Effects of superparamagnetism in MgO based magnetic tunnel junctions

被引：23
|
作者：
Shen, Weifeng [1 ,2 ]
Schrag, Benaiah D. [2 ]
Girdhar, Anuj [2 ]
Carter, Matthew J. [2 ]
Sang, Hai [3 ]
Xiao, Gang [1 ,3 ]
机构：
[1] Brown Univ, Dept Phys, Providence, RI 02912 USA
[2] Micro Magnet Inc, Fall River, MA 02720 USA
[3] Nanjing Univ, Dept Phys, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China
来源：
PHYSICAL REVIEW B | 2009年 / 79卷 / 01期
基金：
美国国家科学基金会; 中国国家自然科学基金;
关键词：
boron alloys; cobalt alloys; ferromagnetic materials; iron alloys; magnesium compounds; magnetic hysteresis; magnetic moments; magnetic multilayers; superparamagnetism; tunnelling magnetoresistance; ROOM-TEMPERATURE; MAGNETORESISTANCE; BEHAVIOR; GROWTH; FILMS; SHAPE;
D O I：
10.1103/PhysRevB.79.014418
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
We have investigated the magnetic and transport behavior of MgO based magnetic tunnel junctions incorporating Co40Fe40B20 free layers with thicknesses in the vicinity of 15 A. The magnetic response of the free layer changes rapidly as its thickness decreases. Linear and hysteresis-free switching is obtained when the CoFeB free layer thickness is thinner than a critical thickness of similar to 15 A. The tunneling magnetoresistance and hysteresis properties of the free layer change abruptly around the critical thickness. We have analyzed the transfer curves of junctions below the critical thickness and show that they agree well with the Langevin equation describing superparamagnetism. At even lower thicknesses, the total magnetic moment of the magnetic clusters decreases rapidly, possibly due to the reduction in the magnetic ordering temperature to below room temperature.
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页数：4
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