Study of Ferromagnetic Properties and Finite Tunnel Density in Mn Doped ZnTe Quantum Dots for Magnetic Tunnel Junction Applications

Abstract Ferromagnetic properties of Manganese doped Zinc Telluride (ZnTe) Quantum Dots (QDs) has been studied and analysed in this articles. Paramagnetic behavior of undoped ZnTe QDs and signatures of feeble ferromagnetism in 10% and 20% Mn 2+ doped Zinc Telluride (ZnTe) quantum dots (QDs) and disappearance of ferromagnetism in 30% Mn 2+ doped ZnTe QDs are identified using Vibrating Sample Magnetometer (VSM), in the sol‐gel grown, hexagonal structured QDs. Mn 2+ ‐ V O – Mn 2+ interactions between two Mn 2+ ions via F‐center like defects is understood to have led to ferromagnetic coupling in these QDs. F‐center like defects might have migrated and vanished, making ferromagnetism to disappear in 30% Mn 2+ doped ZnTe QDs; however paramagnetism is found to persist due to isolated spins. The dominant dipole‐dipole interactions between the Mn 2+ ions make the hyperfine structure poorly resolved and broad EPR spectra are seen in 20% Mn 2+ and 30% Mn 2+ doped ZnTe QDs. An I‐V measurement of a planar structure of QDs shows that unlike bulk tunnel barriers, a single met al. junction with a ZnTe QDs, exhibiting a magnetic tunneling effect as a small current is observed. This here illustrates the state of finite tunnel density in the as synthesized QDs. Such novel QDs can be applied for the future applications of magnetic tunnel junction devices.