TY - JOUR
T1 - Single layer of Mn in a GaAs quantum well
T2 - A ferromagnet with quantum fluctuations
AU - Melko, Roger G.
AU - Fishman, Randy S.
AU - Reboredo, Fernando A.
PY - 2007/3/14
Y1 - 2007/3/14
N2 - Some of the highest transition temperatures achieved for Mn-doped GaAs have been in δ -doped heterostructures with well-separated planes of Mn. In the absence of magnetic anisotropy, the Mermin-Wagner theorem implies that a single plane of magnetic ions cannot be ferromagnetic. Using a Heisenberg model, we show that the same mechanism that produces magnetic frustration and suppresses the transition temperature in bulk Mn-doped GaAs, due to the difference between the light and heavy band masses, can stabilize ferromagnetic order for a single layer of Mn in a GaAs quantum well. This comes at the price of quantum fluctuations that suppress the ordered moment from that of a fully saturated ferromagnet. By comparing the predictions of Heisenberg and Kohn-Luttinger models, we conclude that the Heisenberg description of a Mn-doped GaAs quantum well breaks down when the Mn concentration becomes large, but works quite well in the weak-coupling limit of small Mn concentrations. This comparison allows us to estimate the size of the quantum fluctuations in the quantum well.
AB - Some of the highest transition temperatures achieved for Mn-doped GaAs have been in δ -doped heterostructures with well-separated planes of Mn. In the absence of magnetic anisotropy, the Mermin-Wagner theorem implies that a single plane of magnetic ions cannot be ferromagnetic. Using a Heisenberg model, we show that the same mechanism that produces magnetic frustration and suppresses the transition temperature in bulk Mn-doped GaAs, due to the difference between the light and heavy band masses, can stabilize ferromagnetic order for a single layer of Mn in a GaAs quantum well. This comes at the price of quantum fluctuations that suppress the ordered moment from that of a fully saturated ferromagnet. By comparing the predictions of Heisenberg and Kohn-Luttinger models, we conclude that the Heisenberg description of a Mn-doped GaAs quantum well breaks down when the Mn concentration becomes large, but works quite well in the weak-coupling limit of small Mn concentrations. This comparison allows us to estimate the size of the quantum fluctuations in the quantum well.
UR - http://www.scopus.com/inward/record.url?scp=33947195291&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.75.115316
DO - 10.1103/PhysRevB.75.115316
M3 - Article
AN - SCOPUS:33947195291
SN - 1098-0121
VL - 75
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 11
M1 - 115316
ER -