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Your search keyword '"Sánchez, F."' showing total 138 results
Start Over Author "Sánchez, F." Journal applied physics letters
138 results on '"Sánchez, F."'

3. Polarization-dependent electrocaloric and pyroelectric effects in ferroelectric BaTiO3 thin films.

Author

Adkins, J. W., Fina, I., Sánchez, F., Bakaul, S. R., and Abiade, J. T.

Subjects
FERROELECTRIC thin films, PYROELECTRICITY, FERROELECTRICITY, PHOTOVOLTAIC effect, THIN films, INDUCTIVE effect, ELECTRIC fields
Abstract

Herein, we examine the influence of controllable polarization reversal and built-in electric fields on pyroelectric and electrocaloric effects in a BaTiO3 thin film using a modified indirect method. We find that the magnitude of the sample's change in polarization with temperature is sensitive to the degree of polarization reversal. The pyroelectric response is small at low fractions of switched polarization and grows larger by several factors as larger fractions of polarization are reversed. This polarization reversal-sensitive pyroelectric behavior is the result of an internal built-in field, which has the effect of destabilizing low fractions of switched polarization and producing diminished pyroelectric effect. Greater fractions of switched polarization are more stable against backswitching and permit a larger pyroelectric response. Our findings highlight a characterization method for polarization-dependent pyroelectric effects in ferroelectric thin films, where built-in field effects are also present. [ABSTRACT FROM AUTHOR]

Published
2023
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9. Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates.

Author

Lyu, J., Fina, I., Bachelet, R., Saint-Girons, G., Estandía, S., Gázquez, J., Fontcuberta, J., and Sánchez, F.

Subjects
FERROELECTRICITY, EPITAXIAL layers, THIN films, ELECTRODES, POLARIZATION (Electricity), COMPUTER storage devices
Abstract

SrTiO3 templates have been used to integrate epitaxial bilayers of ferroelectric Hf0.5Zr0.5O2 and La2/3Sr1/3MnO3 bottom electrodes on Si(001). The Hf0.5Zr0.5O2 films show enhanced properties in comparison to equivalent films on SrTiO3(001) single crystalline substrates. The films, thinner than 10 nm, have a very high remnant polarization of 34 μC/cm2. Hf0.5Zr0.5O2 capacitors at an operating voltage of 4 V present a long retention time well beyond 10 years and high endurance against fatigue up to 109 cycles. The robust ferroelectric properties displayed by the epitaxial Hf0.5Zr0.5O2 films on Si(001) using SrTiO3 templates pave the way for the monolithic integration on silicon of emerging memory devices based on epitaxial HfO2. [ABSTRACT FROM AUTHOR]

Published
2019
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11. Robust ferroelectricity in epitaxial Hf1/2Zr1/2O2 thin films.

Author

Lyu, J., Fina, I., Solanas, R., Fontcuberta, J., and Sánchez, F.

Subjects
FERROELECTRIC crystals, THIN films, PULSED laser deposition, ORTHORHOMBIC crystal system, POLARIZATION (Electricity), ELECTRIC fields, FERROELECTRICITY
Abstract

Ferroelectric orthorhombic Hf0.5Zr0.5O2 thin films have been stabilized epitaxially on La2/3Sr1/3MnO3/SrTiO3(001) by pulsed laser deposition. The epitaxial orthorhombic films, (111)-oriented and with a very flat surface, show robust ferroelectric properties at room temperature. They present a remnant polarization around 20 μC/cm2 without the need of a wake-up process, a large coercive electric field of around 3 MV/cm, an extremely long retention extending well beyond 10 years, and an endurance up to about 108 cycles. Such outstanding properties in the nascent research on epitaxial HfO2-based ferroelectric films can pave the way for a better understanding of the effects of orientation, interfaces, strain, and defects on ferroelectricity in HfO2. [ABSTRACT FROM AUTHOR]

Published
2018
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14. Extra-low thermal conductivity in unfilled CoSb3-δ skutterudite synthesized under high-pressure conditions.

Author

Prado-Gonjal, J., Serrano-Sánchez, F., Nemes, N. M., Dura, O. J., Martínez, J. L., Fernández-Díaz, M. T., Fauth, F., and Alonso, J. A.

Subjects
*THERMOELECTRIC materials, *SKUTTERUDITE, *CHEMICAL synthesis, *X-ray powder diffraction, *PHONON scattering
Abstract

Thermoelectric CoSb3-δ skutterudite was synthesized and sintered in one step under high-pressure conditions at 3.5 GPa in a piston-cylinder hydrostatic press. Structural analysis carried out from synchrotron x-ray powder diffraction data reveals a significant Sb deficiency in this material. The introduction of point defects in the form of Sb vacancies distributed at random in the structure leads to an impressive reduction (>50%) of the total thermal conductivity, k, which is one of the main ingredients of good thermoelectric materials. This suggests phonon scattering effects originated in the Sb defects, which drives to a better improvement in k than that achieved by the conventional strategy of filling the cages of the skutterudite structure with rare earths or other heavy cations. In parallel, changes in the electronic band structure caused by point variation of the stoichiometry produce an undesired increment in the electrical resistivity. Nevertheless, the low thermal conductivity combined with a high Seebeck coefficient (-434μV-1 at 500 K) originates a relatively large figure of merit (ZT=0.12 at 550 K) for CoSb2.90(2). [ABSTRACT FROM AUTHOR]

Published
2017
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19. High ferroelectric polarization in c-oriented BaTiO3 epitaxial thin films on SrTiO3/Si(001).

