Multiferroic (MF)-magnetoelectric (ME) composites, which integrate magnetic and ferroelectric materials, exhibit a higher operational temperature (above room temperature) and superior (several orders of magnitude) ME coupling when compared to single-phase multiferroic materials. Room temperature control and the switching of magnetic properties via an electric field and electrical properties by a magnetic field has motivated research towards the goal of realizing ultralow power and multifunctional nano (micro) electronic devices. Here, some of the leading applications for magnetoelectric composites are reviewed, and the mechanisms and nature of ME coupling in artificial composite systems are discussed. Ways to enhance the ME coupling and other physical properties are also demonstrated. Finally, emphasis is given to the important open questions and future directions in this field, where new breakthroughs could have a significant impact in transforming scientific discoveries to practical device applications, which can be well-controlled both magnetically and electrically.

Transition metal carbides (MXenes) are an emerging family of highly conductive two-dimensional materials with additional functional properties introduced by surface terminations. Further modification of the surface terminations makes MXenes even more appealing for practical applications. Herein, we report a facile and environmentally benign synthesis of reduced Ti₃C₂T_x MXene (r-Ti₃C₂T_x) via a simple treatment with L-ascorbic acid at room temperature. r-Ti₃C₂T_x shows a six-fold increase in electrical conductivity, from 471 ± 49 for regular Ti₃C₂T_x to 2819 ± 306 S m⁻¹ for the reduced version. Additionally, we show an enhanced oxidation stability of r-Ti₃C₂T_x as compared to regular Ti₃C₂T_x. An examination of the surface-enhanced Raman scattering (SERS) activity reveals that the SERS enhancement factor of r-Ti₃C₂T_x is an order of magnitude higher than that of regular Ti₃C₂T_x. The improved SERS activity of r-Ti₃C₂T_x is attributed to the charge transfer interaction between the MXene surface and probe molecules, re-enforced by an increased electronic density of states (DOS) at the Fermi level of r-Ti₃C₂T_x. The findings of this study suggest that reduced MXene could be a superior choice over regular MXene, especially for the applications that employ high electronic conductivity, such as electrode materials for batteries and supercapacitors, photodetectors, and SERS-based sensors.

We report the breakdown electric field and energy density of laser ablated BaTiO(3)/Ba((1-x))Sr(x)TiO(3) (x = 0.7) (BT/BST) relaxor-ferroelectric superlattices (SLs) grown on (100) MgO single crystal substrates. The dielectric constant shows a frequency dispersion below the dielectric maximum temperature (T(m)) with a merger above T(m) behaving similarly to relaxors. It also follows the basic criteria of relaxor ferroelectrics such as low dielectric loss over wide temperature and frequency, and 50 K shift in T(m) with change in probe frequency; the loss peaks follow a similar trend to the dielectric constant except that they increase with increase in frequency (~40 kHz), and satisfy the nonlinear Vogel-Fulcher relation. Well-saturated ferroelectric hysteresis and 50-80% dielectric saturation are observed under high electric field (~1.65 MV cm(-1)). The superlattices demonstrate an 'in-built' field in as grown samples at low probe frequency (1 kHz) which rules out the effect of any space charge and interfacial polarization. The P-E loops show around 12.24 J cm(-3) energy density within the experimental limit, but extrapolation of this data suggests that the potential energy density could reach 46 J cm(-3). The current density versus applied electric field indicates an exceptionally high breakdown field (5.8-6.0 MV cm(-1)) and low current density (~10-25 mA cm(-2)) near the breakdown voltage. The current-voltage characteristics reveal that the space charge limited conduction mechanism prevails at very high voltage.

We describe systematic studies on Nd and Mn co-doped BiFeO₃, i.e., (Bi_0.95Nd_0.05)(Fe_0.97Mn_0.03)O₃ (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO₃ (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620 K observed near the Néel temperature ($T_N$ ∼ 643 K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Néel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient.