Thermally Tunable Dual‐Functional Terahertz Metamaterials via Nonvolatile Phase Change Material

Precise control and on‐demand selection of distinct functionalities in metamaterials are essential for their advancement and application. A major challenge, however, is achieving simultaneous customization of multiple functions with different mechanisms within a single metamaterial. This study presents a thermally tunable dual‐functional terahertz (THz) metamaterial, leveraging a nonvolatile phase change material (Ge 2 Sb 2 Te 5 , GST). The metamaterial is composed of two aluminum sector rings, a polyimide middle layer, and a continuous GST film. At room temperature, it functions as a metal‐dielectric bilayer, interacting strongly with the incident THz beam to induce a bright–bright mode coupling and generate electromagnetically induced transparency (EIT). By applying high‐temperature stimulation, GST crystallizes, transforming the structure into a metal‐dielectric‐metal trilayer, which enables dual‐band near‐perfect absorption (NPA) due to magnetic resonance. This demonstrates the customization of two distinct functionalities, achieving an EIT intensity variation exceeding 41.8%, with absorbance variations of the two NPA peaks reaching 46.0% and 57.0%, respectively, significantly outperforming existing meta‐devices with single functions. This breakthrough could spark further research into high‐performance, compact, and integrated THz components.