Characterization of Voltage Controlled Magnetic Anisotropy for Magnetic Logic Devices

Student Name: Jack Guarnery Home Institution: University of Texas at Austin NNCI Site: University of Texas at Austin REU Principal Investigator: Dr. Jean Anne Incorvia – Department of Electrical and Computer Engineering, UT Austin REU Mentor: Nickolas Zogbi – Department of Electrical and Computer Engineering, UT Austin Abstract: Voltage Controlled Magnetic Anisotropy (VCMA) is an interfacial effect that occurs between an iron-based ferromagnet and an oxide that allows for modification of the magnetization at the interface. VCMA is important for reducing the energy required to de-pin domain walls and increasing the reliability of switching in domain wall Magnetic Tunnel Junction (MTJ) logic devices. Traditionally, the domain wall in MTJ logic devices is pinned using a physical notch that requires a large current pulse to de-pin and subsequently switch. VCMA reduces the energy required to switch devices by eliminating the physical notch in exchange for a pinning method that can be controlled electrically. Different oxides have different VCMA coefficients corresponding to the strength of the interfacial effect. Characterization of the VCMA coefficient is possible using the Anomalous Hall Effect. By fabricating Hall Bars, we can measure changes in the Hall resistance due to VCMA, allowing us to calculate the VCMA coefficient. During my REU I have fabricated CoFeB-based Hall Bars with SiO2 and Al2O3 oxide layers, helped design the Hall measurement setup, and taken measurements of out-of-plane and in-plane Hall loops.