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The artificial multiferroic heterostructure used in this work is composed by an yttrium iron garnet (YIG) film deposited by radio frequency (rf) magnetron sputtering on a metalized PMN-PZT ceramic. We demonstrate, thanks to the well-known converse magnetoelectric (CME) coupling, the control of the magnetic state of the YIG film by means of a low electric field applied to the PMN-PZT ceramic. In particular, it is shown that the variations of the magnetization induced by the strain are functions of the magnetic sate of the film. It is shown that the maximum amplitude variation is observed at the coercive magnetic field (Hc), whereas when H increases, the strain effect has a limited impact on the film magnetization. A second effect has also been remarked on the magnetization of the YIG film but only after the first strain induced cycle has been applied. These variations, observed only under low applied magnetic fields, can be attributed to the re-orientation of some magnetic moments which are easy to switch under low magnetic fields. We find that after poling the YIG film, i.e., applying a magnetic field on it, the initial state is restored. The CME coupling coefficient is determined for different magnetic states of the YIG film, and the maximum value 11 × 10−8 s/m is obtained at H = Hc and E = Ec (the coercive field of the PMN-PZT ceramic). The relative susceptibility tunability available for the heterostructure proposed is 16.8% for an electric field applied between 0 and −4 kV/cm. [ABSTRACT FROM AUTHOR]

Ba0.63Sr0.37TiO3 (BST) films were first deposited on SiC substrates with LNO bottom electrodes by magnetron sputtering. The BST/LNO/SiC thin films exhibit high dielectric tunability and low dielectric loss while maintaining excellent temperature coefficient of dielectric constant in the temperature range between 250 and 350 K. We also investigated the effect of film thickness on the dielectric properties. BST(430 nm)/LNO/SiC film has higher tunability (68.09% @700 kV/cm), lower loss tangent (tanδ = 0.00987) and quite a bit higher figure of merit (FOM = 68.99) as compared with that of BST(300 nm)/LNO/SiC film. Our results demonstrate that combining ferroelectric BST films with SiC substrates is very promising for the development of tunable devices over a large temperature range. [ABSTRACT FROM AUTHOR]

Abstract: Highly (001) oriented (K,Na)NbO3 lead-free piezoelectric films were fabricated on SrRuO3 buffered SrTiO3(001) single crystal substrates by RF magnetron sputtering. The films showed a stable frequency dependence of dielectric permittivity and loss tangent in the range of 1kHz–1MHz. A fairly high tunability of 69.7% (@400kV/cm) was obtained in the films. Well saturated P–E hysteresis loops were obtained at E=250kV/cm, the remnant polarization P r was 8μC/cm2, and coercive field E c was only 40kV/cm. These films showed a fatigue-free behavior up to 1010 switching cycles. The decreased coercive field, improved dielectric and fatigue properties may be related to SRO bottom electrodes, which can efficiently suppress the “dead layer” near the ferroelectric-electrode interface. The leakage current density of the films was only 3.48×10−6 A/cm2 at the electric field of 250kV/cm, which is even lower than that of Mn-doped KNN films. In addition, the piezoelectric constant d 33 was estimated to be 36pm/V. [Copyright &y& Elsevier]

Highly (001) oriented ( K, Na) NbO3 ( KNN) lead-free piezoelectric thin films were grown on LaNiO3 ( LNO)-coated silicon by RF magnetron sputtering. The effects of the top electrodes on the electrical properties of KNN thin films were investigated. The dielectric and piezoelectric properties were remarkably improved in LNO/ KNN/ LNO (εr = 899 at 1 kHz, d33 = 58 pm/V), compared with that in Pt/ KNN/ LNO (εr = 584 at 1 kHz, d33 = 26 pm/V). An enhanced ferroelectricity was also obtained in LNO/ KNN/ LNO, with a remnant polarization of 12 μC/cm2 and a maximum polarization of 23 μC/cm2 at the applied field of 200 kV/cm. Besides, the temperature dependence of piezoelectricity of the films was characterized in this study. [ABSTRACT FROM AUTHOR]

