Crossing a Ferroelectric Tunnel Barrier

Abstract: For several decades, ferroelectricity has been in the mainstream of modern researches as it has attracted large attention of a number of researchers in various research fields such as physics, chemistry, materials science, and electrical engineering. Although ferroelectricity itself has been vigorously studied for a long time, the subject keeps attracting attention as several ferroelectricity-related new phenomena have been recently discovered, which are very interesting from scientific as well as technical perspectives. 1 One of them is the strong effect of ferroelectricity on the electron/spin transport properties of ferroelectric (FTJs)/multiferroic (MFTJs) tunnel junctions. 1 From a technical perspective, FTJ/MFTJs are of significant importance as they potentially work as memory elements in resistance-based future nonvolatile memories. Despite recent advances in experimental and theoretical studies of FTJs/MFTJs, a substantial number of questions concerning their electrical behavior still remain open, e.g. the effect of an electrode material and the role of inherent (microstructural/chemical) asymmetry at the interfaces of the junction on the FTJs/MFTJs properties. In this talk, after a brief introduction and an overview of my research activities, I will present my recent results on FTJs and MFTJs. First, I'll show that effects from ferroelectric-electrode interfaces can have a strong impact on the tunneling electroresistance (TER) properties of asymmetric, LSMO/BTO/Au(Cu), FTJs. 2 After that, from my study on epitaxial, LSMO/PZT/LSMO, MFTJs that are nominally symmetric, I'll show that the inherent asymmetry in the MFTJ (arising from the microstructural and chemical asymmetry at the interfaces) likely suffices to drive the intertwined TER and TMR effects. 3 In addition, the tunnel magnetoresistance reversal on polarization switching will be shown in such MFTJs. 4

References:

1. E. Y. Tsymbal et al. Science 313, 181–183 (2006).

2. R. Soni et al., Nature Communications 5, 5414 (2014).

3. R. Soni et al., Nanoscale 8, 10799 (2016).

4. R. Soni et al. (manuscript in preparation)

Venue: Departmental Library, Physics Department (second floor) IIT Bombay, Powai, Mumbai