[1] S M Yakout. Spintronics: Future technology for new data storage and communication devices. J Supercond Nov Magn, 33, 2557(2020).

[2] Z Chen, Y S Zhao, J Q Ma et al. Detailed XPS analysis and anomalous variation of chemical state for Mn- and V-doped TiO₂ coated on magnetic particles. Ceram Int, 43, 16763(2017).

[3] Y Matsumoto, M Murakami, T Shono et al. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide. Science, 291, 854(2001).

[4] A S Bolokang, F R Cummings, B P Dhonge et al. Characteristics of the mechanical milling on the room temperature ferromagnetism and sensing properties of TiO₂ nanoparticles. Appl Surf Sci, 311, 362(2015).

[5] B Choudhury, R Verma, A Choudhury. Oxygen defect assisted paramagnetic to ferromagnetic conversion in Fe doped TiO₂ nanoparticles. RSC Adv, 4, 29314(2014).

[6] J J Tian, H P Gao, H M Deng et al. Structural, magnetic and optical properties of Ni-doped TiO₂ thin films deposited on silicon (100) substrates by sol–gel process. J Alloy Compd, 581, 318(2013).

[7] A S Semisalova, Y O Mikhailovsky, A Smekhova et al. Above room temperature ferromagnetism in Co- and V-doped TiO₂— revealing the different contributions of defects and impurities. J Supercond Nov Magn, 28, 805(2015).

[8] L T Tseng, X Luo, S Li et al. Magnetic properties of Sm-doped rutile TiO₂ nanorods. J Alloy Compd, 687, 294(2016).

[9] S Paul, B Choudhury, A Choudhury. Magnetic property study of Gd doped TiO₂ nanoparticles. J Alloy Compd, 601, 201(2014).

[10] N N Xu, G P Li, Q L Lin et al. Structural and magnetic study of undoped and Cu-doped rutile TiO₂ single crystals. J Supercond Nov Magn, 30, 2591(2017).

[11] Z R Zou, Z P Zhou, H Y Wang et al. Effect of Au clustering on ferromagnetism in Au doped TiO₂ films: theory and experiments investigation. J Phys Chem Solids, 100, 71(2017).

[12] J B Wang, K C Wu, J W Mi et al. Room-temperature ferromagnetism in carbon- and nitrogen-doped rutile TiO₂. Appl Phys A, 118, 725(2015).

[13] G D Wei, L Wei, Y X Chen et al. Magnetic coupling and electric transport in Nb, Fe co-doped rutile TiO₂ epitaxial films. J Alloy Compd, 695, 2261(2017).

[14] S A Ahmed. Annealing effects on structure and magnetic properties of Mn-doped TiO₂. J Magn Magn Mater, 402, 178(2016).

[15] S A Ahmed. Ferromagnetism in Cr-, Fe-, and Ni-doped TiO₂ samples. J Magn Magn Mater, 442, 152(2017).

[16] A Chanda, K Rout, M Vasundhara et al. Structural and magnetic study of undoped and cobalt doped TiO₂ nanoparticles. RSC Adv, 8, 10939(2018).

[17] C Stella, D Prabhakar, M Prabhu et al. Oxygen vacancies induced room temperature ferromagnetism and gas sensing properties of Co-doped TiO₂ nanoparticles. J Mater Sci-Mater Electron, 27, 1636(2016).

[18] Y B Lin, Y M Yang, B Zhuang et al. Ferromagnetism of Co-doped TiO₂ films prepared by plasma enhanced chemical vapour deposition (PECVD) method. J Phys D, 41, 195007(2008).

[19] D L Cortie, Y Khaydukov, T Keller et al. Enhanced magnetization of cobalt defect clusters embedded in TiO_2–δ films. ACS Appl Mater Inter, 9, 8783(2017).

[20] B Santara, B Pal, P K Giri et al. Signature of strong ferromagnetism and optical properties of Co doped TiO₂ nanoparticles. J Appl Phys, 110, 114322(2011).

[21] R K Griffin, M Varela, S Rashkeev et al. Defect-dediated ferromagnetism in insulating Co-doped anatase TiO₂ thin films. Phys Rev B, 78, 014409(2008).

[22] S R Shinde, S B Ogale, J S Higgins et al. Co-occurrence of superparamagnetism and anomalous Hall effect in highly reduced cobalt-doped rutile TiO_2–δ films. Phys Rev Lett, 92, 166601(2004).

