thin films have attracted tremendous attention in the last decade due to their unexpected ferroelectric behavior at the nanoscale, which facilitates the downscaling of ferroelectric devices. The present work reports a novel ferroelectric rhombohedral phase of ZrO2 that can be achieved in thin films grown on (111)- Nb:SrTiO3 substrates by ion-beam sputtering. Structural and ferroelectric characterizations reveal that the (111)-oriented ZrO2 films are under epitaxial compressive strain and display a switchable ferroelectric polarization of about 20.2 {\mu}C/cm2 with a coercive field of 1.5 MV/cm. Moreover, the time dependent polarization reversal characteristics of Nb:STO/ZrO2/Au film capacitors exhibit bell-shape curves, a typical feature of ferroelectric films associated with domains reversal. The estimated activation field is comparable to the coercive field obtained from polarization-electric field hysteresis loops. Interestingly, the studied films show ferroelectric behavior per se, i.e., there is no need to apply the wake-up cycle that is essential to induce ferroelectricity in the conventional (orthorhombic) ferroelectric phase of ZrO2. Therefore, the present films have a technologically advantage over the previously studied ferroelectric ZrO2 films, and may be attractive for nanoscale ferroelectric devices., Comment: 26 pages, 9 figures

Published
2020
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5. Local negative permittivity and topological phase transition in polar skyrmions

Author

Das, S, Hong, Z, Stoica, VA, Gonçalves, MAP, Shao, YT, Parsonnet, E, Marksz, EJ, Saremi, S, McCarter, MR, Reynoso, A, Long, CJ, Hagerstrom, AM, Meyers, D, Ravi, V, Prasad, B, Zhou, H, Zhang, Z, Wen, H, Gómez-Ortiz, F, García-Fernández, P, Bokor, J, Íñiguez, J, Freeland, JW, Orloff, ND, Junquera, J, Chen, LQ, Salahuddin, S, Muller, DA, Martin, LW, and Ramesh, R

Subjects
Nanoscience & Nanotechnology
Abstract

Topological solitons such as magnetic skyrmions have drawn attention as stable quasi-particle-like objects. The recent discovery of polar vortices and skyrmions in ferroelectric oxide superlattices has opened up new vistas to explore topology, emergent phenomena and approaches for manipulating such features with electric fields. Using macroscopic dielectric measurements, coupled with direct scanning convergent beam electron diffraction imaging on the atomic scale, theoretical phase-field simulations and second-principles calculations, we demonstrate that polar skyrmions in (PbTiO3)n/(SrTiO3)n superlattices are distinguished by a sheath of negative permittivity at the periphery of each skyrmion. This enhances the effective dielectric permittivity compared with the individual SrTiO3 and PbTiO3 layers. Moreover, the response of these topologically protected structures to electric field and temperature shows a reversible phase transition from the skyrmion state to a trivial uniform ferroelectric state, accompanied by large tunability of the dielectric permittivity. Pulsed switching measurements show a time-dependent evolution and recovery of the skyrmion state (and macroscopic dielectric response). The interrelationship between topological and dielectric properties presents an opportunity to simultaneously manipulate both by a single, and easily controlled, stimulus, the applied electric field.

Published
2021

6. Observation of room-temperature polar skyrmions.

Author

Das, S, Tang, YL, Hong, Z, Gonçalves, MAP, McCarter, MR, Klewe, C, Nguyen, KX, Gómez-Ortiz, F, Shafer, P, Arenholz, E, Stoica, VA, Hsu, S-L, Wang, B, Ophus, C, Liu, JF, Nelson, CT, Saremi, S, Prasad, B, Mei, AB, Schlom, DG, Íñiguez, J, García-Fernández, P, Muller, DA, Chen, LQ, Junquera, J, Martin, LW, and Ramesh, R

Subjects
MD Multidisciplinary, General Science & Technology
Abstract

Complex topological configurations are fertile ground for exploring emergent phenomena and exotic phases in condensed-matter physics. For example, the recent discovery of polarization vortices and their associated complex-phase coexistence and response under applied electric fields in superlattices of (PbTiO3)n/(SrTiO3)n suggests the presence of a complex, multi-dimensional system capable of interesting physical responses, such as chirality, negative capacitance and large piezo-electric responses1-3. Here, by varying epitaxial constraints, we discover room-temperature polar-skyrmion bubbles in a lead titanate layer confined by strontium titanate layers, which are imaged by atomic-resolution scanning transmission electron microscopy. Phase-field modelling and second-principles calculations reveal that the polar-skyrmion bubbles have a skyrmion number of +1, and resonant soft-X-ray diffraction experiments show circular dichroism, confirming chirality. Such nanometre-scale polar-skyrmion bubbles are the electric analogues of magnetic skyrmions, and could contribute to the advancement of ferroelectrics towards functionalities incorporating emergent chirality and electrically controllable negative capacitance.

