AUTHOR=Luo Qilin , Zhao Lingzhong , Zhou Jialin , Zhang Lin , Wen Guangfeng , Ba Qingtao , Wu Huabing , Lin Zhifang , Liu Shiyang 

TITLE=Magnetically Reconfigurable Unidirectional Propagation of Electromagnetic Waves by Zero-Index–Based Heterostructured Metamaterials

JOURNAL=Frontiers in Materials

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2022.845344

DOI=10.3389/fmats.2022.845344

ISSN=2296-8016

ABSTRACT=We present a zero-index based heterostructured magnetic metamaterials (HSMMs) composed of two arrays of ferrite rods with different radii, which exhibits unidirectional propagation of electromagnetic (EM) waves and the unidirectionality is reconfigurable dependent on the bias magnetic field (BMF). By calculating the photonic band diagrams and the effective constitutive parameters, it is shown that for the MMs with two groups of lattice separations and ferrite rod radii the effective refractive index is switched either from effective zero index (EZI) to effective positive index (EPI) by decreasing the BMF for one MM or from EZI to effective negative index (ENI) for the other MM by increasing the BMF. As a result, two kinds of the HSMMs can be constructed with the combination of either EZI and ENI or EZI and EPI, both of which can implement the unidirectional transport of EM waves and exhibit reconfigurable unidirectionality by either decreasing or increasing the BMF, thus providing us with more degree of freedom. The concept put forward in present work can be possibly extended to the heterostructured metamaterials made of phase-change materials and realize reconfigurable EM properties in optical frequency.