Theoretical analysis of the novel samarium nickelate (SmNiO₃)-based broadband terahertz (THz) metamaterial absorbers

Abstract

Samarium nickelate, SmNiO₃ (SNO), a novel phase-changing material, is used for the first time in designing and developing a broadband metamaterial absorber for potential THz applications. Two unique designs are proposed in this article, comprising a three-layered composition incorporating SNO as the top resonator layer and gold (Au) as the ground layer, which are separated by an underexplored yet promising dielectric material known as lithium metagermanate, Li₂GeO₃ (LGO). The simulation results showed that both the auxetic and concentric circular ring patterns provide significant absorption performance at normally incident THz waves. For instance, the proposed auxetic patterned structure is maintained over 90% absorption from 4.24 to 11.41 THz, exhibiting a bandwidth of 7.17 THz and a relative absorption bandwidth (RAB) of 91.62%. On the other hand, the proposed circular patterned structure is maintained above 90% absorption, ranging from 2.77 THz to 11.13 THz, showing a bandwidth of 8.36 THz and an RAB of 120.29%. The numerical analysis validates wide-angle absorption for different incident angles in transverse electric (TE) and transverse magnetic (TM) modes and polarization insensitivity. Being equipped with prominent characteristics like broadband and consistent absorption, angular stability and tunability, the introduced SNO-based meta-absorbers open a new door of possibilities and display excellent application prospects in emerging THz applications.