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(Inserted by IEEE.) 1 Ferromagnetism of nanographite structures in carbon microspheres Eduard Sharoyan 1 , Armen Mirzakhanyan 1 , Harutyun Gyulasaryan 1 , Carlos Sanchez 2 , Armen Kocharian 2 , Oscar Bernal 2 and Aram Manukyan 1 1 Institute for Physical Research, National Academy of Sciences, 0203, Ashtarak, Armenia 2 Department of Physics, California State University, Los Angeles, USA Carbon microspheres with unusual magnetic properties have been prepared by method of solid-phase pyrolysis where metal-free phthalocyanine was used as a precursor. The morphology, structure and magnetic properties of prepared samples were investigated using electron microscopy, magnetometry and electron paramagnetic resonance. Carbon microspheres with a mean diameter d = 3.40±0.15 μm consist of graphitized nanocrystallites with a thickness of 5-15 graphene layers. The samples demonstrate a strong paramagnetism with the concentration of paramagnetic centers ~ 5×10 19 spin/g. In the temperature range of 5-100 K a ferromagnetism was revealed with a maximum value of the saturation magnetization, M s ≈ 0.03 emu/g at Т= 25К. The temperature-independent diamagnetism with susceptibility of χ Dia = -1∙10 -6 emu/g∙Oe was also measured. Index Terms— carbon ferromagnetism, nanographite, phthalocyanine, solid-phase pyrolysis. I. INTRODUCTION n recent years, carbon magnetism attracted great interest from the point of view of both fundamental science and practical applications [1-3]. Search of magnetism based on light elements is of great importance, since these materials have a number of advantages: low density, biocompatibility, plasticity, transparency, etc. Among these elements carbon takes a specific place, especially after discovery of its novel nanoscopic modifications such as graphene, fullerenes, nanotubes and nanocapsules, nanographene ribbons, etc. Transition from macroscopic sizes to nanoscopic ones can be very radical and may help to create new unique novel materials and devices. For instance, when the sizes of nanographites or nanographene are decreased to a few nanometers, the role of edge states with “zigzag” and “armchair” shapes in their electronic structure strongly increases. In edge states of zigzag-type the π-electrons are localized and strongly spin-polarized, which influences also the transport properties of electrons. Unusual magnetic and electronic properties of nanographite and nanographene are not only the manifestation of novel properties in the physics of condensed state but also an attractive area for potential applications in electronics, spintronics, quantum information processing, etc. [2,3]. In nanographites and nanographene not only edge states can play an essential role in appearance of magnetic and transport properties. Different defects such as vacancies, topological defects and doping with different elements and functional groups can also play a key role [3]. Defects in graphite/graphene lattices were introduced by various methods: intercalation of atoms and molecules, doping, proton irradiation, carbon implantation, etc [1,3,4]. Defect atoms (for instance, vacancies, substitution of carbon by nitrogen or hydrogen chemisorption) induce spin-polarized defect states [2,5]. Among experimental works, related to the “defect” carbon magnetism caused by vacancies, one can mention [4], where a room-temperature ferromagnetism was observed in highly oriented pyrolytic graphite (HOPG) irradiated with high- energy (2.25 MeV) protons. Among a large number of theoretical works in the field of carbon magnetism, one can underline the work [6] where a ferromagnetic Stoner criterion in narrow impurity bands for sp-electrons was derived and a possible realization of high-temperature ferromagnetism at relatively low electron concentrations was shown. In [7,8] by solid-phase pyrolysis of metal-free phthalocyanine (H 2 Pc) ≡ H 2 (C 32 N 8 H 16 ) a carbon microspheres were obtained with an average diameter of about 3 μm, consisting of nanographite structures and exhibiting an intense electron paramagnetic resonance (EPR) signal. With a view to more in-depth study of the magnetic characteristics of the prepared microspheres in the present study we carried out magnetometer measurements in the temperature range of 10 K-300 K. II. EXPERIMENTAL TECHNIQUE For preparation of metal nanoparticles and nanoalloys, we developed a method of solid-phase pyrolysis in organic and organometallic compounds, as described in [8.9]. The advantage of this method: it is a single-stage, rather simple and provides a high yield of the final product. Previously using this technique we obtained various nanocomposites Ni/C, Cu/C, and nanoalloys Ni 1-x Cu x in different carbon matrices [9-11]. In this paper, pre-purified polycrystalline powders H 2 Pc in a quartz ampoule with a volume ≈100 cm3 were sealed in a vacuum of ~10 -6 MPa. The rapid heating of samples to temperatures above the 600⁰C results in thermal decomposition of H 2 Pc molecules according to reaction p p 2 2 , , 2 32 8 16 -9H ,-4N H (C N H ) 32 C , p T t P  (1) where T p - pyrolysis temperature, t p – time of pyrolysis, P p – self-generated gas pressure in the ampoule. We selected I