[11p-W351-1~14] 6.1 Ferroelectric thin films

[11p-W351-5] Ferroelectric capacitors with a controlled oxygen-vacancy distribution

〇Yuji Noguchi¹, Hiroki Matsuo², Masaru Miyayama¹ (1.Univ. Tokyo (SOE), 2.Univ. Tokyo (GSFS))

Keywords:ferroelectric, point defect, oxygen vacancy

Controlling defects in materials provides an extra degree of freedom not only for enhancing properties but also for introducing additional functionalities. In ferroelectric oxides, an accumulation of point defects at boundaries often deteriorates a polarization-switching capability, but on the one hand, delivers interface-driven phenomena. Despite several decades of intensive research, it remains challenging to manipulate oxygen vacancies to result in a desirable defect structure. Here, we report a practical route to designing oxygen-vacancy distributions by utilizing the interaction with transition-metal dopants. Our thin-film experiments combined with ab-initio theoretical calculations for BiFeO₃ demonstrate that isovalent dopants such as Mn³⁺ with a partly or fully electron-occupied e_g state can trap oxygen vacancies, leading to a complete polarization switching. Our approach to controlling point defects will offer an ability to harness the full potential of switchable polarization and also of domain-wall functions in ferroelectric devices.