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Electric field modulation of magnetic properties via magnetoelectric coupling in composite materials is of fundamental and technological importance for realizing tunable energy efficient electronics. Here we provide foundational analysis on magnetoelectric voltage tunable inductor (VTI) that exhibits extremely large inductance tunability of up to 1150% under moderate electric fields. This field dependence of inductance arises from the change of permeability, which correlates with the stress dependence of magnetic anisotropy. Through combination of analytical models that were validated by experimental results, comprehensive understanding of various anisotropies on the tunability of VTI is provided. Results indicate that inclusion of magnetic materials with low magnetocrystalline anisotropy is one of the most effective ways to achieve high VTI tunability. This study opens pathway towards design of tunable circuit components that exhibit field-dependent electronic behavior. DARPA MATRIX; office of basic energy science, department of energy [DE-FG02-09ER46674]; AFOSR [FA9550-14-1-0376] The authors gratefully acknowledge the financial support from DARPA MATRIX program. The authors would also like to thank the Center for Energy Harvesting Materials and Systems (CEHMS) for providing access to industrial experts and equipment. S.G. would like to acknowledge the support from office of basic energy science, department of energy, through grant number DE-FG02-09ER46674. H.-C.S. would like to acknowledge the support from AFOSR through grant number FA9550-14-1-0376.

Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (< 2.5%) over the required temperature ranges specified in the standard industrial classifications. The compositional grading resulted in generation of internal bias field which enhanced the tunability due to increased nonlinearity. The electric field tunability of MLCCs provides an important avenue for design of miniature filters and power converters. DARPA MATRIX Program; Office of basic energy science, department of energy [DE-FG02-06ER46290]; office of naval research [N00014-16-1-3043] Financial support from DARPA MATRIX Program is acknowledged. The parallel computer simulations were performed on XSEDE supercomputers. D.M. and S.P. acknowledge the financial support from Office of basic energy science, department of energy (DE-FG02-06ER46290). Y.Y. acknowledges financial support from office of naval research through grant number (N00014-16-1-3043). Authors thanks AVX Corp. for the measurement on MLCC.

Continued emphasis on development of thermal cooling systems is being placed that can cycle low grade heat. Examples include solar powered unmanned aerial vehicles (UAVs) and data storage servers. The power efficiency of solar module degrades at elevated temperature, thereby, necessitating the need for heat extraction system. Similarly, data centres in wireless computing system are facing increasing efficiency challenges due to high power consumption associated with managing the waste heat. We provide breakthrough in addressing these problems by developing thermo-magneto-electric generator (TMEG) arrays, composed of soft magnet and piezoelectric polyvinylidene difluoride (PVDF) cantilever. TMEG can serve dual role of extracting the waste heat and converting it into useable electricity. Near room temperature second-order magnetic phase transition in soft magnetic material, gadolinium, was employed to obtain mechanical vibrations on the PVDF cantilever under small thermal gradient. TMEGs were shown to achieve high vibration frequency at small temperature gradients, thereby, demonstrating effective heat transfer. AMRDEC through Center for Energy Harvesting Materials and Systems (CEHMS); Institute of Critical Technology and Applied Science (ICTAS); AFOSR [FA9550-14-1-0376]; Office of Naval Research [N62909-16-1-2135] This work was supported by AMRDEC through Center for Energy Harvesting Materials and Systems (CEHMS). S.P. would like to thank Institute of Critical Technology and Applied Science (ICTAS) for supporting this work. M.-G.K. and H.-B.K. acknowledge the support from AFOSR through grant number #FA9550-14-1-0376. H.-C.S. would like to acknowledge the support from Office of Naval Research through grant number N62909-16-1-2135.

We report lead-free ferroelectric based resistive switching non-volatile memory (NVM) devices with epitaxial (1-x)BaTiO3-xBiFeO(3) (x = 0.725) (BT-BFO) film integrated on semiconducting (100) Nb (0.7%) doped SrTiO3 (Nb: STO) substrates. The piezoelectric force microscopy (PFM) measurement at room temperature demonstrated ferroelectricity in the BT-BFO thin film. PFM results also reveal the repeatable polarization inversion by poling, manifesting its potential for read-write operation in NVM devices. The electroforming-free and ferroelectric polarization coupled electrical behaviour demonstrated excellent resistive switching with high retention time, cyclic endurance, and low set/reset voltages. X-ray photoelectron spectroscopy was utilized to determine the band alignment at the BT-BFO and Nb: STO heterojunction, and it exhibited staggered band alignment. This heterojunction is found to behave as an efficient ultraviolet photo-detector with low rise and fall time. The architecture also demonstrates half-wave rectification under low and high input signal frequencies, where the output distortion is minimal. The results provide avenue for an electrical switch that can regulate the pixels in low or high frequency images. Combined this work paves the pathway towards designing future generation low-power ferroelectric based microelectronic devices by merging both electrical and photovoltaic properties of BT-BFO materials. NSF [ECCS-1348653]; office of basic energy science, Department of Energy [DE-FG02-06ER46290] S.K, B.C, H.-C.S, and P.K acknowledge NSF INAMM program for financial support. S.K would like to thank ICTAS NCFL for providing characterization facilities. M.C acknowledges the final support from NSF ECCS-1348653. S.P acknowledges the partial support through office of basic energy science, Department of Energy (DE-FG02-06ER46290). S.K also acknowledges Dr. Zhou for providing PFM training and ferroelectric target preparations and G. Ghosh for some technical helps.