Apr 27 2020
Researchers at KAUST have developed a new device that is solely controlled by voltage, opening the door for spintronics with ultralow power consumption.
For spintronic applications ranging from implantable medical devices and wearable electronics to data storage technologies, more energy-efficient devices can be developed by gaining the potential to manipulate the magnetization of electrodes created from ferromagnets.
The demand for information storage technologies with a higher capacity has led to the evolution of miniature devices known as magnetic tunnel junctions (MTJs). The MTJs are a potential means for the storage of huge amounts of data.
The MTJs are formed of tiny ferromagnets that are isolated by an ultrathin insulating layer. It is possible to switch their electrical resistance between low and high states, which correspond with the binary bits 0 and 1. They can be employed for information storage in magnetoresistive random access memory and other similar spintronic devices.
A magnetic field, spin-transfer torque, or a spin-orbit torque is conventionally used for this switching. In these techniques, a high electric current density is applied to the device, which eventually leads to the dissipation of large amounts of energy.
At present, Aitian Chen, KAUST collaborators, and researchers from the National University of Defense Technology in China have developed MTJs on ferroelectric substrates. It is possible to manipulate these MTJs by using only voltage, leading to a considerable reduction in energy consumption.
Integrating spintronics with multiferroics allows magnetic and electric properties of MTJs to be coupled and is a promising approach for the energy-efficient operation of MTJs.
Aitian Chen, Researcher, KAUST
The research team was able to manipulate the voltage of MTJs by first using the advanced sputtering and lithography facilities at KAUST to deposit high-quality MTJ films onto the ferroelectric substrates. Then, they used photolithography and ion milling to fabricate the devices.
Through the application of voltage to the ferroelectric substrate, the researchers were able to switch the magnetization configuration of the MTJs between parallel and antiparallel states. These states correspond with low and high electrical resistance, respectively.
The researchers used pairs of electrodes on the ferroelectric substrate to induce a piezostrain, modulating the ferromagnetic layer’s magnetization through a strain-induced magnetoelectric coupling.
Currently, we require two electrode pairs to achieve full control of MTJs, but the operation is very complicated. We are now looking to simplify the operation by using only one pair of electrodes.
Aitian Chen, Researcher, KAUST
Source: https://kaust.edu.sa/en