Applied Surface Science 257 (2011) 10557–10561 Contents lists available at ScienceDirect Applied Surface Science j our nal ho me p age: www.elsevier.com/loc ate/apsusc Structural, magnetic and electronic structure studies of Mn doped TiO 2 thin films Shalendra Kumar a,∗ , S. Gautam b , G.W. Kim a , Faheem Ahmed a , M.S. Anwar a , K.H. Chae b , H.K. Choi a , H. Chung c , B.H. Koo a,∗ a School of Nano and Advanced Materials Engineering, Changwon National University, 9 Sarim dong, Changwon 641-773, Republic of Korea b Nano Analysis Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea c Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cooling Energy Mechanical Research Team, Gyeongsang National University, Tongyeong 650-160, Republic of Korea a r t i c l e i n f o Article history: Received 23 March 2011 Received in revised form 11 July 2011 Accepted 11 July 2011 Available online 2 August 2011 Keywords: TiO2 XRD Magnetization NEXAFS DMS XMCD a b s t r a c t We report structural, magnetic and electronic structure study of Mn doped TiO 2 thin films grown using pulsed laser deposition method. The films were characterized using X-ray diffraction (XRD), dc mag- netization, X-ray magnetic circular dichroism (XMCD) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements. XRD results indicate that films exhibit single phase nature with rutile structure and exclude the secondary phase related to Mn metal cluster or any oxide phase of Mn. Magnetization studies reveal that both the films (3% and 5% Mn doped TiO 2 ) exhibit room temperature ferromagnetism and saturation magnetization increases with increase in concentration of Mn doping. The spectral features of XMCD at Mn L 3,2 edge show that Mn 2+ ions contribute to the ferromagnetism. NEXAFS spectra measured at O K edge show a strong hybridization between Mn, Ti 3d and O 2p orbitals. NEXAFS spectra measured at Mn and Ti L 3,2 edge show that Mn exist in +2 valence state, whereas, Ti is in +4 state in Mn doped TiO 2 films. © 2011 Elsevier B.V. All rights reserved. 1. Introduction In the recent years, oxide based dilute magnetic semiconduc- tors (DMSs) with room temperature ferromagnetism (RTFM) have been intensively studied due to their remarkable properties and potential applications in spintronics devices such as spin light emit- ting diodes (spin LEDs), spin field effect transistors (spin FET) and spin qubits for quantum computers, etc. [1,2]. However, in spite of lot of work done on DMSs, the understanding of the origin of RTFM in undoped and transition metal (TM) doped wide band gap semiconductors, such as: ZnO, In 2 O 3 , CeO 2 SnO 2 , TiO 2 etc. [3–11], remains one of the most important challenge in the condensed mat- ter physics and physics of magnetism. Moreover, after the discovery of RTFM in Co doped anatase TiO 2 thin film [12], extensive investi- gations have been done on the synthesis and magnetic properties of transition metal doped TiO 2 based DMSs. However, the FM has been observed in various TiO 2 based DMSs above room temperature, but the origin of FM is still a controversial issue. Some studies suggest that the FM originates from the presence of secondary phase or fer- romagnetic clusters, whereas other results indicate the existence of intrinsic FM of TM substitution in TiO 2 lattice. Wang et al. [13] and ∗ Corresponding authors. E-mail addresses: shailuphy@gmail.com (S. Kumar), bhkoo@changwon.ac.kr (B.H. Koo). Xu et al. [14] reported RTFM in Mn doped TiO 2 and attributed its origin to be intrinsic. These groups explained that FM result due to the coupling between the Mn magnetic moment via large concen- tration of holes, whereas, Hong et al. [15] argued that Mn doping did not play any role in inducing the FM. Therefore, more intensive and extensive study is essential, as mechanism in TiO 2 based DMSs is still far from being well understood. In the present work, we have deposited Mn doped TiO 2 thin films using pulsed laser depo- sition method and then investigated their structural, magnetic and electronic structural properties using various techniques such as: X-ray diffraction (XRD), dc magnetization, X-ray magnetic circular dichroism (XMCD) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements. XRD results show the single phase nature of the films and ruled out the possibility of impurity phase. Field cooled magnetization and magnetic hysteresis loop studies infer that the Mn doped TiO 2 films show the RTFM. XMCD result indicates that Mn 2+ ions contribute to the RTFM. NEXAFS studies indicate the strong hybridization between Mn 3d and O 2p orbitals and show that Mn and Ti exist in +2 and +4 valence state, respectively. 2. Experimental conditions We grew thin films of Mn doped TiO 2 by using pulsed laser depo- sition (PLD) method. Targets of Mn doped TiO 2 were prepared using a conventional solid state reaction method. The stoichiometric 0169-4332/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2011.07.050