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1. Influence of graphene on the magnetic properties of nickel ferrite nanoparticles

   https://doi.org/10.1016/j.ssi.2020.115425  

   Sorescu, Monica; Knauss, Matthew; Perrin, Alice; McHenry, Michael (November 2020, Solid State Ionics)

   null (Ed.)
2. Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

   https://doi.org/10.1021/acs.jpcc.2c00529  

   Anantharamaiah, Pendaranahalli Nadikeraiah; Rao, Prerna; Shashanka, Hadonahalli Munegowda; Khopkar, Vijay; Arout Chelvane, Jeyaramane; Sahoo, Balaram; Ramana, C. V. (June 2022, The Journal of Physical Chemistry C)
3. Strain induced anisotropy in liquid phase epitaxy grown nickel ferrite on magnesium gallate substrates

   https://doi.org/10.1038/s41598-022-10814-8  

   Liu, Ying; Zhou, Peng; Regmi, Sudhir; Bidthanapally, Rao; Popov, Maksym; Zhang, Jitao; Zhang, Wei; Page, Michael R.; Zhang, Tianjin; Gupta, Arunava; et al (December 2022, Scientific Reports)

   Abstract This work focuses on the nature of magnetic anisotropy in 2.5–16 micron thick films of nickel ferrite (NFO) grown by liquid phase epitaxy (LPE). The technique, ideal for rapid growth of epitaxial oxide films, was utilized for films on (100) and (110) substrates of magnesium gallate (MGO). The motivation was to investigate the dependence of the growth induced anisotropy field on film thickness since submicron films of NFO were reported to show a very high anisotropy. The films grown at 850–875 C and subsequently annealed at 1000 C were found to be epitaxial, with the out-of-plane lattice constant showing unanticipated decrease with increasing film thickness and the estimated in-plane lattice constant increasing with the film thickness. The uniaxial anisotropy field H σ , estimated from X-ray diffraction data, ranged from 2.8–7.7 kOe with the films on (100) MGO having a higher H σ value than for the films on (110) MGO. Ferromagnetic resonance (FMR) measurements for in-plane and out-of-plane static magnetic field were utilized to determine both the magnetocrystalline the anisotropy field H 4 and the uniaxial anisotropy field H a . Values of H 4 range from −0.24 to −0.86 kOe. The uniaxial anisotropy field H a was an order of magnitude smaller than H σ and it decreased with increasing film thickness for NFO films on (100) MGO, but H a increased with film thickness for films on (110) MGO substrates. These observations indicate that the origin of the induced anisotropy could be attributed to several factors including (i) strain due to mismatch in the film-substrate lattice constants, (ii) possible variations in the bond lengths and bond angles in NFO during the growth process, and (iii) the strain arising from mismatch in the thermal expansion coefficients of the film and the substrate due to the high growth and annealing temperatures involved in the LPE technique. The LPE films of NFO on MGO substrates studied in this work are of interest for use in high frequency devices. 

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4. Electric field tuning of a nickel zinc ferrite resonator by non-linear magnetoelectric effects

   https://doi.org/10.1038/s41598-023-45530-4  

   Popov, Maksym; Machi, Alexander; Inman, Jerad; Bidthanapally, Rao; Saha, Sujoy; Qu, Hongwei; Jain, Menka; Page, Michael R.; Srinivasan, Gopalan (October 2023, Scientific Reports)

   Abstract The nature of nonlinear magnetoelectric (NLME) effect has been investigated at room-temperature in a single-crystal Zn substituted nickel ferrite. Tuning of the frequency of magnetostatic surface wave (MSSW) modes under an applied pulsed DC electric field/current has been utilized to probe the effect. The frequencies of the modes at 8–20 GHz were found to decrease by ~ 400 MHz for an applied DC powerPof ~ 100 mW and the frequency shift was the same for all of the MSSW modes and linearly proportional toP. A model is proposed for the effect and the NLME phenomenon was interpreted in terms of a reduction in the saturation magnetization due to the DC current. The decrease of magnetization with applied electric power, estimated from data on mode frequency versusP, was − 2.50 G/mW. The frequency tuning efficiency of the MSSW modes due to NLME effects in the ferrite resonator was found to be 4.1 MHz/mW which is an order of magnitude higher than the shift reported for M-type strontium and barium hexaferrite resonators investigated earlier. The spinel ferrite resonator discussed here has the potential for miniature, electric field tunable, planar microwave devices for the 8–20 GHz frequency range. 

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5. Optical studies of pure and (Cu, Co) doped nickel zinc ferrite films deposited on quartz substrate

   https://doi.org/10.1116/6.0002262  

   Kothapally, Sneha; Kotru, Sushma; Paul, Roni; Abu Qahouq, Jaber A. (March 2023, Journal of Vacuum Science & Technology A)