T. Slupinski

Control of magnetization reversal process by light illumination in ferromagnetic semiconductor heterostructure p-(In, Mn)As/GaSb

The reduction in coercive force by light illumination has been found in ferromagnetic semiconductor heterostructure p-(In,u200aMn)As/GaSb prepared by molecular-beam epitaxy. Enhanced ferromagnetic coupling between Mn ions, arising from excess photogenerated holes, reduces the domain wall energy and changes the magnetization hysteresis characteristics. The value of coercive force returns to the original value when excess holes recombine with trapped electrons.

Ferromagnetic semiconductor (In, Ga, Mn)As with Curie temperature above 100 K

We have grown (InyGa1−y)1−xMnxAs ferromagnetic semiconductor layers with Mn composition of x up to 0.13 on InP substrates by molecular beam epitaxy. Near the lattice-matched composition, i.e., y∼0.53, the Curie temperature increases linearly with the ferromagnetically effective Mn composition xeff, following the empirical equation TC=1300×xeff. We obtained Curie temperatures above 100 K when x is relatively high (x>0.1;u200axeff⩾0.08) and the hole concentration is of the order of 1019u2009cm−3.

Preparation of ferromagnetic (In, Mn)As with relatively low hole concentration and Curie temperature 50 K

Abstract Ferromagnetic (In,Mn)As/GaSb and (In,Ga,Mn)As/GaSb heterostructures with Mn composition x =0.03–0.09 have been prepared by molecular beam epitaxy. It is found that the relation between maximum Curie temperature T C and Mn content x can be expressed experimentally by T C =800 x up to about T C =50xa0K within the limit of this study. The hole concentration sufficient for T C =50xa0K is found to be several times lower than the value shown in the existing theory (Science 287 (2000) 1049). Formation of structural pairs of Mn atoms (or few-atomic aggregates) in some close lattice sites is discussed to explain the observed results.

Effect of light illumination on the process of magnetization reversal in carrier-induced ferromagnetic semiconductors

Abstract We have found the reduction in coercive force by the light illumination for carrier-induced ferromagnetic semiconductor heterostructure p-(In,Mn)As/GaSb grown by molecular beam epitaxy. This effect disappears when the photogenerated holes recombine with trapped electrons. This strongly suggests that the observed phenomenon is attributed to the carrier-induced magnetism.

Manifestation of Local Magnetic Domain Reversal by Spin-Polarized Carrier Injection in (Ga,Mn)As Thin Films

Recently, we have reported that the spin-polarized holes generated by the irradiation with circularly polarized light can change the magnetization orientation of III–V ferromagnetic semiconductor (Ga,Mn)As via p–d exchange interaction. In this paper, we report that a small portion of change does not return to the initial state after the light is turned off. This residual component, named as the memorization effect, exhibits ferromagnetic characteristics. This fact strongly suggests that small magnetic domains having the perpendicular magnetic axis are rotated by photogenerated carrier spins.

Rotation of ferromagnetically coupled Mn spins in (Ga, Mn)As by hole spins

We present experimental data obtained from ferromagnetic p-(Ga,Mn)As layers that indicate the collective rotation of ferromagnetically coupled Mn spins by optically generated spin-polarized holes through the p–d exchange interaction. The rotation occurs reversibly between the in-plane and perpendicular directions, causing a large change in perpendicular magnetization without the application of a magnetic field. Pump-and-probe experiments suggest that the rotation of Mn spins take place in the picosecond time domain.

Preparation of ferromagnetic quaternary (In, Ga, Mn)As

Abstract We present preparation and magnetic properties of quaternary diluted magnetic semiconductor (In y Ga 1− y ) 1− x Mn x As epitaxial layers grown by molecular beam epitaxy (MBE). (In 0.53 Ga 0.47 ) 1− x Mn x As grown on InP substrates shows ferromagnetic order up to 60xa0K. Curie temperature shows linear dependence on effective Mn composition x eff , and can be expressed in the form: T C =1300 x eff .