Abstract: (K,Na)NbO3 ferroelectric films were grown on LaNiO3 coated silicon substrates by RF magnetron sputtering. The conductive LaNiO3 films acted as seed layers and induced the highly (001) oriented perovskite (K,Na)NbO3 films. Such films exhibit saturated hysteresis loops and have a remnant polarization (2P r) of 23μC/cm2, and coercive field (2E c) of 139kV/cm. The films showed a fatigue-free behavior up to 109 switching cycles. A high tunability of 65.7% (@300kV/cm) was obtained in the films. The leakage current density of the films is about 6.0×10−8 A/cm2 at an electric field of 50kV/cm. [Copyright &y& Elsevier]

Abstract: Highly (110)- and (100)-oriented LaNiO3 (LNO) thin films were successfully grown on Si (100) substrate using radio frequency (RF) magnetron sputtering at room temperature (RT). Effects of oxygen partial pressures on the orientation, film composition, surface morphology, and electrical properties of the films were investigated. The nearly complete (100) orientation was first achieved with oxygen partial pressure beyond 15% in the sputtering gas. The preferred (100) orientation of growing films is determined by uniform distribution of Ni3+ and La/Ni ratio in the films caused by oxygen during sputtering, as well as the lowest surface energy of the films in the crystalline process. LNO films with controlled orientation have low resistivity of 7.0×10−6 Ωm which is a good basis for integrating ferroelectric capacitors. [Copyright &y& Elsevier]

Highly (100) oriented lead strontium titanate ( Pb0.4 Sr0.6 TiO3) thin films were deposited on LaNiO3 -coated Si substrate via radio-frequency magnetron sputtering method with substrate temperature ranging from 300 to 500°C. The PST thin films were crystallized at a temperature as low as 300°C, which may result from the well-controlled stoichiometry and the in situ crystallization on seed layer. At an electric field of 400 kV/cm, high tunability of 43% and 57% can be achieved for PST films deposited at 300°C and 500°C, respectively. Moreover, the dielectric response shows weak frequency dependence and the loss factor stays relatively low. The results suggest that such films should be promising candidate for the microwave tunable devices compatible with the current Si technology. [ABSTRACT FROM AUTHOR]

Perovskite Ba0.6Sr0.4TiO3 (BST) thin films have been grown on Al2O3(0001) substrates without/with inserting an ultrathin TiOx seeding layer by rf magnetron sputtering. X-ray diffraction and pole figure studies reveal that the film with the TiOx layer (12-Å-thick) is highly oriented along the (111) direction and exhibits a good in-plane relationship of BST(111)∥Al2O3(0001). The high frequency dielectric measurements demonstrate that the complex permittivity ([variant_greek_epsilon]=[variant_greek_epsilon]′-j[variant_greek_epsilon]″) is well described by a Curie-von Scheidler dispersion with an exponent of 0.40. The resulting epitaxial BST films show high permittivity (∼428) and tunability (∼41%, at 300 kV/cm and 40 GHz) and their microwave properties (1-40 GHz) potentially could be made suitable for tunable devices. [ABSTRACT FROM AUTHOR]

Crack-free Yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) thin films were successfully deposited on Si/SiO 2 substrates by RF magnetron sputtering, through controlling the annealing temperature and cooling rate during post-annealing process. The annealing condition dependences of crystallinity, microstructures and magnetic properties of YIG films were investigated. With the increase of the annealing temperature, the saturation magnetization of YIG films increases and the coercive field decreases, while the ferromagnetic resonance (FMR) linewidth becomes wider. The films annealed at 750 °C with cooling rate of 1 °C/min are crack-free and present excellent comprehensive performances, the corresponding coercive field is 32 Oe and the FMR linewidth is 57 Oe at 9.4 GHz. These results indicate that high-quality crack-free YIG films with excellent magnetic properties can be achieved on Si/SiO 2 substrates by controlling the annealing process, which makes it more convenient to fabricate low-loss microwave integrated devices. [ABSTRACT FROM AUTHOR]

