Ferromagnetism in Mn doped copper oxide nanoflake like structures with high Neel temperature S. Ravi n , F. Winfred Shashikanth Department of Physics, Mepco Schlenk Engineering College, Sivakasi 626005, India article info Article history: Received 16 October 2014 Accepted 16 November 2014 Available online 26 November 2014 Keywords: Magnetic materials Semiconductors Dilute magnetic semiconductor (DMS) Mn:CuO Nanoflakes Magnetic oxide based semiconductors abstract Copper oxide is an excellent oxide based semiconductor with a wide bandgap and also a promising candidate for dilute magnetic semiconductor (DMS) when doped with some transition elements. We report 0.5% of manganese doped copper oxide based DMS with glycine as surfactant and surface assisting agent using a simple chemical route. The synthesized DMS material forms a nanoflake like structures and exhibit magnetic hysteresis at room temperature. At low temperature, the material exhibit weak hysteresis and exhibit antiferromagnetic ordering. This was explained on the basis of hopping mechanism. Low temperature magnetic study reveals Neel temperature of about 99 K, which is high for previously reported and can be a promising candidate for spintronic devices. & 2014 Elsevier B.V. All rights reserved. 1. Introduction The most interesting new magnetic materials to emerge in the last few years are a group of dilute ferromagnetic oxides and nitrides, which are wide-gap semiconductors with Curie tempera- tures well in excess of room temperature [1,2]. “Is it possible to create magnetic semiconductors that work at room temperature?” is the most common question in the scientific community. The answer is yes, but still there is difficult in explaining the nature or the origin of ferromagnetism in dilute magnetic semiconductors (DMS). Many semiconductors do possess ferromagnetism at room temperature, but the quest is wide-bandgap to be compatible in Opto-electronic devices. Copper oxide in nanostructure is one of the wide-gap semiconductors [3] with antiferromagnetic (AFM) ordering. This is an interesting material since CuO is associated with high tempera- ture superconductors. While there have been a few studies that have reported on Fe doped CuO [4–6], very few studies have examined Mn doped CuO [7]. In this context, we report a Mn doped CuO using a simple chemical route with glycine as fuel, which burns nitrates into oxides. The magnetic properties of this material are interesting with ferromagnetic response at room temperature and weak ferro- magnetic or AFM ordering at low temperature. We have also explained the magnetic behavior with the help of hopping mechan- ism of Mn 2 þ ions in Mn:CuO matrix. 2. Experimental The method adopted in the synthesis of Mn doped copper oxide is different from our earlier report for pure copper oxide [3], where we tuned the size by varying the concentration of L-cystine, which is used as surfactant and surface assisting agent. Here, we are not interested in the size distribution and hence use another interesting organic molecule glycine as fuel. Appropriate quantities of ultra pure Copper(II) nitrate (Cu(NO 3 ) 2 Á H 2 O) and 0.1% by weight of Manganese (II) nitrate (Mn(NO 3 ) 2 Á 4H 2 O) were mixed in a double deionized water for a homogenous solution. To this mixture 2 times by weight of glycine was added and 1 mmol of oleic acid was added drop wise, which acts as a surfactant and surface assisting agent. This mixture was stirred and heated simultaneously at the rate of 700 rpm and 10 1C/min respectively to the maximum of 240 1C. After 1 h, it forms a black precipitate and was collected. The black precipitate was centrifuged at the rate of 1200 rpm and kept at 300 1C in a vacuum oven overnight. This powder was finely grinded and preserved in the vacuum condition. 3. Results and discussion Fig. 1a shows the XRD pattern of as-synthesized Mn doped copper oxide nanoflakes. The pattern was indexed with the mono- clinic phase (C2/c) of copper oxide (JCPDS # 45-0937) and found to exist without any additional impurity. Weak peak at 30.31 is due the presence of CuMn 2 O 4 phase (JCPDS #84-0543) arises because of dilute doping of Mn ions in the CuO matrix. The prominent peak for this phase (35.81) overlaps with main CuO peak and hence it is not Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/matlet Materials Letters http://dx.doi.org/10.1016/j.matlet.2014.11.089 0167-577X/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ91 4562235690; fax: þ91 4562235111. E-mail address: sravi@mepcoeng.ac.in (S. Ravi). Materials Letters 141 (2015) 132–134