Curie temperature limit in ferromagnetic Ga1-xMnxAs
Curie temperature limit in ferromagnetic Ga1-xMnxAs
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DOI：
10.1103/physrevb.68.041308
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发表时间：
2003-03
影响因子：
3.7
通讯作者：
K. Yu;W. Walukiewicz;T. Wojtowicz;W. Lim;X. Liu;U. Bindley;M. Dobrowolska;J. Furdyna
中科院分区：
文献类型：
--
作者：
K. Yu;W. Walukiewicz;T. Wojtowicz;W. Lim;X. Liu;U. Bindley;M. Dobrowolska;J. Furdyna
实验结果表明，Ga 1 -xMnxAs薄膜（厚度>50 nm）居里温度T C的上限为110 K，这是由费米能级诱导空穴饱和引起的.对一系列Ga 1 -x-yMnxBeyAs层的离子沟道、电学和磁化强度的测量表明，随着Be浓度的增加，Mn的浓度急剧增加，同时Tc降低，而自由空穴浓度保持相对恒定，约为1.5 × 1020 cm - 3 .这些结果表明，自由空穴和铁磁活性Mn自旋的浓度取决于费米能级的位置，费米能级控制补偿间隙Mn施主的形成能量。
We provide experimental evidence that the upper limit of ∼110 K commonly observed for the Curie temperature T C of Ga 1 - x Mn x As thin films (thickness >50 nm) is caused by Fermi-level-induced hole saturation. Ion channeling, electrical, and magnetization measurements on a series of Ga 1 - x - y Mn x Be y As layers show a dramatic increase of the concentration of Mn interstitials accompanied by a reduction of T C with increasing Be concentration, while the free hole concentration remains relatively constant at ∼5 X 10 2 0 cm - 3 . These results indicate that the concentrations of free holes and ferromagnetically active Mn spins are governed by the position of the Fermi level, which controls the formation energy of compensating interstitial Mn donors.