Summary
UCLA researchers in the Department of Electrical Engineering have developed a voltage-controlled magnetic tunnel junction switch that can switch the magnetization of a magnetic bit (i.e. in a free layer) from one state to another using an applied voltage.
Background
The electronics industry continuously seeks for higher density devices that incorporate significant amounts of solid-state memory with minimal power consumption. Magnetic random-access memory (MRAM) devices by their nature provide non-volatile characteristics, as well as high speed, high endurance, high density and low power consumption compared to conventional RMA chip-based devices. However, magnetic memory devices, such as field-switched (toggle) MRAM, spin transfer torque MRAM, or thermally-assisted switching MRAM require substantial current flow for switching states through the layers of the magnetic tunnel junction (MTJ), an adjacent conductor, or by electric current-dependent heating of the MTJ. These devices thus offer only limited scalability to control and distribute large electric current for switching the devices. Accordingly, a need exists for high density and highly energy efficient magnetic memory devices.
Innovation
Researchers at UCLA have developed a voltage-controlled magnetic anisotropy (VCMA) switch (or magneto-electric junction (MEJ)) and magneto-electric RMA (MeRAM ir ME-MRAM) memory that can utilize in-plane or perpendicular magnetization. A voltage to change magnetization controls the switch state of the VCMA switch. The device relies on magnetic anisotropy, and electric field dependence of magnetic anisotropy for performing the switching. A non-volatile MeRAM relies on switching the state of a magnetic bit, comprising a VCMA switch, using an electric field (voltage) instead of magnetic fields or electrical currents. Thus, the VCMA switches and MeRAM devices perform switching without relying on the flow of electric change currents through the device or through a conductor placed close to the device, as they rely on the VCMA effect for switching.
Applications
▶ Non-volatile memory devices, particularly where low energy consumption is critical
- Mobile communication
- Computer systems
- Medical implants and sensors
Advantages
▶ A scalable alternative to other MRAM designs
▶ More energy efficient while retaining all other advantages of MRAM, such as non-volatility, high speed, high endurance and high density
State Of Development
The voltage-controlled out-of-plane anisotropy has been experimentally tested. Device prototype is currently under fabrication, and theoretical and simulation studies will be performed to facilitate improving the design.