The influence of impurities within the barrier on tunneling magnetoresistance
The influence of impurities within the barrier on tunneling magnetoresistance
复制标题
势垒内杂质对隧道磁阻的影响
DOI：
--
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
D. Pettifor
中科院分区：
文献类型：
--
作者：
E. Tsymbal;D. Pettifor
在单带紧束缚模型下，计算了铁磁隧道结中金属杂质和势垒层无序的隧穿磁电阻（TMR）。我们发现，引入的杂质，其具有接近费米能级的现场原子能量导致TMR作为杂质浓度的函数的快速下降。这是由于接近费米能的局部电子能级的数量增加，这促进了绝缘体内高导电沟道的形成。随着杂质原子能的增加，通过杂质带的隧穿导致较高的TMR值，这是由于与这种隧穿机制相关的较高的有效势垒。在这种情况下，在势垒内引入杂质可以提供增强的电导值，而不会显著降低隧道结的MRAM应用所需的TMR。
Tunneling magnetoresistance (TMR) of a ferromagnetic tunnel junction is calculated in the presence of nonmagnetic metal impurities and disorder in the barrier layer within a single-band tight-binding model. We found that the introduction of impurities which have onsite atomic energies close to the Fermi level leads to a rapid drop in TMR as a function of the impurity concentration. This results from the increasing number of localized electronic levels close to the Fermi energy which promote the formation of highly conducting channels within the insulator. With increasing atomic energy of the impurities, tunneling via the impurity band results in higher values of TMR due to a higher effective potential barrier associated with this mechanism of tunneling. In this case introduction of impurities within the barrier can provide enhanced values of conductance without a significant reduction in TMR, which is required for MRAM applications of tunnel junctions.