Author

Scigaj, M., Chao, C. H., Gázquez, J., Fina, I., Moalla, R., Saint-Girons, G., Chisholm, M. F., Herranz, G., Fontcuberta, J., Bachelet, R., and Sánchez, F.

Subjects
EPITAXY, EPITAXIAL layers, FERROELECTRICITY, ELECTRIC properties of crystals, POLARIZATION (Electricity)
Abstract

The integration of epitaxial BaTiO3 films on silicon, combining c-orientation, surface flatness, and high ferroelectric polarization is of main interest towards its use in memory devices. This combination of properties has been only achieved so far by using yttria-stabilized zirconia buffer layers. Here, the all-perovskite BaTiO3/LaNiO3/SrTiO3 heterostructure is grown monolithically on Si(001). The BaTiO3 films are epitaxial and c-oriented and present low surface roughness and high remnant ferroelectric polarization around 6 µC/cm². This result paves the way towards the fabrication of lead-free BaTiO3 ferroelectric memories on silicon platforms. [ABSTRACT FROM AUTHOR]

Published
2016
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41. Controlling magnetic domain wall motion in the creep regime in He+-irradiated CoFeB/MgO films with perpendicular anisotropy.

Author

Diez, L. Herrera, García-Sánchez, F., Adam, J.-P., Devolder, T., Eimer, S., El Hadri, M. S., Lamperti, A., Mantovan, R., Ocker, B., and Ravelosona, D.

Subjects
*MAGNETIC domain walls, *COBALT compounds, *HELIUM spectra, *MAGNESIUM oxide, *MAGNETIC anisotropy, *CREEP (Materials)
Abstract

This study presents the effective tuning of perpendicular magnetic anisotropy in CoFeB/MgO thin films by He+ ion irradiation and its effect on domain wall motion in a low field regime. Magnetic anisotropy and saturation magnetisation are found to decrease as a function of the irradiation dose which can be related to the observed irradiation-induced changes in stoichiometry at the CoFeB/MgO interface. These changes in the magnetic intrinsic properties of the film are reflected in the domain wall dynamics at low magnetic fields (H) where irradiation is found to induce a significant decrease in domain wall velocity (v). For all irradiation doses, domain wall velocities at low fields are well described by a creep law, where Ln(v) vs. H-1/4 behaves linearly, up to a maximum field H*, which has been considered as an approximation to the value of the depinning field Hdep. In turn, H* ≈ Hdep is seen to increase as a function of the irradiation dose, indicating an irradiation-induced extension of the creep regime of domain wall motion. [ABSTRACT FROM AUTHOR]

Published
2015
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44. Exchange biasing and electric polarization with YMnO3

Author

Martí, X., primary, Sánchez, F., additional, Hrabovsky, D., additional, Fàbrega, L., additional, Ruyter, A., additional, Fontcuberta, J., additional, Laukhin, V., additional, Skumryev, V., additional, García-Cuenca, M. V., additional, Ferrater, C., additional, Varela, M., additional, Vilà, A., additional, Lüders, U., additional, and Bobo, J. F., additional

Published
2006
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46. Monolithic integration of spectrally selective uncooled lead selenide detectors for low cost applications

Author

Diezhandino, J., primary, Vergara, G., additional, Pérez, G., additional, Génova, I., additional, Rodrigo, M. T., additional, Sánchez, F. J., additional, Torquemada, M. C., additional, Villamayor, V., additional, Plaza, J., additional, Catalán, I., additional, Almazán, R., additional, Verdú, M., additional, Rodrı́guez, P., additional, Gómez, L. J., additional, and Montojo, M. T., additional

Published
2003
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50. Yttria-stabilized zirconia/SrTiO3 oxide heteroepitaxial interface with symmetry discontinuity.

Author

Scigaj, M., Dix, N., Cabero, M., Rivera-Calzada, A., Santamaria, J., Fontcuberta, J., Herranz, G., and Sánchez, F.

Subjects
YTTRIA stabilized zirconium oxide, CRYSTAL symmetry, ATOMIC layer epitaxial growth, STRONTIUM titanate, ATOMIC force microscopy
Abstract

We show that yttria-stabilized zirconia (YSZ) films deposited on structurally dissimilar SrTiO3(110) substrates exhibit two-dimensional layer-by-layer growth. We observed that, up to a thickness of about 15 nm, the square (001) basal plane of the cubic YSZ grows epitaxially on the rectangular (110) crystallographic plane of SrTiO3 substrates, with [110]YSZ(001)// [001]SrTiO3(110) epitaxial relationship. Thus, the heterointerface presents symmetry discontinuity between the YSZ(001) film and the lower surface symmetry SrTiO3(110) substrate. Beyond this specific case, we envisage similar approaches to develop other innovative oxide interfaces showing similar crystal symmetry discontinuities. [ABSTRACT FROM AUTHOR]

Published
2014
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