Published
2019

7. Electrocaloric effects in the lead-free Ba(Zr,Ti)O$_{3}$ relaxor ferroelectric from atomistic simulations

Author

Jiang, Zhijun, Prokhorenko, Sergei, Prosandeev, Sergey, Nahas, Y., Wang, D., Íñiguez, J., Defay, E., and Bellaiche, L.

Subjects
Condensed Matter - Materials Science
Abstract

Atomistic effective Hamiltonian simulations are used to investigate electrocaloric (EC) effects in the lead-free Ba(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ (BZT) relaxor ferroelectric. We find that the EC coefficient varies non-monotonically with the field at any temperature, presenting a maximum that can be traced back to the behavior of BZT's polar nanoregions. We also introduce a simple Landau-based model that reproduces the EC behavior of BZT as a function of field and temperature, and which is directly applicable to other compounds. Finally, we confirm that, for low temperatures (i.e., in non-ergodic conditions), the usual indirect approach to measure the EC response provides an estimate that differs quantitatively from a direct evaluation of the field-induced temperature change., Comment: 9 pages, 4 figures

Published
2017
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9. Multiple strain-induced phase transitions in LaNiO3 thin films

Author

Weber, M. C., Guennou, M., Dix, N., Pesquera, D., Sánchez, F., Herranz, G., Fontcuberta, J., López-Conesa, L., Estradé, S., Peiró, F., Iñiguez, J., and Kreisel, J.

Subjects
Condensed Matter - Materials Science
Abstract

Strain effects on epitaxial thin films of LaNiO3 grown on different single crystalline substrates are studied by Raman scattering and first-principles simulation. New Raman modes, not present in bulk or fully-relaxed films, appear under both compressive and tensile strains, indicating symmetry reductions. Interestingly, the Raman spectra and the underlying crystal symmetry for tensile and compressively strained films are different. Extensive mapping of LaNiO3 phase stability is addressed by simulations, showing that a variety of crystalline phases are indeed stabilized under strain which may impact the electronic orbital hierarchy. The calculated Raman frequencies reproduce the principal features of the experimental spectra, supporting the validity of the multiple strain-driven structural transitions predicted by the simulations., Comment: 18 pages, 7 figures

Published
2016
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11. Phase coexistence and electric-field control of toroidal order in oxide superlattices

Author

Damodaran, AR, Clarkson, JD, Hong, Z, Liu, H, Yadav, AK, Nelson, CT, Hsu, S-L, McCarter, MR, Park, K-D, Kravtsov, V, Farhan, A, Dong, Y, Cai, Z, Zhou, H, Aguado-Puente, P, García-Fernández, P, Íñiguez, J, Junquera, J, Scholl, A, Raschke, MB, Chen, L-Q, Fong, DD, Ramesh, R, and Martin, LW

Subjects
Engineering, Materials Engineering, Physical Sciences, Condensed Matter Physics, Affordable and Clean Energy, Nanoscience & Nanotechnology
Abstract

Systems that exhibit phase competition, order parameter coexistence, and emergent order parameter topologies constitute a major part of modern condensed-matter physics. Here, by applying a range of characterization techniques, and simulations, we observe that in PbTiO3/SrTiO3 superlattices all of these effects can be found. By exploring superlattice period-, temperature- and field-dependent evolution of these structures, we observe several new features. First, it is possible to engineer phase coexistence mediated by a first-order phase transition between an emergent, low-temperature vortex phase with electric toroidal order and a high-temperature ferroelectric a1/a2 phase. At room temperature, the coexisting vortex and ferroelectric phases form a mesoscale, fibre-textured hierarchical superstructure. The vortex phase possesses an axial polarization, set by the net polarization of the surrounding ferroelectric domains, such that it possesses a multi-order-parameter state and belongs to a class of gyrotropic electrotoroidal compounds. Finally, application of electric fields to this mixed-phase system permits interconversion between the vortex and the ferroelectric phases concomitant with order-of-magnitude changes in piezoelectric and nonlinear optical responses. Our findings suggest new cross-coupled functionalities.

