High Curie temperature and perpendicular magnetic anisotropy in homoepitaxial InMnAs films

Dilute ferromagnetic semiconductors such as III-Mn-V have lately attracted amount of attention, due to the considerable potential for spintronic device [1]. From the application point of view, the current-induced magnetization reversal originating from a spin transfer torque (STT) raises a special need for preparing DMS materials with a large perpendicular magnetic anisotropy (PMA) [2, 3]. The PMA in GaMnAs has been realized by two approaches: The mostly used one is to tune the strain from compressive to tensile state in GaMnAs either by applying InGaAs as buffer [2, 3]. Different from GaMnAs, homoepitaxial InMnAs on InAs is subject to tensile strain, therefore, should exhibit PMA. Moreover, ferromagnetic InMnAs films in principle provide a more suitable test-bed for STT phenomena in magnetic semiconductors due to its larger spin-orbit coupling [4]. We present the preparation of homoepitaxial InMnAs on InAs by ion implantation and pulsed laser melting. We show that a Curie temperature of 77 K (higher than reported up to now) is achieved in _In1-xMn_xAs with PMA at a Mn concentration of only x=0.08. The magnetic anisotropy in InMnAs is confirmed by magnetization and x-ray magnetic circular dichroism (XMCD) measurements. The pronounced PMA in this system is attributed to the tensile strain arising from the Mn ions incorporation.