Researchers from the University of Maryland and other institutions have developed a new method for creating a special type of material structure known as a van der Waals heterostructure, which exhibits a property called multiferroicity at room temperature. Multiferroic materials possess both magnetic and electric properties, allowing their behavior to be controlled by electrical signals. This discovery, detailed in a recent paper published in the journal Science, marks a significant step toward the development of advanced electronic devices that can be manipulated with electricity. The team constructed a two-dimensional (2D) multiferroic heterostructure by combining two distinct materials: a ferromagnetic compound called triiron gallium ditelluride (Fe₃GaTe₂) and a ferroelectric material known as copper indium thiophosphate (CuInP₂S₆). These materials were first obtained in thin layers by mechanically separating them from larger crystals. The thin layers were then stacked vertically to form a heterostructure, held together by weak intermolecular forces known as van der Waals forces. To control the structure’s properties, the researchers added transparent electrodes made of indium tin oxide (ITO) and metallic chromium–gold (Cr/Au) electrodes to apply small voltages across the material. At room temperature (around 19°C), the heterostructure showed both the magnetic order of Fe₃GaTe₂ and the electric polarization of CuInP₂S₆. By applying a small voltage, the researchers were able to switch the material between different magnetic states. Remarkably, these states remained stable even after the voltage was removed. The team successfully switched between the two magnetic states over 3,000 times without signs of degradation. Additionally, the effect was most pronounced when the Fe₃GaTe₂ layers were thinnest, and the influence of the voltage decreased as the layers became thicker. This breakthrough could enable the creation of various room-temperature multiferroic materials with different compositions. Such materials could be useful in developing compact, non-volatile memory systems, as well as other electrically controlled devices in the fields of spintronics, magnetoelectrics, and magneto-optics. The ability to manipulate magnetic properties with electrical signals offers promising applications in next-generation electronics, potentially leading to more efficient and versatile technologies.