Published
2017

12. Risk Factors for Mortality in Pediatric Postsurgical versus Medical Severe Sepsis

Author

Fontela, P., Tucci, M., Dumistrascu, M., Skippen, P., Krahn, G., Bezares, E., Puig, G., Puig-Ramos, A., Garcia, R., Villar, M., Bigham, M., Polanski, T., Latifi, S., Giebner, D., Anthony, H., Hume, J., Galster, A., Linnerud, L., Sanders, R., Hefley, G., Madden, K., Thompson, A., Shein, S., Gertz, S., Han, Y., Williams, T., Hughes-Schalk, A., Chandler, H., Orioles, A., Zielinski, E., Doucette, A., Zebuhr, C., Wilson, T., Dimitriades, C., Ascani, J., Layburn, S., Valley, S., Markowitz, B., Terry, J., Morzov, R., Mcinnes, A., McArthur, J., Woods, K., Murkowski, K., Spaeder, M., Sharron, M., Wheeler, D., Beckman, E., Frank, E., Howard, K., Carroll, C., Nett, S., Jarvis, D., Patel, V., Higgerson, R., Christie, L., Typpo, K., Deschenes, J., Kirby, A., Uhl, T., Rehder, K., Cheifetz, I., Wrenn, S., Kypuros, K., Ackerman, K., Maffei, F., Bloomquist, G., Rizkalla, N., Kimura, D., Shah, S., Tigges, C., Su, F., Barlow, C., Michelson, K., Wolfe, K., Goodman, D., Campbell, L., Sorce, L., Bysani, K., Monjure, T., Evans, M., Totapally, B., Chegondi, M., Rodriguez, C., Frazier, J., Steele, L., Viteri, S., Costarino, A., Thomas, N., Spear, D., Hirshberg, E., Lilley, J., Rowan, C., Rider, C., Kane, J., Zimmerman, J., Greeley, C., Lin, J., Jacobs, R., Parker, M., Culver, K., Loftis, L., Jaimon, N., Goldsworthy, M., Fitzgerald, J., Weiss, S., Nadkarni, V., Bush, J., Diliberto, M., Allen, C., Gessouroun, M., Sapru, A., Lang, T., Alkhouli, M., Kamath, S., Friel, D., Daufeldt, J., Hsing, D., Carlo, C., Pon, S., Scimeme, J., Shaheen, A., Hassinger, A., Qiao, H., Giuliano, J., Tala, J., Vinciguerra, D., Fernandez, A., Carrero, R., Hoyos, P., Jaramillo, J., Posada, A., Izquiierdo, L., Olave, B.E. Piñeres, Donado, J., Dalmazzo, R., Rendich, S., Palma, L., Lapadula, M., Acuna, C., Cruces, P., De Clety, S. Clement, Dujardin, M., Berghe, C., Renard, S., Zurek, J., Steinherr, H., Mougkou, K., Critselis, E., Di Nardo, M., Picardo, S., Tortora, F., Rossetti, E., Fragasso, T., Cogo, P., Netto, R., Dagys, A., Gurskis, V., Kevalas, R., Neeleman, C., Lemson, J., Luijten, C., Wojciech, K., Pagowska-Klimek, I., Szczepanska, M., Karpe, J., Nunes, P., Almeida, H., Rios, J., Vieira, M., Iniguez, J. P. Garcia, Revilla, P., Urbano, J., Lopez-Herce, J., Bustinza, A., Palacios, A., Hofheinz, S., Rodriguez-Nunez, A., Sanagustin, S., Gonzalez, E., Riaza, M., Piaya, R., Soler, P., Esteban, E., Laraudogoitia, J., Monge, C., Herrera, V., Granados, J., Gonzalez, C., Koroglu, T., Ozcelik, E., Baines, P., Plunkett, A., Davis, P., George, S., Tibby, S., Harris, J., Agbeko, R., Lampitt, R., Brierley, J., Peters, M., Jones, A., Dominguez, T., Thiruchelvam, T., Deep, A., Ridley, L., Bowen, W., Levin, R., Macleod, I., Gray, M., Hemat, N., Alexander, J., Ali, S., Pappachan, J., McCorkell, J., Fortune, P., MacDonald, M., Hudnott, P., Suyun, Q., Singhi, S., Nallasamy, K., Lodha, R., Shime, N., Tabata, Y., Saito, O., Ikeyama, T., Kawasaki, T., Lum, L., Abidin, A., Kee, S., Tang, S., Jalil, R., Guan, Y., Yao, L., Lin, K., Ong, J., Salloo, A., Doedens, L., Mathivha, L., Reubenson, G., Moaisi, S., Pentz, A., Green, R., Schibler, A., Erickson, S., McEneiry, J., Long, D., Dorofaeff, T., Coulthard, M., Millar, J., Delzoppo, C., Williams, G., Morritt, M., Watts, N., Beca, J., Sherring, C., Bushell, T., Thakkar, Rajan K., Weiss, Scott L., Fitzgerald, Julie C., Keele, Luke, Thomas, Neal J., Nadkarni, Vinay M., Muszynski, Jennifer A., and Hall, Mark W.

