Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers.
Magnetically engineered magnetic tunnel junctions (MTJs) show promise as non-volatile storage cells in high-performance solid-state magnetic random access memories (MRAM). The performance of these devices is currently limited by the modest (< approximately 70%) room-temperature tunnelling magnetoresistance (TMR) of technologically relevant MTJs. Much higher TMR values have been theoretically predicted for perfectly ordered (100) oriented single-crystalline Fe/MgO/Fe MTJs. Here we show that sputter-deposited polycrystalline MTJs grown on an amorphous underlayer, but with highly oriented (100) MgO tunnel barriers and CoFe electrodes, exhibit TMR values of up to approximately 220% at room temperature and approximately 300% at low temperatures. Consistent with these high TMR values, superconducting tunnelling spectroscopy experiments indicate that the tunnelling current has a very high spin polarization of approximately 85%, which rivals that previously observed only using half-metallic ferromagnets. Such high values of spin polarization and TMR in readily manufactureable and highly thermally stable devices (up to 400 degrees C) will accelerate the development of new families of spintronic devices.
Parkin
Stuart S P
SS
IBM Research Division, IBM Almaden Research Center, IBM-Infineon MRAM Development Alliance, 650 Harry Road, San Jose, California 95120, USA. parkin@almaden.ibm.com
Kaiser
Christian
C
Panchula
Alex
A
Rice
Philip M
PM
Hughes
Brian
B
Samant
Mahesh
M
Yang
See-Hun
SH
D003201:Computers; D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D004566:Electrodes; D004581:Electronics / Q000295:instrumentation*; D004867:Equipment Design; D016247:Information Storage and Retrieval / Q000379:methods*; D008277:Magnesium Oxide / Q000737:chemistry*; D008280:Magnetics / Q000295:instrumentation*; D008420:Manufactured Materials; D008422:Materials Testing; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013696:Temperature
D008277:Magnesium Oxide