Tunable order in colloids of hard magnetic hexaferrite nanoplatelets

High-coercivity hexaferrite ceramics featuring sub-terahertz ferromagnetic resonance

“…[25][26][27][28][29][30] Also, the ferrites are promising for spintronics 31,32 and various developing applications that require stable nanomagnets, e.g. magnetic recording, 33,34 ferrogels, 35,36 ferrofluids, [37][38][39] nanocomposites, [40][41][42][43][44] self-assembling systems, [45][46][47][48][49][50][51] etc.…”

Sprayed Nanometer-Thick Hard-Magnetic Coatings with Strong Perpendicular Anisotropy for Data Storage Applications

“…The coercive force effectively increases from 3.95 kOe for weakly interacting individual platelets at distances larger than 100 nm to >4.5 kOe for the nanoplatelet stacks with decreasing interparticle distance (see the Supporting Information, Figure S1). 41 The absence of well-defined anisotropy of the hysteresis loop in parallel and perpendicular field orientations of the nanoplatelet stacks is consistent with the single-domain structure of such concentrated magnetic liquids.…”

“…38 Contrary to the traditional magnetic liquids, such colloids contain fine single-domain ferromagnetic nanoplatelets with a rigidly fixed magnetic moment that's stabilized with a strong magnetocrystalline anisotropy of SrFe 12 O 19 . 39 In contrast to the properties of the fixed individual particle, the magnetic properties of a ferromagnetic colloid exhibit a minimal magnitude of the coercive force of the order of several Oersted due to the ability of magnetic particles to freely change their orientation in a liquid medium by the action of a minimal external magnetic field 38,40,41 and allow for facile manipulation during the drying process.…”

“…The prepared colloidal solutions were centrifuged for 120 min and then held on the magnet until concentrated phase formation for more accessible storage and further processing. 41 The concentrated phase was diluted to restore the initial colloid state before spray deposition. Thermogravimetric analysis (TGA) was performed to determine the actual sample concentration.…”

Tuning the morphology and magnetic properties of single-domain SrFe8Al4O19 particles prepared by a citrate auto-combustion method

“…Although M-type hexaferrites (BaFe12O19 and SrFe12O19) are well-studied compounds, they are still of great interest due to unique set of finely tunable functional properties 1 . Large magnetocrystalline anisotropy and high coercivity form the basis for their wide applications as permanent magnets 2 , and high thermal and chemical stability make it possible to produce nanomagnets for magnetic recording media [3][4][5] , fast-response magneto-active colloids 6,7 and hard magnetic cores of exchange-coupled nanocomposites 8,9 . Moreover, the hexaferrites display specific millimeter-wave (sub-THz) absorption due to ferromagnetic resonance (FMR), which is essential for modern wireless communication technologies [10][11][12][13] .…”