Influence of growth temperature on phase and intermixing in Ni 2 MnIn Heusler films on InAs(0 0 1) A. Zolotaryov a,Ã , A. Volland a , Ch. Heyn a , D. Novikov b , G. Stryganyuk b , A. Kornowski c , T. Vossmeyer c , O. Albrecht a , E. Coric d , W. Hansen a a Institute of Applied Physics, University of Hamburg, Jungiusstr.11, 20355 Hamburg, Germany b HASYLAB, DESY, Notkestr. 85, 22761 Hamburg, Germany c Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany d Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01219 Dresden, Germany article info Article history: Received 15 January 2009 Accepted 2 February 2009 Communicated by H. Asahi Available online 10 February 2009 PACS: 68.37.Àd 68.37.Lp 68.37.Ps 68.60.Dv 61.05.cm 61.05.cm Keywords: A1. Crystal structure A1. Interfaces A3. Molecular beam epitaxy B1. Nanomaterials B2. Magnetic materials B2. Semiconducting III–V materials abstract This paper reports on the influence of deposition temperature on structure and morphology of uncapped Ni 2 MnIn Heusler films grown by molecular beam epitaxy on InAs(0 0 1). Deposition temperatures between 80 and 360 1C and layer thicknesses between 20 and 100 nm have been used. Our studies reveal that during growth beyond 80 1C an intermixing layer arises at the Heusler/substrate interface that is formed by diffusion of arsenic from the substrate. The intermixing process, which is found to take place via interstitial sites, becomes increasingly severe with increasing growth temperature. Furthermore, we find that the films grown at 80 1C are polycrystalline with crystallites in the B2 phase. At 250 1C the films are found to be single-crystalline and pseudomorphically strained in the B2 phase. The desired L2 1 phase and single-crystalline Heusler films are observed at a growth temperature of 300 1C. Interestingly, Heusler films in L2 1 phase are found to have a (110) surface orientation in contrast to the InAs(0 0 1) substrate crystal. At temperatures higher than 300 1C, strong intermixing and a morphological degradation of the L2 1 Heusler films is observed. & 2009 Published by Elsevier B.V. 1. Introduction In the last decade there has been ongoing interest in hybrid structures made of metals and semiconductor heterostructures motivated by the proposal of novel spintronic devices based on the control of the spin orientation [1]. In some suggested spintronic devices magnetic metals serve as spin injecting and detecting electrodes and are combined with a semiconductor for spin manipulation [2]. In this field significant efforts were made to study the growth of various half-Heusler (e.g. NiMnSb [3–5]) and full-Heusler alloys (e.g. Ni 2 MnIn [6,7], Co 2 MnSi [8], Co 2 (Cr,Fe)Al [9]) on III–V semiconductor surfaces, such as GaAs(0 0 1), InAs (0 0 1) and InGaAs/InP(0 01). We investigate the growth of the full-Heusler alloy Ni 2 MnIn on InAs(0 01). This is motivated by the interesting transport properties of InAs compared for instance to GaAs and InP [10] such as a higher electron mobility and the absence of a Schottky barrier for evaporated metals. Furthermore, band structure calculations propose a high degree of spin– polarization of Ni 2 MnIn layers at the interface to InAs [11–14]. For the bulk lattice constant of a cubic Ni 2 MnIn unit cell two different values are reported in literature: 0.6024 and 0.6069 nm, which are still under discussion [15,16]. Nevertheless, both values would allow epitaxial growth of Ni 2 MnIn/InAs(0 0 1) hybrid structures with a lattice mismatch of less then 0.2%. It is known that the process parameters during Ni 2 MnIn deposition strongly influence the structural and magnetic properties of the resulting films [7,17]. In particular, the formation of two main cubic phases (L2 1 and B2) was reported for Ni 2 MnIn, which possess strongly different magnetic properties. Furthermore, the possibility of chemical reactions at the interface between the Heusler deposit and the III–V compound is known [18]. The occurrence of interfacial reactions and a corresponding intermixed layer for ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jcrysgro Journal of Crystal Growth 0022-0248/$ - see front matter & 2009 Published by Elsevier B.V. doi:10.1016/j.jcrysgro.2009.02.001 Ã Corresponding author. E-mail address: azolotar@physnet.uni-hamburg.de (A. Zolotaryov). Journal of Crystal Growth 311 (2009) 2397–2404