A composite free layer (CFL) consisting of a soft layer and a hard layer exchange coupled in parallel is proposed. The experimental results showed that the critical current density (Jc) can be reduced from 7.05×106A∕cm2 of strong coupled CoFeB(12.5Å)∕Ru(4Å)∕NiFe(17.5Å) CFL to 2.65×106A∕cm2 of weak coupled CoFeB(12.5Å)∕Ru(15Å)∕NiFe(17.5Å) CFL. The macrospin simulations showed that the soft layer of CFL can assist the hard layer of CFL to switch at a lower Jc. These results suggest that by using CFL, it is possible to reduce the Jc of spin torque transfer switching without compromising the thermal stability.

Cobalt titanate (CoTiO3) powder was prepared by a modified sol‐gel method. The precursor solution could be prepared by cobalt acetate and titanium isopropoxide using various solvents either with or without HCl. After post‐heat treatment in air from 500 to 900 °C, CoTiO3 powder with increasing crystallinity was obtained. The fundamental properties of the powder were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Brunauer‐Emmett‐Teller (BET) analysis. The effects of post‐heat treatment at different temperatures were discussed based on results of these analyses. The results showed that single‐phase CoTiO3 can be prepared by straightforward sol‐gel spin‐coating method followed by heat treatment at fairly low temperature of 550 °C. The dielectric constant of the CoTiO3 powder thus prepared was found to be 34.5 by C‐V analysis. High‐k material application is promising for the CoTiO3 powder thus prepared.

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In this study, we utilize the current–voltage (I–V) measurement method for investigating the ferroelectric characteristics of ferroelectric capacitors, such as hysteresis loops, switching current characteristics, retention properties and depolarization characteristics. By applying triangular voltage wave forms without sweeping and measuring delay, the hysteresis switching current characteristic was determined and the polarization–voltage (P–V) loop could be obtained using an integral calculus. Additionally, two kinds of poling measurement were utilized to investigate the full-switching and nonswitching current characteristics. A strong agreement was found between nonvolatile polarization (ΔP) obtained from P–V loops and that obtained by poling measurements. Moreover, modified poling measurements were utilized to study the retention property of ferroelectric capacitors. A dynamic switching current characteristic was found in retention duration and an increased coercive voltage was also observed in its half-hysteresis loops as remaining time increased. Furthermore, another modified poling profile was utilized to investigate the depolarization characteristics of ferroelectric films.

We have developed a manufacturing-friendly spin-orbit torque magnetic random access memory (SOT-MRAM) technology in CMOS compatible 8-inch fab process. The proposed SOT-MRAM process technology resolves etching non-uniformity and reduction of high resistivity heavy-metal nanowire resistance issues. Besides, we present device size-dependent switching current threshold in the proposed SOT-MRAM cell structure. To realize the potential of our fabricated SOT-MRAM, wafer-level uniformity, cycling and temperature dependence SOT switching have been comprehensively investigated. Furthermore, the thermal stability factor () was calculated from temperature-dependence SOT switching to fulfill the thermal stability criteria, i.e., >10 years of this emerging SOT-MRAM technology. INDEX TERMS Spintronics, spin-orbit torque, spin-transfer torque, spin-hall effect, magnetic tunnel junction.

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