Multiferroic heterostructures and tunneling junctions

AbstractMultiferroic heterostructures showing both electric and magnetic orders have attracted much attention because of their promising applications in the next generation of memories, sensors, and microwave devices and so on. The complex electronic and magnetic orders at the interface in multiferroic heterostructures will cause abundant physical phenomena due to the interplay among spin, charge, orbit, and lattice degrees of freedom, and various prototype devices have been achieved. In this review, we summarize some recent progresses mainly in the strain- and charge-mediated effects on the magnetic and electronic transport properties manipulated by electric/magnetic fields in multiferroic heterostructures. The recent advances in multiferroic tunnel junctions with ferroelectric barriers by using the spin polarized nature of magnetic materials are particularly presented, which exhibit magnetoelectric coupling effects at the interface and multi-stable resistance states in a single memory unit cell. Finally, the new inspiration for the design of spintronic devices having more energy efficiency and higher density is discussed

Mechanical-Resonance-Enhanced Thin-Film Magnetoelectric Heterostructures for Magnetometers, Mechanical Antennas, Tunable RF Inductors, and Filters

The strong strain-mediated magnetoelectric (ME) coupling found in thin-film ME heterostructures has attracted an ever-increasing interest and enables realization of a great number of integrated multiferroic devices, such as magnetometers, mechanical antennas, RF tunable inductors and filters. This paper first reviews the thin-film characterization techniques for both piezoelectric and magnetostrictive thin films, which are crucial in determining the strength of the ME coupling. After that, the most recent progress on various integrated multiferroic devices based on thin-film ME heterostructures are presented. In particular, rapid development of thin-film ME magnetometers has been seen over the past few years. These ultra-sensitive magnetometers exhibit extremely low limit of detection (sub-pT/Hz1/2) for low-frequency AC magnetic fields, making them potential candidates for applications of medical diagnostics. Other devices reviewed in this paper include acoustically actuated nanomechanical ME antennas with miniaturized size by 1-2 orders compared to the conventional antenna; integrated RF tunable inductors with a wide operation frequency range; integrated RF tunable bandpass filter with dual H- and E-field tunability. All these integrated multiferroic devices are compact, lightweight, power-efficient, and potentially integrable with current complementary metal oxide semiconductor (CMOS) technology, showing great promise for applications in future biomedical, wireless communication, and reconfigurable electronic systems

Coupling of strain and magnetism in manganite-based complex oxide heterostructures

Complex oxide thin films and heterostructures offer a wide range of properties originating from the intrinsic coupling between lattice strain and magnetic/electronic ordering. This article reviews experimental, phenomenological, and theoretical analyses of the coupling of strain with electronic and magnetic properties of mixed valence manganite heterostructures. The influence of epitaxial strain on the magnetic properties of manganite films is measured using macroscopic magnetization measurements and shown mixed reports suggesting, both, an increase and decrease in ferromagnetic phases on the application of the strain. Using polarized neutron reflectivity (PNR), a simultaneous measurement of transport and magnetic properties of manganite thin films showed direct evidence of modification in the magnetic properties on the application of bending strain. The coupling coefficient of strain and magnetism of manganite heterostructures was estimated using PNR, which not only helped to understand the correlation of elastic strain with magnetism but also explained the condition of magnetic phase order change in the phase-separated systems within a phenomenological Ginzburg Landau theory. An overview is also provided of the current perspectives and existing studies on the influence of strain on structure, electronic, magnetic, magnetic anisotropy, phase coexistence and magnetocaloric properties of mixed valence manganite heterostructures. Based on the understanding of a diverse range of perovskite functionalities, detailed perspectives on how the coupling of strain and magnetism open up pathways toward the emergence of novel device design features including the different ways of applying uniform strain, are discussed.Comment: arXiv admin note: text overlap with arXiv:1509.00912, arXiv:1009.4548 by other author