A Novel Approach to Design Luminomagnetic Pigment Formulated Security Ink for Manifold Protection to Bank Cheques against Counterfeiting

Abstract A new strategy for formulating a high‐security anti‐counterfeiting ink by synthesizing a pigment having both luminescent and magnetic features is demonstrated. The as‐synthesized pigment (Zn_0.98Mn_0.02S @ Gd_1.7Yb_0.2Er_0.1O₃ @ Fe₃O₄) emits intense orange (580 nm wavelength) and red (660 nm wavelength) color upon excitation with 351 and 980 nm wavelength, respectively. Moreover, the room temperature M–H curve of as‐synthesized pigment shows a typical ferromagnetic behavior. Due to the magnetic behavior of multi‐functional security ink along with dual‐mode luminescence, it can potentially be suitable to use for the printing of bank cheques (logos, magnetic ink character recognition codes), smart tags, etc., where the important information needs to be delicately encrypted and can be authenticated without being getting decoded. The security ink has been also studied using magnetic force microscopy for magnetic behavior and photoluminescence mapping to examine the uniform distribution of emission intensity over the printed pattern. Further, the patterns printed from the synthesized security ink are highly stable against the various bleaching agents and atmospheric conditions like hot, cold, and humid for the investigated period of six months. Hence, the new exceptional outcome of multi‐functional pigment formulated security ink offers a set of new distinctive features against counterfeiting.