The Magnetic Properties on the MgO/CoFeB/Ta/Co/Pt structures

At the interface between a heavy metal (HM) and a ferromagnet (FM), interfacial phenomena such as an interfacial perpendicular magnetic anisotropy (iPMA), interfacial Dzyaloshinskii-Moriya interaction (iDMI) appear because of their strong spin-orbit coupling (SOC) [1]. The element with large SOC strength as an interface at the HM/FM may provide a large modulation of the iPMA and iDMI values. Furthermore, there are numerous studies that the orbital hybridization at the interface between FM and the oxide layer can improve the iPMA for developing magnetoresistive random access memory with high thermal stability [2]. In this study, we investigate the Co layer thickness dependent magnetic properties on the MgO (5 nm)/ Co40Fe40B20 (0.6 nm)/Ta (0.2 nm)/Co (0.8, 1.0, 1.2, 1.4, 1.6, 1.8 nm)/Ta (5 nm) structure fabricated by magnetron sputtering system. Furthermore, to investigate the annealing effect of MgO/CoFeB/Ta layer, the series of samples were annealed at 300 o C, 1hour. The systematic Brillouin light scattering measurements are performed for the fabricated sample to investigate magnetic properties. As shown in Table 1, the determined values of saturation magnetization (Ms), iPMA energy (Ks), and normalized iDMI energy density (Ds) of 300 o C annealed samples are increased by 30 % (compare with as-deposited samples). These results can open a new path to spintronic devices

Fabrication of Domain Wall Inverter for Dynamic Logic Devices

Recently, the spin torque majority gate (STMG) is paid great attention to developing next-generation logic devices with ultralow power consumptions since STMG can reduce the circuit architectures such as several transistors, circuit length, etc. Especially, the magnetic inverter is essential for the STMG logic devices to demonstrate NOT gate. There are several methods to realize NOT gate in the spintronics based on logic devices [1,2]. In this study, the interlayer exchange coupling (IEC) is used to demonstrate the STMG inverter based on the current-driven magnetic domain wall (DW) motion. In this research, we demonstrate the STMG inverter in the Ta/Pt/Co/Pt/Ru/Pt/Co Pt structure fabricated by the lift-off method including Chemical-Mechanical Planarization (CMP). The CMP Process is one of the wide-area planarization process operations, and here, matching the height of the passivated oxide layer and the bottom ferromagnetic layer. The top ferromagnetic layer is deposited on the bottom FM layer overlapped 3 mm region. Fig. 1 (a) shows the detailed procedure. Figure 1 (b) shows the structure of the STMG inverter. The stack consisted of an antiferromagnetic coupling of IEC using the perpendicularly magnetized Pt/Co/Pt/Ru/Pt/C /Pt structures. We will discuss processing the inverter. This result can open a new path to explore the next-generation logic devices based on the current-induced magnetic domain wall motion