Solid-state dielectric film capacitors with high-energy-storage density will further promote advanced electronic devices and electrical power systems toward miniaturization, lightweight, and integration. In this study, the influence of interface and thickness on energy storage properties of SrTiO (STO) films grown on LaSrMnO (LSMO) electrode are systematically studied. The cross-sectional high resolution transmission electron microscopy reveals an ion interdiffusion layer and oxygen vacancies at the STO/LSMO interface. The capacitors show good frequency stability and increased dielectric constant with increasing STO thickness (410-710 nm). The breakdown strength (E) increases with decreasing STO thickness and reaches 6.8 MV/cm. Interestingly, the E under positive field is enhanced significantly and an ultrahigh energy density up to 307 J/cm with a high efficiency of 89% is realized. The enhanced E may be related to the modulation of local electric field and redistribution of oxygen vacancies at the STO/LSMO interface. Our results should be helpful for potential strategies to design devices with ultrahigh energy density.

Ferroic‐order‐based devices are emerging as alternatives to high density, high switching speed, and low‐power memories. Here, multi‐nonvolatile resistive states with a switching speed of 6 ns and a write current density of about 3 × 103 A cm−2 are demonstrated in crossbar‐structured memories based on all‐oxide La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions. The tunneling resistive switching as a function of voltage pulse duration time, associated with the ferroelectric domain reversal dynamics, is ruled by the Kolmogorov–Avrami–Ishibashi switching model with a Lorentzian distribution of characteristic switching time. It is found that the characteristic resistance switching time decreases with increasing voltage pulse amplitude following Merz's law and the estimated write speed can be less than 6 ns at a relatively higher voltage. These findings highlight the potential application of multiferroic devices in high speed, low power, and high‐density memories.

better uniformity. [20] While for URS mode, owing to the single polarity operation, it allows a diode as the selector in crossbar arrays to settle the sneak-path issue. [21] And this passive crossbar array with one diode-one resistor (1D1R) structure offers advantages in achieving the highest integration density of 4F 2 [22] as well as enables simplified peripheral control elements to support large-scale integrated circuits. [23] To date, reliable BRS and URS behaviors have been observed in a wide variety of materials, including binary metal oxides HfO 2 , TaO x , ZnO, WO x , NiO, etc. [24][25][26][27][28][29] Beneficial to high density data storage, multilevel switchings have also been demonstrated in both BRS [24,25,30,31] and URS [27,32] devices, as well as devices with atypical coexistent BRS and URS. [33,34] Furthermore, in order to catch the speed of the microprocessor working in gigahertz lockstep, sub-nanosecond operation speed is required for nextgeneration memories, which has been obtained in BRS devices with binary memory states but was not achieved in any multilevel RRAMs. For example, operation speeds as fast as 300 and 100 ps were achieved in HfO x and Pt-SiO 2 based BRS RRAMs, respectively, [35][36][37] while the reliable multilevel control in BRS RRAMs was only obtained with operation speed of dozens or even hundreds of nanoseconds. [24,27,31,32] By comparison, no sub-nanosecond multilevel switchings were reported in URS RRAM. Therefore, it will be interesting to study the sub-nanosecond operating ability in a URS device, in which a typical high off/on resistance ratio may be able to host multilevel resistance states with ultrafast operation speed.As an important magnetic insulator, yttrium iron garnet Y 3 Fe 5 O 12 (YIG) has been used in microwave, acoustic, optical, and magneto-optical applications, as well as spintronic devices owing to its low damping constant and insulating ferromagnetic nature. [38][39][40] Besides the well-known magneto-optical memory applications for YIG, early in 1970, Bullock et al. found a repeatable URS behavior in Si-doped YIG crystal. [41] This discovery demonstrates the possible application of YIG as an RRAM device, but no further resistive switching investigations were carried out since then. The high performance of the Au/YIG/n-Si RRAM cells was herein reported with sub-nanosecond switching speed, high off/on resistance ratio, well endurance, and reliable retention at both room temperature and 85 °C. Multi resistance states were achieved during the DC voltage sweep as well as ultrafast pulse operation. Furthermore, YIG-based RRAM is fabricated on silicon substrate, further illustrating its promising potential for commercial application in memories.Resistive random access memory (RRAM) with ultrafast and multilevel switching is extremely promising for next-generation nonvolatile memory. Here, ultrafast unipolar resistive switchings (≈540 ps) with high off/on resistance ratio (≈10 4 ) are obtained in yttrium iron garnet Y 3 Fe 5 O 12 (YIG)-based resistive memory on ...

Electric-field control of magnetism is a key issue for the future development of low-power spintronic devices. By utilizing the opposite strain responses of the magnetic anisotropies in Co and Ni films, a Co/Cu/Ni/0.7Pb(MgNb)O-0.3PbTiO (PMN-PT) spin-valve/piezoelectric heterostructure with ∼7 nm Cu spacer layer was properly designed and fabricated. The purely electric-field-controlled nonvolatile and reversible magnetization rotations in the Co free layer were achieved, whereas the magnetization of the Ni fixed layer was almost unchanged. Accordingly, not only the electroresistance but also the electric-field-tuned magnetoresistance effects were obtained, and more importantly at least six nonvolatile magnetoresistance states in the strain-tuned spin valve were achieved by setting the PMN-PT into different nonvolatile piezo-strain states. These findings highlight potential strategies for designing electric-field-driven multistate spintronic devices.

Control over nonvolatile magnetization rotation and resistivity change by an electric field in La0.6Sr0.4MnO3 thin films grown on (011) oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 substrates are studied. By utilizing an in-plane strain induced by a side ferroelectric switching with pulsed electric fields from −2.5 kV/cm to +5 kV/cm along [011¯], a nonvolatile and reversible 90°-rotation of the magnetic easy-axis is achieved, corresponding to −69.68% and +174.26% magnetization switching along the [100] and [011¯] directions, respectively. The strain induced nonvolatile resistivity change is approximately 3.6% along the [011¯] direction. These findings highlight potential strategies for electric-field-driven spintronic devices.

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(1–x)(0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-xBiFeO3 (0 ≤x≤ 0.9) ternary ceramics were prepared by the modified Pechini method. X ray diffraction patterns manifest that the samples undergo a gradual structural transformation from the rhombohedral-tetragonal morphotropic phase boundary to the rhombohedral phase with the increasing content of BiFeO3. Room temperature ferromagnetism was observed in BiFeO3-rich samples with x ≥ 0.6, and this ferromagnetism can be ascribed to the suppression of the spiral spin structure with the canting of antiferromagnetically ordered spins. The BiFeO3-rich samples (x = 0.6–0.8) exhibit superior ferroelectric properties with the maximum remanent polarization of 44.7 μC/cm2, as confirmed by the positive-up negative-down measurement to exclude the contribution of leakage current. The coexistence of room-temperature ferromagnetism and ferroelectricity manifests that the lead-free BiFeO3-based solid solutions are quite promising multiferroic materials and may be important for potential applications in BFO-based magnetoelectric devices.

Sub‐nanosecond (≈540 ps) resistive switching with high off/on resistance ratio is demonstrated in an Au/YIG/n‐Si resistive random access memory (RRAM) at room temperature and 85 °C in article number https://doi.org/10.1002/aelm.201800418 by Yuewei Yin, Xiaoguang Li, and co‐workers. Five discrete resistance levels with ultrafast switching clearly show reliable retentions. Such an RRAM is promising for next‐generation non‐volatile memories with ultrahigh speed, low power consumption, and high density.