Effect of capping superconductive layer and MgO spacer ontunnel magnetoresistance

• Main Authors: Bin-Chan Lin, 林炳全
• Other Authors: Minn-Tsong Lin
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/80787272796198411497

碩士 === 國立臺灣大學 === 物理研究所 === 95 === Magnetic tunnel junction is a promising candidate for applications in magnetic-storage technology, such as non-volatile memory, read head and magnetic sensors. Much higher tunnel magnetoresistance and lower resistance of junctions provide the feasibility for high-density magnetoresistive random-access-memory (MRAM) and less power consumption. We investgated the influence upon structure of magnetic tunnel junctions, including added capping layer and modification of spacer. We found that the TMR ratio drastically decreased with capping superconductive Nb. The thickness of capping Nb layer was varied onto TMR junctions to investgate the relation between superconductor and magnetism. Another TMR structure was examined on altering spacer. Huge TMR values have been theoretically predicted in (100) oriented single-crystalline Fe/MgO/Fe MTJs. We have fabricated MgO barrier layer which was sandwiched with amorphous CoFeB electrodes by magnetron supttering. We exhibit a well-defined parallel/antiparallel magnetic configuration by invoking Magneto-Optical Kerr Effect(MOKE), and adjust the thickness of MgO barrier to optimize TMR ratio. The annealing effect was also investigated to promote TMR value.