1202.1915 (M. A. Pankov et al.)

Pecularities of Hall effect in
GaAs/δ/GaAs/In\timesGa1-\timesAs/GaAs (\times {\approx} 0.2)
heterostructures with high Mn content    [PDF]

M. A. Pankov, B. A. Aronzon, V. V. Rylkov, A. B. Davydov, V. V. Tugushev, S. Caprara, I. A. Likhachev, E. M. Pashaev, M. A. Chuev, E. Lähderanta, A. S. Vedeneev, A. S. Bugaev

Transport properties of GaAs/{\delta}/GaAs/In\timesGa1-\timesAs/GaAs
structures containing InxGa1-xAs (\times {\approx} 0.2) quantum well (QW) and
Mn delta layer (DL) with relatively high, about one Mn monolayer (ML) content,
are studied. In these structures DL is separated from QW by GaAs spacer with
the thickness ds = 2-5 nm. All structures possess a dielectric character of
conductivity and demonstrate a maximum in the resistance temperature dependence
Rxx(T) at the temperature {\approx} 46K which is usually associated with the
Curie temperature Tc of ferromagnetic (FM) transition in DL. However, it is
found that the Hall effect concentration of holes pH in QW does not decrease
below TC as one ordinary expects in similar systems. On the contrary, the
dependence pH(T) experiences a minimum at T = 80-100 K depending on the spacer
thickness, then increases at low temperatures more strongly than ds is smaller
and reaches a giant value pH = (1-2)\cdot10^13 cm^(-2). Obtained results are
interpreted in the terms of magnetic proximity effect of DL on QW, leading to
induce spin polarization of the holes in QW. Strong structural and magnetic
disorder in DL and QW, leading to the phase segregation in them is taken into
consideration. The high pH value is explained as a result of compensation of
the positive sign normal Hall effect component by the negative sign anomalous
Hall effect component.

View original: http://arxiv.org/abs/1202.1915