[23] J D Bryan, S A Santangelo, S C Keveren et al. Activation of high-TC ferromagnetism in Co²⁺: TiO₂ and Cr³⁺: TiO₂ nanorods and nanocrystals by grain boundary defects. J Am Chem Soc, 127, 15568(2005).

[24] K Srinivas, P V Reddy. Synthesis, structural, and magnetic properties of nanocrystalline Ti_0.95Co_0.05O₂-diluted magnetic semiconductors. J Supercond Nov Magn, 27, 2521(2014).

[25] A Kaushik, B Dalela, S Kumar et al. Role of Co doping on structural, optical and magnetic properties of TiO₂. J Alloy Compd, 552, 274(2013).

[26] S Sharma, N Thakur, R K Kotnala et al. Structure and magnetic properties of Ti_{1 –x}Co_xO₂ nanoparticles prepared by chemical route. J Cryst Growth, 321, 19(2011).

[27] S Kumar, J S Park, D J Kim et al. Electronic structure and magnetic properties of Co doped TiO₂ thin films using X-ray absorption spectroscopy. Ceram Int, 41, S370(2015).

[28] S R Shinde, S B Ogale, S D Sarma et al. Ferromagnetism in laser deposited anatase Ti_1–xCo_xO_2–δ films. Phys Rev B, 67, 115211(2003).

[29] K Karthik, S K Pandian, K S Kumar et al. Influence of dopant level on structural, optical and magnetic properties of Co-doped anatase TiO₂ nanoparticles. Appl Surf Sci, 256, 4757(2010).

[30] L T Tseng, X Luo, T T Tan et al. Doping concentration dependence of microstructure and magnetic behaviours in Co-doped TiO₂ nanorods. Nanoscale Res Lett, 9, 673(2014).

[31] B Choudhury, A Choudhury, A K M MaidulIslam et al. Effect of oxygen vacancy and dopant concentration on the magnetic properties of high spin Co²⁺ doped TiO₂ nanoparticles. J Magn Magn Mater, 323, 440(2011).

[32] H Zhang, M X Chen, Y Z Wang et al. Correlation between oxygen vacancies and room temperature ferromagnetism in Ti_0.94Co_0.03La_0.03O₂ nanoparticles influenced by different post annealing treatment. J Sol–gel Sci Techn, 86, 162(2018).

[33] H Zhang, W Q Huang, R Lin et al. Room temperature ferromagnetism in pristine TiO₂ nanoparticles triggered by singly ionized surface oxygen vacancy induced via calcining in different air pressure. J Alloy Compd, 860, 157913(2021).

[34] H Zhang, L Q Zheng, X H Ouyang et al. Carbon doping of Ti_0.91Co_0.03La_0.06O₂ nanoparticles for enhancing room-temperature ferromagnetism using carboxymethyl cellulose as carbon source. Ceram Int, 44, 15754(2018).

[35] H Zhang, Y Xu, W B Yang et al. Structural and magnetic evolution of Fe-doped TiO₂ nanoparticles synthesized by sol–gel method. J Electroceram, 38, 104(2017).

[36] H Y Lee, S J Clark, J Robertson. Calculation of point defects in rutile TiO₂ by the screened-exchange hybrid functional. Phys Rev B, 86, 075209(2012).

[37] S Na-Phattalung, M F Smith, K Kim et al. First-principles study of native defects in anatase TiO₂. Phys Rev B, 73, 125205(2006).

[38] B Santara, P K Giri, S Dhara et al. Oxygen vacancy-mediated enhanced ferromagnetism in undoped and Fe-doped TiO₂ nanoribbons. J Phys D, 47, 235304(2014).

[39] S K S Patel, N S Gajbhiye, S K Date. Ferromagnetism of Mn-doped TiO₂ nanorods synthesized by hydrothermal method. J Alloy Compd, 509, S427(2011).

[40] M S Mahmoud, E Ahmed, A A Farghalid et al. Synthesis of Fe/Co-doped titanate nanotube as redox catalyst for photon-induced water splitting. Mater Chem Phys, 217, 125(2018).

[41] H M Yadav, J S Kim. Sol–gel synthesis of Co²⁺-doped TiO₂ nanoparticles and their photocatalytic activity study. Sci Adv Mater, 9, 1114(2017).

[42] A Kumar, M K Kashyap, N Sabharwal et al. Structural, optical and weak magnetic properties of Co and Mn codoped TiO₂ nanoparticles. Solid State Sci, 73, 19(2017).

[43] Z H Li, W W Zhong, X M Li et al. Strong room-temperature ferromagnetism of pure ZnO nanostructure arrays via colloidal template. J Mater Chem C, 1, 6807(2013).