Electronic structure and magnetic properties of Ni-doped SnO2 thin films Mayuri Sharma, Shalendra Kumar, and P. A. Alvi
Citation: AIP Conference Proceedings 1953, 120010 (2018); doi: 10.1063/1.5033075 View online: https://doi.org/10.1063/1.5033075 View Table of Contents: http://aip.scitation.org/toc/apc/1953/1 Published by the American Institute of Physics
Articles you may be interested in Structural, magnetic and electronic structural properties of Mn doped CeO2 nanoparticles AIP Conference Proceedings 1953, 120038 (2018); 10.1063/1.5033103 Structural and Mössbauer analysis of pure and Ce-Dy doped cobalt ferrite nanoparticles AIP Conference Proceedings 1953, 120046 (2018); 10.1063/1.5033111 Enhanced room temperature ferromagnetism in Ni doped SnO2 nanoparticles: A comprehensive study Journal of Applied Physics 122, 083906 (2017); 10.1063/1.4999830
Electronic Structure and Magnetic Properties of Ni-doped SnO2 Thin Films Mayuri Sharmaa, Shalendra Kumarb*, and P. A. Alvia* a
Department of Physics, Banasthali University, Banasthali-304022, Rajasthan (INDIA) b Department of Applied Physics, Amity School of Applied Sciences, Amity University Haryana, Gurgaon a)*
Corresponding author:
[email protected] b)* another author :
[email protected]
Abstract. This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni 2+ ions in the system.
INTRODUCTION In year 2000, Dietl et al. [1] predicted the possibility of ferromagnetism in oxide based semiconductors with high Curie temperature. After that, a huge community of researchers has started to work in this direction and reported the ferromagnetism at room temperature in rare-earth or transition metal doped oxide based semiconductors which were based on carrier mediated mechanism. This theoretical prediction and experimental investigations of room temperature ferromagnetism leads to a challengeable search of such kind of materials. Firstly, spintronics [2] was studied in magnetoresistive sensors and memory storage devices which were fabricated from the alloys of 3d transition metal such as Co, Ni, Fe doped in non-magnetic substance lattice like ZnO, CeO2, SnO2, TiO2, GaAs etc. termed as dilute magnetic semiconductors (DMS). However, few recent studies on DMS developed interest because of some controversial issues like why strong ferromagnetism observed in samples doped with non-magnetic elements such as Vanadium; why does curie temperature is independent of concentration of magnetic element; while in some cases, it also has been seen that bulk shows non-magnetic behavior but the thin films prepared of same composition exhibits magnetism, etc [3-6]. Among various oxide based DMS, tin oxide (SnO 2) is one of the promising candidate because of its potential applications in the field of gas sensors, solar cells, lithium ion batteries, gas discharge display, transparent conducting electrodes due to its remarkable properties such as high electrical conductivity, optical transparency, chemical and thermal stabilities. It is a well known n-type semiconductor with a wide band gap of ~3.6 eV and has rutile tetragonal structure similar to TiO2. Doping of transition metal (TM) in this semiconductor modifies its structural, optical and magnetic behavior from bulk to its thin film form. In addition, it may be considered as a host semiconductor for the fabrication of dilute magnetic semiconductor (DMS) because of its high carrier density and local oxygen vacancies.
2nd International Conference on Condensed Matter and Applied Physics (ICC 2017) AIP Conf. Proc. 1953, 120010-1–120010-3; https://doi.org/10.1063/1.5033075 Published by AIP Publishing. 978-0-7354-1648-2/$30.00
120010-1
EXPERIMENTAL DETAIL The Sn1-xNixO2 (x= 2% and 10%) thin films were deposited on silicon (Si) substrate using pulse laser deposition (PLD) technique under oxygen partial pressure (P O2) with a laser frequency of 10 Hz and deposition time of 30 min was kept fixed for both the samples. Basically, the films were deposited under P O2 with a base pressure of 1.0x10-6 Torr and substrate temperature was 400 OC; the pressure was maintained as 1.0x10-6 Torr during deposition. The deposited films were characterized using NEXAFS and DC magnetometer for the investigation of influence of doping concentration on their electronic structure and magnetic behavior.
RESULT AND DISCUSSION Electronic Structure Figure1 represents the NEXAFS spectra of Ni L3, 2 edge of Sn1-xNixO2 thin films. The spectral features of Ni L3 edge represents transition from Ni 2p3/2 core level to 3d state and L2 edge corresponds to transition from Ni 2p1/2 to 3d level. The separation energy between Ni 2p3/2 and Ni 2p1/2 is ~ 18 eV. This splitting of L edge is due to spin orbit interaction. Ni 2p3/2 is further split into two features as a result of crystal field splitting. The intensity of the peaks increases with the doping content might be due to change in Ni coordination geometry. All these spectral studies implies that the doping of Ni ion within the SnO2 lattice highly influence the electronic structure of the material.
Figure 1. NEXAFS spectra of Ni L3, 2 edge of Sn1-xNixO2 thin films
Magnetic Behavior Figure 2 shows the magnetization versus magnetic field curves of Ni: SnO 2 thin films samples with Ni doping concentration of 2% and 10%. From the magnetization measurements, a clear hysteresis loop has been observed, revealing that thin films are definitely ferromagnetic in nature which may be due to the presence of vacancies created at the oxygen site in the SnO2 system or might be due to the defects created by the substitution of Ni ions in the SnO 2 lattice. Moreover, it can be seen from the figure 2 that the saturation magnetization (Ms) increases with the increase in doping concentration which is nearly 4.51×10-4 emu/cm3 for 10% Ni doping in SnO2 thin film.
120010-2
Figure 2. M-H curve of Ni doped SnO2 thin film
CONCLUSION The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice of SnO2 thin film deposited by PLD technique. In addition, M-H curve has also been studied for Ni doped SnO2 thin film. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni 2+ ions in the system.
ACKNOWLEDGMENTS Mayuri Sharma and P. A. Alvi are grateful to ‘‘Banasthali Center for Research and Education in Basic Sciences’’ under CURIE programme supported by the DST, Government of India, New-Delhi. Shalendra Kumar is also thankful to Department of Science and Technology, New Delhi (YSS/2015/001262) for financial support.
REFERENCES 1. 2. 3. 4. 5. 6.
T. Dietl, H. Ohno, F. Matsukura, J. Cibert, & E. D. Ferrand, “Zener model description of ferromagnetism in zincblende magnetic semiconductors”, science 287,No. 5455(2000), 1019-1022. M. Ziese and M.J. Thornton (Eds.), “Spin Electronics”, Lecture Notes in Physics Vol. 569(2001), Springer, Berlin. N.H. Hong, J. Sakai, N.T. Huong, N. Poirot, & A. Ruyter, "Role of defects in tuning ferromagnetism in diluted magnetic oxide thin films", Physical Review B 72.4 (2005): 045336. N.H. Hong, J. Sakai, and A. Hassini, "Ferromagnetism at room temperature with a large magnetic moment in anatase V-doped TiO2 thin films", Applied physics letters 84.14 (2004): 2602-2604. M. Venkatesan, C. B. Fitzgerald, J. G. Lunney, and J. M. D. Coey, "Anisotropic ferromagnetism in substituted zinc oxide", Physical Review Letters 93, no. 17 (2004): 177206. N.H. Hong, B. Virginie, and J. Sakai, "Mn-doped ZnO and (Mn, Cu)-doped ZnO thin films: Does the Cu doping indeed play a key role in tuning the ferromagnetism?", Applied Physics Letters 86.8 (2005): 082505.
120010-3
