Abstract:
The key to integrating the concepts of spintronics into modern electronics ties with the ability to control the magnetic order in nanoscale devices. With the continuous shrinkage of integrated circuits, the energy efficiency required to control these tiny magnets as power dissipation becomes a determining factor for the advanced process node. Over the past decades, the oxide community has been exploring the materials that can provide opportunities to control magnetism. Among the large investigated materials, multiferroics might be one of the most promising material family. Multiferroics are defined as the materials which possess at least two order of parameters, particularly, the coexistence of ferroelectricity (P) and magnetism (M), and exhibit coupling from one to another. In this talk, I will discuss the magnetoelectric switching mechanism in lanthanum-doped BiFeO3 thin films. BiFeO3 is by far the best-studied multiferroic, which shows strong ferroelectricity (~100 µC/cm2) and G-type antiferromagnetism, above room temperature. It also shows weak ferromagnetism (MC) induced by the canted spin configuration described by the Dzyaloshinskii–Moriya interaction (DMI). Moreover, these ferroic orderings, P and MC, are strongly coupled, thus one can switch the magnetism by an electric field. However, the strong
spontaneous polarization in BiFeO3 needs a large driven voltage. Here, we introduce the chemical doping to modify the order parameters in BiFeO3 and achieve an ultralow-voltage (< 500 mV) and non-volatile manipulation of ferromagnetism at room temperature. Moreover, while the lanthanum-doping increased, we observed a very different magnetoelectric switching pathway and magnetic anisotropy compare to pure BFO. This discovery leads to the enhancement of perpendicular magnetic anisotropy (PMA) on multiferroics thin film, which will be very attractive to the practical applications. Finally, I will conclude this talk with a summary of current challenges and future direction of multiferroics, especially BiFeO3, toward the low-power electronics.
Keywords – Multiferroics, thin-film, XMLD