Published
2019
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13. Multiferroic phase transition near room temperature in BiFeO3 films

Author

Infante, I. C., Juraszek, J., Fusil, S., Dupe, B., Gemeiner, P., Dieguez, O., Pailloux, F., Jouen, S., Jacquet, E., Geneste, G., Pacaud, J., Iniguez, J., Bellaiche, L., Barthelemy, A., Dkhil, B., and Bibes, M.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

In multiferroic BiFeO3 thin films grown on highly mismatched LaAlO3 substrates, we reveal the coexistence of two differently distorted polymorphs that leads to striking features in the temperature dependence of the structural and multiferroic properties. Notably, the highly distorted phase quasi-concomitantly presents an abrupt structural change, transforms from a hard to a soft ferroelectric and transitions from antiferromagnetic to paramagnetic at 360+/-20 K. These coupled ferroic transitions just above room temperature hold promises of giant piezoelectric, magnetoelectric and piezomagnetic responses, with potential in many applications fields.

Published
2011
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16. Molecular and dissociative absorption of multiple hydrogens on transition metal decorated C60

Author

Yildirim, T., Iniguez, J., and Ciraci, S.

Subjects
Condensed Matter - Materials Science
Abstract

Recently we have predicted [Phys. Rev. Lett. May 2005(cond-mat/0504694)] that Ti-decorated carbon nanotubes can absorb up to 8-wt% hydrogen at ambient conditions. Here we show that similar phenomena occurs in light transition-metal decorated C60. While Sc and Ti prefers the hexagon (H) sites with a binding energy of 2.1 eV, V and Cr prefers double-bond (D) sites with binding energies of 1.3 and 0.8 eV, respectively. Heavier metals such as Mn, Fe, and Co do not bond on C60. Once the metals are absorbed on C60, each can bind up to four hydrogen molecules with an average binding energy of 0.3-0.5 eV/H2. At high metal-coverage, we show that a C$_{60}$ can accommodate six D-site and eight H-site metals, which can reversible absorb up to 56 H2 molecules, corresponding to 7.5 wt%., Comment: 4+ pages, 5 figues, see http://www.ncnr.nist.gov/staff/taner/h2 Phys. Rev. B (submitted, 2005)

Published
2005
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17. Orbital and spin chains in ZnV2O4

Author

Lee, S. -H., Louca, D., Ueda, H., Park, S., Sato, T. J., Isobe, M., Ueda, Y., Rosenkranz, S., Zschack, P., Iniguez, J., and Osborn, R.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

Our powder inelastic neutron scattering data indicate that \zvo is a system of spin chains that are three dimensionally tangled in the cubic phase above 50 K due to randomly occupied $t_{2g}$ orbitals of V$^{3+}$ ($3d^2$) ions. Below 50 K in the tetragonal phase, the chains become straight due to antiferro-orbital ordering. This is evidenced by the characteristic wave vector dependence of the magnetic structure factor that changes from symmetric to asymmetric at the cubic-to-tetragonal transition.

Published
2003
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19. Universality Class of Thermally Diluted Ising Systems at Criticality

Author

Marques, M. I., Gonzalo, J. A., and Iniguez, J.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

The universality class of thermally diluted Ising systems, in which the realization of the disposition of magnetic atoms and vacancies is taken from the local distribution of spins in the pure original Ising model at criticality, is investigated by finite size scaling techniques using the Monte Carlo method. We find that the critical temperature, the critical exponents and therefore the universality class of these thermally diluted Ising systems depart markedly from the ones of short range correlated disordered systems. Our results agree fairly well with theoretical predictions previously made by Weinrib and Halperin for systems with long range correlated disorder., Comment: 7 pages, 6 figures, RevTex

Published
2000
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20. A 2D ferroelectric vortex pattern in twisted BaTiO3 freestanding layers.

