Photo of Zhaochu LUO

Nanotechnology & materials

Zhaochu LUO

Offering a new route to solve the von Neumann bottleneck problem in conventional computers.

Year Honored

Nanomagnet devices have a wide range of applications in data storage, magnetic sensors and bioengineering. Due to the presence of magnetic dipole interactions between the neighboring nanomagnets, the nanomagnet array provides a physical platform to explore magnetic phase transitions and to perform logic operations. However, high strength of the magnetic dipole interaction requires a large volume of the magnet, which greatly hinders the application in nanomagnet devices.

In 2019, Luo demonstrated a novel chirally coupled nanomagnet system by exploiting interfacial Dzyaloshinskii–Moriya interaction (DMI) in magnetic multilayers. The strength of chiral coupling can be 2 orders of magnitude higher than that of magnetic dipole coupling with the same volume of magnets.

Based on this chiral coupling, Luo has achieved lateral exchange bias, field-free switching of nanomagnets, artificial spin ice, and magnetic skyrmions.

In 2020, Luo demonstrated a method for performing all-electric logic operations and cascading using domain-wall racetracks. The domain-wall inverter, the essential basic building block in all implementations of Boolean logic, has been realized by exploiting the chiral coupling between neighboring magnetic domains.

Reconfigurable NAND and NOR logic gates have been fabricated and operated with current-induced domain-wall motion. Several gates (including 15 NAND logic gates and 3 NOT logic gates) have been cascaded to build a full adder, demonstrating electrical control of magnetic data and device interconnection in logic circuits. This work provides a viable platform for scalable all-electric magnetic logic, paving the way for memory-in-logic applications.

In addition, Luo proposed a current-driven magnetic diode. The discovery can make magnetic domain circuits work under alternating current, which expands the application regime of domain-wall devices. The applicant has also realized a spin torque-driven magnetic domain injection, enabling efficient domain-wall nucleation.

By exploiting the magnetoelectric response and nonlinear transport properties of silicon, Luo proposed three types of silicon-based logic-in-memory devices: silicon-based diode-enhanced magnetic logic device, CoFeB-based diode-enhanced magnetic logic devices, negative resistance-enhanced magnetic logic devices.