Toward electrically controllable read

Magneto-resistive memory in cross-like (Ga,Mn)As nanostructures
T. Andrearczyk 1, I. Krogulec 1,2, T. Wosiński 1, T. Figielski 1, A. Mąkosa 1, J. Wróbel 1 and
J. Sadowski 1,3
1
2
Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland
College of Science, Cardinal S. Wyszynski University, 01-815 Warsaw, Poland
3
MAX-Lab, Lund University, 22100 Lund, Sweden
We present our results [14] of magnetoresistance (MR) measurements carried out for crosslike nanostructures fabricated from p-type Ga0.94Mn0.06As ferromagnetic film, that is 20 nm
thick. The nanostructures’ pattern, as prepared by electron-beam lithography technique,
consists of two perpendicularly crossed nanowires, each of them having about 200 nm width
and 2 µm length. The MR of such nanostructures exhibits the hysteresis-like behaviour and
related remnant resistance effect in zero magnetic field, which has been explained as due to
contribution of the magnetic domain walls (DWs) pinned at the intersection of the nanowires.
Basically, we show here an effect of DWs’ magnetic angle on the remnant resistance of the
nanowires, observed in regime of relatively low magnetic fields up to 100 Oe. We fabricated
a series of the cross-like nanostructures tilted by different angles: 0, 20 and 45 deg, with
respect to the 100 crystallographic axes. A pronounced enhancement of the DWs’
contribution to the resistance was observed for the 20 deg. Additionally, we show the MR
results in higher field range, up to 1 kOe, which allowed us for determining so called
lithography-induced anisotropy field. Its value, although depending on the tilt angle, is much
higher than the in-plane magnetic anisotropy field of the (Ga,Mn)As film, thus indicating the
DWs pinning mechanism as resulting from the competition between two anisotropies: the
magneto-crystalline and the lithography-induced one. We also discuss the contribution of
anisotropic magneto-resistance to the observed magneto-resistive memory effect and interpret
the effect in terms of DWs rearrangement in the nanostructures.
This work has been partially supported by the Polish Ministry of Science and Higher
Education under Grant No. N N202 129339.
[1] T. Andrearczyk, T. Wosinski, T. Figielski, A. Makosa, I. Krogulec, J. Wróbel, and J.
Sadowski, Phys. Status Solidi B 248, 1587 (2011).
[2] T. Andrearczyk, T. Wosiński, A. Mąkosa, T. Figielski, J. Wróbel, and J. Sadowski, Acta
Phys. Pol. A 116, 901 (2009).
[3] T. Andrearczyk, T. Wosiński, T. Figielski, A. Mąkosa, J. Sadowski, Z. Tkaczyk, E.
Łusakowska, and J. Wróbel, Acta Phys. Pol. A 114, 1049 (2008).
[4] T. Figielski, T. Wosiński, A. Morawski, A. Mąkosa, J. Wróbel, and J. Sadowski, Appl.
Phys. Lett. 90, 052108 (2007).