Highly (001)-oriented pure PbZrO 3 (PZO) films and Sn-substituted PZO films are deposited on (001)-LaNiO 3 buffered SiO 2 /Si substrates by RF magnetron sputtering. Different Sn-substituted PbZrO 3 films (PbZr 1-x Sn x O 3 , x = 0%, 3%, 5%, 10%) with orthorhombic anti-ferroelectric phase are fabricated. The effects of Sn substitution on structure and energy performance have been investigated in detail. The switching electric fields are enlarged and energy loss is lowered by Sn substitution. Recoverable energy density (Wr) of 14.8 ± 0.2 J/cm 3 and energy efficiency (η) of 71.2 ± 0.5% at 900 kV/cm are obtained in 5% Sn-substituted PZO film (~ 360 nm). Furthermore, with thicker thickness of ~ 650 nm, Wr and η can be further improved. The Sn-substituted PZO film is believed to be an improved material for applications in energy storage systems and 5% Sn-substituted PZO film exhibits the highest Wr and η in this work. [ABSTRACT FROM AUTHOR]

SrRuO 3 (SRO) thin films were grown on SiO 2 /Si substrates with different thickness of LaNiO 3 (LNO) seed layers by RF magnetron sputtering. Effects of LNO thickness on the grain orientation, surface morphology, magnetic behavior and electrical transport properties of SRO films were investigated. The orientation of SRO films transformed from (110) pc to (001) pc and the residual stress was released gradually with increasing the thickness (pc refers to the pseudo-cubic unit cell of SrRuO 3 ). SRO films with higher orientation grown on LNO exhibited more flat surface, higher saturation magnetization, and lower coercive field. The magnetic anisotropy was enhanced on thicker LNO due to the different states of residual stress. In addition, the temperature dependence of resistivity was promoted by the microstructural disorder. (110) pc -oriented SRO monolayer electrode and (001) pc -oriented SRO/LNO300 bilayer electrode own low room temperature sheet resistance of 0.38 Ω/□ and 0.26 Ω/□, respectively. The results indicate that the controllable SRO films can be used as not only good bottom electrodes but also promising templates to control the crystallographic orientations of various other perovskite-based functional materials. [ABSTRACT FROM AUTHOR]

Abstract: We report the fabrication of Pb0.4Sr0.6TiO3 thin films with different microstructures and dielectric responses deposited on LaNiO3 buffered silicon substrate via the RF magnetron sputtering method with various deposition powers from 40W to 120W. Effects of the power on deposition rate, orientation, surface morphology and dielectric response were investigated. X-ray diffraction patterns indicated that the crystal orientation of thin films changes from (110) preferential orientation to random orientation with decreasing power, and finally to perfect (100) orientation. Moreover, the thin films prepared at lower power show more homogeneous grain size distribution and denser microstructure. The capacitance–voltage analysis revealed that the films deposited at lower powers show larger dielectric response and better tunability performance. Especially, large dielectric constant and tunability of 947 and 80.88% (@400kV/cm), respectively, were obtained under a deposition power of 40W. [Copyright &y& Elsevier]

Abstract: This investigation presents the growth of (100), (110) and preferential (111)-oriented Pb0.6Sr0.4TiO3 thin films prepared on different orientations LaNiO3 buffered silicon substrates via radio-frequency magnetron sputtering method. The effects of the orientation on microstructure and dielectric response were systematically investigated. The capacitance–voltage property versus the crystallographic orientation analysis revealed that preferential (111)-orientation film possesses the largest relative permittivity and tunability of 1180 and 84% (at 400kV/cm) respectively, which are much higher than those of (100)- and (110)-oriented thin films. These results suggest preferential (111)-orientation films as promising candidates for microwave tunable devices. [Copyright &y& Elsevier]

Abstract: This investigation presents a novel method to prepare Pb0.4Sr0.6TiO3 thin films crystallized at relatively low temperature with different microstructures and enhanced tunability performance on LaNiO3 buffered SiO2/Si substrates. The incorporation of oxygen during the ex-situ RF magnetron sputtering unusually changes the microstructure of the films and remarkably improves the tunability because of the modulated dielectric constant with and without electric field. The dielectric response versus the DC electric field analysis revealed that the tunablity increased from 61.6% to 73.4% at ±400kV/cm with increasing content of oxygen while the loss factor retained relatively low, suggesting the film could be one of the promising candidates for the microwave tunable devices compatible with Si integrated circuits. [Copyright &y& Elsevier]