Researchers are advancing energy-efficient supercomputing by harnessing charge density waves in materials, a technique that mimics brain neurons. New microscopy methods at Argonne National Laboratory show how these waves can be manipulated by electricity, offering insights into faster, smaller and more efficient microelectronic devices. Source: SciTechDaily.com
Charge density waves find application in the next generation of energy-efficient computers.
Scientists have used an ultrafast electron microscope to capture the nanosecond changes in a material during electrical pulses. Understanding these changes could lead to more energy-efficient electronics.
Today’s supercomputers consume enormous amounts of energy, equivalent to the electricity consumption of thousands of homes. In response, researchers are developing a more energy-efficient, next-generation form of supercomputing that uses artificial neural networks. These networks mimic the processes of neurons, the basic unit of the human brain. This mimicry could be achieved through the charge density waves that occur in certain materials. Charge density waves are wave-like patterns of electrons – negatively charged particles – moving in a correlated manner.
Deciphering the dynamics of charge density waves
The charge density waves increase the resistance to the movement of electrons in the material. The ability to control the waves could allow the resistance to be switched on and off quickly. This property could then be used for more energy-efficient computing as well as ultra-precise sensing. However, it is not clear how the switching process occurs, especially given that the waves change from one state to another within 20 billionths of a second.
“This new technique has produced results that have broad applications in energy-efficient microelectronics.”
— Charudatta Phatak, materials scientist and deputy head of department
Advances in microscopy at Argonne National Laboratory
Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have found a new way to study these waves. They used the ultrafast electron microscope at the Center for Nanoscale Materials, a DOE Office of Science facility at Argonne. They developed a new microscopy technique that uses electrical pulses to observe nanosecond dynamics in a material known to form charge density waves at room temperature. This material is a tantalum sulfide called 1T-TaS.2.
The team tested a flake of this sulfide with two electrodes attached to it to generate electrical pulses. With short pulses, it was thought that the resulting high electric field or currents could cause the resistive switching. But two observations using the ultrafast electron microscope changed this understanding.
Diffraction pattern taken before and after a 20 nanosecond electrical pulse. The star-shaped pattern of small white dots (left) corresponds to the initial charge density wave pattern, which is temporarily melted by the heat of the electrical pulse (right). Image credit: Argonne National Laboratory
First, the charge density waves melted in response to the heat generated by the injected current rather than the charging current itself, even during nanosecond pulses. Second, the electrical pulses induced drum-like vibrations throughout the material, shaking the wave array.
“This new technique has allowed us to discover two previously unobserved ways in which electricity can manipulate the state of charge density waves,” said Daniel Durham, a postdoctoral researcher at Argonne. “And the melting response mimics how neurons are activated in the brain, while the vibration response could generate neuron-like firing signals in a neural network.”
This study shows a new approach to studying this type of electrical switching process. Using this ultrafast electron microscopy method, researchers can observe how microelectronic materials Nanometer lengths and nanosecond speeds.
The trend towards smaller, faster and more efficient microelectronic devices makes a material like 1T-TaS2 attractive. And because it can be formed as a nanoscale layer, it is also attractive for such devices.
This new technique has produced results with a wide range of applications in energy-efficient microelectronics, says Charudatta Phatak, materials scientist and deputy department head at Argonne.
“Understanding the fundamental mechanisms of how we can control these charge density waves is important because this can be applied to other materials to control their properties,” Phatak said.
This research was published in Physical Examination Letters.
Reference: “Nanosecond structural dynamics in the electrical melting of charge density waves in 1T−TaS2” by Daniel B. Durham, Thomas E. Gage, Connor P. Horn, Xuedan Ma, Haihua Liu, Ilke Arslan, Supratik Guha and Charudatta Phatak, May 28, 2024, Physical Examination Letters.
DOI: 10.1103/PhysRevLett.132.226201
In addition to Durham and Phatak, authors include Thomas Gage, Connor Horn, Xuedan Ma, Haihua Liu, Ilke Arslan and Supratik Guha. Horn and Guha have joint appointments at University of Chicago.
This work was supported by a DOE Office of Science Microelectronics Research Grant.
