Zhou et al. Nanoscale Research Letters 2011, 6:276 http://www.nanoscalereslett.com/content/6/1/276 Page 3 of 6 Figure 2 FE-SEM images of the cross section of Co/InP nanocomposite structure with different deposition times of Co: (a) 0 s, (b) 30 s, (c) 90 s, and (d) 5 min. article; similar studies in porous silicon matrix have been summarized by Ogata et al. [41]. It is also noted that there is oxygen in the first pro- duct prepared by electrodeposition in aqueous solution of cobalt chloride under same conditions (this EDS spectrum is not illustrated in this article), which indi- cates that Co has been oxidized. Therefore, ethanol solution is chosen to fabricate Co/InP nanocomposites, the composition of which is analyzed by EDS as shown in Figure 3a, where only In, P, and Co exist (without the presence of oxygen), indicating that the pure Co nano- particles have been successfully embedded in the porous InP semiconductor matrix and the ethanol solution effectively protects Co from oxidization. To further investigate the structure and composition of such Co/ InP nanocomposites, the XRD pattern has been mea- sured and shown in Figure 3b, where two strong diffrac- tion peaks at 2θ = 30.52° and 63.41° are, respectively, identified as (200) and (400) of the porous InP template consistent with the previous results [34,40]. The other four peaks at 2θ = 41.59°, 44.26°, 47.39°, and 75.89° correspond to hexagonal Co (100), (002), (101), and (110), respectively. This further confirms that the obtained sample is that of Co/InP nanocomposites. Magnetic properties of Co/InP nanocomposites Figure 4 shows field-dependent magnetization (M-H) curves of such Co/InP nanocomposites, where the applied magnetic field is perpendicular to the surface of the InP template or parallel to the axis of InP channel. For the deposition time of 30 s, the Co/InP nanocompo- site presents diamagnetism as shown in Figure 4a, which is ascribed to the complete diamagnetism of n-type por- ous InP template according to the above SEM analysis and the M-H curve of pure InP (Figure 4b). While weak ferromagnetism is detected for the sample with the deposition time of 90 s (Figure 4a), with the deposition time of 5 min, the Co/InP nanocomposite exhibits visible hysteresis loop as shown in Figure 4b. This indicates that the Co particles embedded in the InP matrix dominate the magnetic behavior of this Co/InP nanocomposite when the content of Co gradually increases due to the