For decades, scientists have explored a group of unusual materials called multiferroics, known for their potential applications in computer memory, chemical sensors, and quantum computers. A recent study published in Nature by researchers from The University of Texas at Austin and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) has identified the layered multiferroic material nickel iodide (NiI2) as a leading candidate for extremely fast and compact devices.

Figure 1. Fast Transfer.

Figure 1 is for illustration purpose only. Multiferroics possess a unique property called magnetoelectric coupling, allowing the manipulation of magnetic properties with an electric field and vice versa. The research team discovered that NiI2 exhibits greater magnetoelectric coupling than any known material of its kind, making it an ideal candidate for technological advancements.

“Unveiling these effects at the scale of atomically thin nickel iodide flakes was a formidable challenge,” said Frank Gao, a postdoctoral fellow in physics at UT and co-lead author of the paper, “but our success presents a significant advancement in the field of multiferroics.” [1]

“Our discovery paves the way for extremely fast and energy-efficient magnetoelectric devices, including magnetic memories,” added graduate student Xinyue Peng, the project’s other co-lead author.

Electric and magnetic fields are fundamental to our understanding of the world and modern technologies. Within a material, electric charges and atomic magnetic moments can order themselves, forming an electric polarization or magnetization, known as ferroelectrics or ferromagnets, respectively.

However, in the exotic materials that are multiferroics, electric and magnetic orders co-exist. The magnetic and electric orders can be entangled, such that a change in one causes a change in the other. This property, known as magnetoelectric coupling, makes these materials attractive for faster, smaller, and more efficient devices. For such devices to function effectively, materials with particularly strong magnetoelectric coupling are essential, as demonstrated with NiI2 in the study.

The researchers achieved this by exciting the material with ultrashort laser pulses in the femtosecond range (a millionth of a billionth of a second) and tracking the resulting changes in the material’s electric and magnetic orders and magnetoelectric coupling via their impact on specific optical properties [2].

To understand why NiI2 has stronger magnetoelectric coupling than similar materials, the team conducted extensive calculations.

“Two factors play important roles here,” said co-author Emil Viñas Boström of the MPSD. “One of them is the strong coupling between the electrons’ spin and orbital motion on the iodine atoms — that’s a relativistic effect known as spin-orbit coupling. The second factor is the particular form of the magnetic order in nickel iodide, known as a spin spiral or spin helix. This ordering is crucial both to initiate the ferroelectric order and for the strength of the magnetoelectric coupling.”

Materials like NiI2 with large magnetoelectric coupling have numerous potential applications, including compact, energy-efficient magnetic computer memory; interconnects in quantum computing platforms; and chemical sensors for quality control and drug safety in the chemical and pharmaceutical industries.

The researchers hope that these groundbreaking insights will aid in identifying other materials with similar magnetoelectric properties and that material engineering techniques could further enhance the magnetoelectric coupling in NiI2.

This work was conceived and supervised by Edoardo Baldini, assistant professor of physics at UT, and Angel Rubio, director of the MPSD.

The paper’s other UT authors are Dong Seob Kim and Xiaoqin Li. Other authors from MPSD are Xinle Cheng and Peizhe Tang. Additional authors are Ravish K. Jain, Deepak Vishnu, Kalaivanan Raju, Raman Sankar, and Shang-Fan Lee of Academia Sinica; Michael A. Sentef of the University of Bremen; and Takashi Kurumaji of the California Institute of Technology.

Funding for this research was provided by the Robert A. Welch Foundation, the U.S. National Science Foundation, the U.S. Air Force Office of Scientific Research, the European Union’s Horizon Europe research and innovation program, the Cluster of Excellence “CUI: Advanced Imaging of Matter,” Grupos Consolidados, the Max Planck-New York City Center for Non-Equilibrium Quantum Phenomena, the Simons Foundation, and the Ministry of Science and Technology in Taiwan.

Source: University of Texas at Austin

References:

1. https://cns.utexas.edu/news/research/paving-way-extremely-fast-compact-computer-memory
2. https://interestingengineering.com/science/strongest-magnetoelectric-material-faster-compact-memory

Cite this article:

Hana M (2024), Breakthrough in Multiferroics: Nickel Iodide Emerges as Top Candidate for Fast, Compact Devices, AnaTechmaz, pp. 311