[25a-E201-1~11] 10.3 Spin devices, magnetic memories and storages

△ [25a-E201-5] Investigation for TMR properties of MTJs using FeAlSi epitaxial films

〇(DC)Shoma Akamatsu¹, Mikihiko Oogane¹, Masakiyo Tsunoda¹, Yasuo Ando¹ (1.Tohoku Univ.)

Keywords:TMR effect, MTJ, Sendust

To improve the sensitivity of Magnetic tunnel junction (MTJ) sensors, there is a need for soft magnetic materials that have both a high tunnel magnetoresistance (TMR) ratio and soft magnetic properties. This study focused on Fe₈₅Al_5.4Si_9.6 (sendust, hereinafter referred to as FeAlSi), which exhibits excellent soft magnetic properties in the bulk state. Our previous study succeeded in fabricating D0₃-FeAlSi thin film on MgO substrate, which shows good soft magnetic properties. Since the crystal structure is similar to that of Fe electrodes, a high TMR ratio is also expected due to Δ1 coherent tunneling through the MgO barrier layer. This study aims to fabricate an MTJ device using FeAlSi single crystal thin film as a free layer and evaluate its TMR effect.
From the X-ray diffraction results of the FeAlSi thin film prepared under the optimum conditions, FeAlSi(004) and FeAlSi(002) peaks were observed, confirming the successful preparation of (001)-oriented FeAlSi thin film with B2-ordered structure. In addition, the TMR effect was successfully observed (121%, R.T.) with a low switching field because of the soft magnetic property of FeAlSi, although the TMR ratio degraded due to the oxidation of FeAlSi and MgO interface. The developed MTJs with a low switching field and high TMR ratio using the FeAlSi free layer are promising devices for MTJ-based magnetic sensors with high sensitivity.