TY - JOUR
T1 - Curie temperature limit in ferromagnetic Ga1-xMnxAs
AU - Yu, K. M.
AU - Walukiewicz, W.
AU - Wojtowicz, T.
AU - Lim, W. L.
AU - Liu, X.
AU - Bindley, U.
AU - Dobrowolska, M.
AU - Furdyna, J. K.
PY - 2003/7
Y1 - 2003/7
N2 - We provide experimental evidence that the upper limit of ∼110 K commonly observed for the Curie temperature TC of Ga 1-xMnxAs thin films (thickness >50 nm) is caused by Fermi-level-induced hole saturation. Ion channeling, electrical, and magnetization measurements on a series of Ga1-x-yMn xBeyAs layers show a dramatic increase of the concentration of Mn interstitials accompanied by a reduction of TC with increasing Be concentration, while the free hole concentration remains relatively constant at ∼5 × 1020 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.
AB - We provide experimental evidence that the upper limit of ∼110 K commonly observed for the Curie temperature TC of Ga 1-xMnxAs thin films (thickness >50 nm) is caused by Fermi-level-induced hole saturation. Ion channeling, electrical, and magnetization measurements on a series of Ga1-x-yMn xBeyAs layers show a dramatic increase of the concentration of Mn interstitials accompanied by a reduction of TC with increasing Be concentration, while the free hole concentration remains relatively constant at ∼5 × 1020 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.
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U2 - 10.1103/PhysRevB.68.041308
DO - 10.1103/PhysRevB.68.041308
M3 - RGC 22 - Publication in policy or professional journal
SN - 0163-1829
VL - 68
SP - 413081
EP - 413084
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 4
M1 - 41308
ER -