October 2024

Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center (EFRC), University of Wisconsin-Madison, University of Colorado Boulder, Duke University and University of Utah have discovered a new process to induce chirality in halide perovskite semiconductors, which could open the door to cutting-edge electronic applications.

The development is the latest in a series of advancements made by the team involving the introduction and control of chirality. Chirality refers to a structure that cannot be superimposed on its mirror image, such as a hand, and allows greater control of electrons by directing their spin. The researchers have been able to create a spin-polarized LED using chiral perovskite semiconductor in the absence of extremely low temperatures and a magnetic field, as was previously reported. The newest advance accelerates the materials development process for spin control.

Magnetic skyrmions have so far been treated as two-dimensional spin structures characterized by a topological winding number. However, in real systems with the finite thickness of the device material being larger than the magnetic exchange length, the skyrmion spin texture extends into the third dimension and cannot be assumed as homogeneous.

A 3D reconstruction of a skyrmion derived from X-ray images. Credit: Berkeley Lab

Researchers at Lawrence Berkeley National Laboratory, Swiss Light Source (Paul Scherrer Institute) and Western Digital Research Center have used soft x-ray laminography to reconstruct, with about 20-nanometer spatial (voxel) size, the full three-dimensional spin texture of a skyrmion in an 800-nanometer-diameter and 95-nanometer-thin disk patterned into a 30× [iridium/cobalt/platinum] multilayered film.

In a recent sturdy, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Northern Illinois University discovered that they could use light to detect the spin state in a class of materials called perovskites (specifically in this research methylammonium lead iodide, or MAPbI₃). 

To understand spin, consider electrons orbiting the atomic nucleus. When atoms are close together, they can share some of their outer electrons, which creates a bond between them. Each bond contains two electrons that are ​“paired,” meaning they share an orbital — the region where they move. Now, each of these paired electrons has one of two possible spin states: spin up or spin down. If one electron is spin up, the other is spin down. Since we can’t know exactly which electron has which spin without looking at them, we say they exist in a quantum superposition — a state where they are both spin up and spin down until observed.

TDK Corporation has announced the development of a neuromorphic element called a “spin-memristor” that has very low power consumption. By mimicking the energy-efficient operation of the human brain, this element could cut the power consumption of AI applications down to 1/100th of traditional devices. Collaborating with the French research organization CEA (Alternative Energies and Atomic Energy Commission), TDK has shown that its “spin-memristor” can serve as the basic element of a neuromorphic device. 

Going forward, TDK will collaborate with the Center for Innovative Integrated Electronic Systems at Tohoku University on the practical development of the technology.