Author

Sánchez-Santolino, G., Rouco, V., Puebla, S., Aramberri, H., Zamora, V., Cabero, M., Cuellar, F. A., Munuera, C., Mompean, F., Garcia-Hernandez, M., Castellanos-Gomez, A., Íñiguez, J., Leon, C., and Santamaria, J.

Abstract

The wealth of complex polar topologies1–10 recently found in nanoscale ferroelectrics results from a delicate balance between the intrinsic tendency of the materials to develop a homogeneous polarization and the electric and mechanical boundary conditions imposed on them. Ferroelectric–dielectric interfaces are model systems in which polarization curling originates from open circuit-like electric boundary conditions, to avoid the build-up of polarization charges through the formation of flux-closure11–14 domains that evolve into vortex-like structures at the nanoscale15–17 level. Although ferroelectricity is known to couple strongly with strain (both homogeneous18 and inhomogeneous19,20), the effect of mechanical constraints21 on thin-film nanoscale ferroelectrics has been comparatively less explored because of the relative paucity of strain patterns that can be implemented experimentally. Here we show that the stacking of freestanding ferroelectric perovskite layers with controlled twist angles provides an opportunity to tailor these topological nanostructures in a way determined by the lateral strain modulation associated with the twisting. Furthermore, we find that a peculiar pattern of polarization vortices and antivortices emerges from the flexoelectric coupling of polarization to strain gradients. This finding provides opportunities to create two-dimensional high-density vortex crystals that would enable us to explore previously unknown physical effects and functionalities.The stacking of freestanding ferroelectric perovskite layers with controlled twist angles results in a peculiar pattern of polarization vortices and antivortices that emerges from the flexoelectric coupling of polarization to strain gradients. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Author Correction: Local negative permittivity and topological phase transition in polar skyrmions

Author

Das, S., Hong, Z., Stoica, V. A., Gonçalves, M. A. P., Shao, Y. T., Parsonnet, E., Marksz, E. J., Saremi, S., McCarter, M. R., Reynoso, A., Long, C. J., Hagerstrom, A. M., Meyers, D., Ravi, V., Prasad, B., Zhou, H., Zhang, Z., Wen, H., Gómez-Ortiz, F., García-Fernández, P., Bokor, J., Íñiguez, J., Freeland, J. W., Orloff, N. D., Junquera, J., Chen, L. Q., Salahuddin, S., Muller, D. A., Martin, L. W., and Ramesh, R.

Published
2021
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22. A 2D ferroelectric vortex pattern in twisted BaTiO3freestanding layers

Author

Sánchez-Santolino, G., Rouco, V., Puebla, S., Aramberri, H., Zamora, V., Cabero, M., Cuellar, F. A., Munuera, C., Mompean, F., Garcia-Hernandez, M., Castellanos-Gomez, A., Íñiguez, J., Leon, C., and Santamaria, J.

Abstract

The wealth of complex polar topologies1–10recently found in nanoscale ferroelectrics results from a delicate balance between the intrinsic tendency of the materials to develop a homogeneous polarization and the electric and mechanical boundary conditions imposed on them. Ferroelectric–dielectric interfaces are model systems in which polarization curling originates from open circuit-like electric boundary conditions, to avoid the build-up of polarization charges through the formation of flux-closure11–14domains that evolve into vortex-like structures at the nanoscale15–17level. Although ferroelectricity is known to couple strongly with strain (both homogeneous18and inhomogeneous19,20), the effect of mechanical constraints21on thin-film nanoscale ferroelectrics has been comparatively less explored because of the relative paucity of strain patterns that can be implemented experimentally. Here we show that the stacking of freestanding ferroelectric perovskite layers with controlled twist angles provides an opportunity to tailor these topological nanostructures in a way determined by the lateral strain modulation associated with the twisting. Furthermore, we find that a peculiar pattern of polarization vortices and antivortices emerges from the flexoelectric coupling of polarization to strain gradients. This finding provides opportunities to create two-dimensional high-density vortex crystals that would enable us to explore previously unknown physical effects and functionalities.

