Improvement of thermal stability of nano-granular TMR films by using a Mg-Al-O insulator matrix

• Published in: AIP advances Vol. 8; no. 5; pp. 056313 - 056313-6
• Main Authors: Kanie, S., Koyama, S.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01.05.2018; AIP Publishing LLC
• Subjects: Aluminum; Annealing; Cobalt; Crystal structure; Insulators; Iron; Magnesium; Magnetoresistance; Magnetoresistivity; Thermal stability
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/1.5005138

A new metal-insulator nano-granular tunneling magnetoresistance (TMR) film made of (Fe-Co)-(Mg-Al-O) has been investigated. It is confirmed that the film has granular structure in which crystal Fe-Co granules are surrounded by an amorphous Mg-Al-O matrix. A large MR ratio of 11.8 % at room temperature is observed for a 42 vol.%(Fe0.6Co0.4)-(Mg-Al-O) film annealed at 395 °C. The electrical resistivity increases rapidly by annealing at above the changing point (500 °C). The changing point is about 300 °C higher than that of conventional (Fe-Co)-(Mg-F) nano-granular TMR films. The 42 vol.%(Fe0.6Co0.4)-(Mg-Al-O) film also exhibits less degradation in the MR ratio at high annealing temperatures such as 600 °C. These results suggest the (Fe-Co)-(Mg-Al-O) film is superior to the (Fe-Co)-(Mg-F) film in thermal stability.