[14p-K302-1~14] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

16:00 〜 16:15英語発表

[14p-K302-10] Microscopic study of MTJ degradation toward High-density STT-MRAM: Impact of interface Oxygen Frenkel defects in MgO barrier

〇Rina Takashima¹, Takeo Koike¹, Shogo Itai¹, Hideyuki Sugiyama¹, Young Min Lee¹, Masaru Toko¹, Soichiro Ono¹, Daisuke Watanabe¹, Soichi Oikawa¹, Katsuhiko Koi¹, Hiroyuki Kanaya¹, Kohji Nakamura², Masahiko Nakayama¹ (1.Kioxia Corporation, 2.Mie Univ.)

キーワード：

MTJ、MRAM、ab initio calculation

We experimentally observed the resistance drift and TMR ratio degradation under a voltage stress in MTJs with a diameter of 25 nm. We investigated the mechanism behind these phenomena and proposed methods to suppress them using density functional theory, nonequilibrium Green function calculations, and a time-evolution model. Through microscopic calculations, we found that the degradation can be explained by current-induced generation of oxygen Frenkel defects at the interface of MgO and Fe. It was found that the initial oxygen vacancies at the interface of MgO lower the formation energy of interface O Frenkel defect. Therefore, the reduction in the initial oxygen vacancies suppresses the resistance drift and TMR degradation by mitigating the generation of Frenkel defects.