Published
2024
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29. Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO2 Thin Films

Author

Silva, J. P. B., Negrea, R. F., Istrate, M. C., Dutta, S., Aramberri, H., Íñiguez, J., Figueiras, F. G., Ghica, C., Sekhar, K. C., and Kholkin, A. L.

Subjects
STRAINED FILMS, SPUTTERING, POLARIZATION, ZIRCONIA, STRONTIUM TITANATES, DEPOSITION TECHNIQUE, NANOTECHNOLOGY, FERROELECTRICITY, EPITAXIALLY STRAINED FILMS, ION-BEAM SPUTTERING DEPOSITION TECHNIQUE, ION BEAM SPUTTERING DEPOSITION, ELECTRIC FIELDS, FERROELECTRIC FILMS, WAKE UP, ION BEAMS, HAFNIUM OXIDES, THIN FILMS, FREE FILMS, RHOMBOHEDRAL ZRO2FILMS, ZRO 2 FILMS, COERCIVE FORCE, WAKE-UP FREE FILMS, EPITAXIALLY STRAINED FILM
Abstract

Zirconia- and hafnia-based thin films have attracted tremendous attention in the past decade because of their unexpected ferroelectric behavior at the nanoscale, which enables the downscaling of ferroelectric devices. The present work reports an unprecedented ferroelectric rhombohedral phase of ZrO2 that can be achieved in thin films grown directly on (111)-Nb:SrTiO3 substrates by ion-beam sputtering. Structural and ferroelectric characterizations reveal (111)-oriented ZrO2 films under epitaxial compressive strain exhibiting switchable ferroelectric polarization of about 20.2 μC/cm2 with a coercive field of 1.5 MV/cm. Moreover, the time-dependent polarization reversal characteristics of Nb:SrTiO3/ZrO2/Au film capacitors exhibit typical bell-shaped curve features associated with the ferroelectric domain reversal and agree well with the nucleation limited switching (NLS) model. The polarization-electric field hysteresis loops point to an activation field comparable to the coercive field. Interestingly, the studied films show ferroelectric behavior per se, without the need to apply the wake-up cycle found in the orthorhombic phase of ZrO2. Overall, the rhombohedral ferroelectric ZrO2 films present technological advantages over the previously studied zirconia- and hafnia-based thin films and may be attractive for nanoscale ferroelectric devices. © 2021 American Chemical Society. This work was supported by (i) the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contract UIDB/04650/2020 (ii) DST-SERB, Government of India, through Grant ECR/2017/00006, (iii) Project NECL - NORTE-01-0145-FEDER-022096 and Project UID/NAN/50024/2019. This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, refs UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. R.F.N., M.C.I,. and C.G. acknowledge the financial support from the Romanian Ministry of Education and Research within the project PN-III-P4-ID-PCCF2016-0047, contract 16/2018. Work at LIST was supported by the Luxembourg National Research Fund through projects PRIDE/15/10935404 “MASSENA” (S.D.) and INTER/ANR/16/11562984 “EXPAND” (H.A. and J.Í.). The authors acknowledge the CERIC–ERIC Consortium for access to experimental facilities and financial support under proposal 20192055. The authors also thank José Santos for technical support in the Thin Film Laboratory at CF-UM-UP. The equipment of the Ural Center for Shared Use “modern nanotechnology” Ural Federal University (Reg. No. 2968) was used with the financial support of the Ministry of Science and Higher Education of the RF (Project No. 075-15-2021-677).

Published
2021

40. Local negative permittivity and topological phase transition in polar skyrmions

Author

Das, S., primary, Hong, Z., additional, Stoica, V. A., additional, Gonçalves, M. A. P., additional, Shao, Y. T., additional, Parsonnet, E., additional, Marksz, E. J., additional, Saremi, S., additional, McCarter, M. R., additional, Reynoso, A., additional, Long, C. J., additional, Hagerstrom, A. M., additional, Meyers, D., additional, Ravi, V., additional, Prasad, B., additional, Zhou, H., additional, Zhang, Z., additional, Wen, H., additional, Gómez-Ortiz, F., additional, García-Fernández, P., additional, Bokor, J., additional, Íñiguez, J., additional, Freeland, J. W., additional, Orloff, N. D., additional, Junquera, J., additional, Chen, L. Q., additional, Salahuddin, S., additional, Muller, D. A., additional, Martin, L. W., additional, and Ramesh, R., additional

Published
2020
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