# Controllable Fano-like Resonance in Terahertz Planar Meta-Rotamers
## 1 Introduction  
The creation of metamaterials, which are artificially constructed composite materials with exceptional properties, has become an extremely interesting area of research in various fields, such as optics, optoelectronics, electromagnetic field, acoustics, and thermology [1, 2, 3, 4]. Artificial atoms (called meta-atoms) or molecules (called meta-molecules), as the basic structural elements for constructing metamaterials, are designed and fabricated to implement a device with the desired characteristics and functionalities. In particular, the meta-molecules created by engineering spatial arrangement or interatomic geometry of different types of meta-atoms achieve high-level functionalities, such as plasmon-induced transparency, multifunctional filtering, invisibility cloaking, tunable multiple resonators, reflective-index engineering, and Fano resonance [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18].  
Recently, metamaterials have promoted the inclusive development of terahertz (THz) materials and devices because of their resonant electromagnetic response, which significantly improves the interaction between THz radiation and metamaterials. In particular, developing THz devices and building a network connection in the THz frequencies have become key tasks for achieving sixth-generation (6G) wireless communication [19, 20]. This requires new techniques to manipulate the polarization, direction, amplification, collimation, resonance frequency, propagation, and phase of those THz waves. Thus, a THz metamaterial is the best candidate for realizing a device with such functionalities.  
Meta-molecules composed of different types of meta-atoms are fundamental elements that control the transmission, reflection, and absorption of light and realize the tunability of resonance wavelength at the THz frequencies. Various electromagnetically induced transparency (EIT)-analog optical systems based on THz metamaterials exhibit a narrow transmission or reflection spectral band and plasmon-induced transparency behavior [21, 22, 23, 24]. The EIT-like effects of bright-bright mode coupling, which occur when two resonances of two different types of meta-atoms are excited in close proximity in the spectral domain, inevitably lead to resonance frequency detuning based on Fano-type interference with ultrahigh quality factor (Q-factor) [25, 26, 27]. Therefore, metamaterialscomposed of meta-molecules are essential for fabricating versatile THz devices that require the ability to control resonance modes and spectral features.  
In this study, we numerically investigated a Fano-like-resonant planar THz metamaterial composed of meta-molecules consisting of two different types of meta-atoms, C- and Y-shaped metallic rods. In addition, we demonstrated that meta-rotamers based only on the difference in the spatial position of their component meta-atoms manifest tunable Fano-like resonance when optically isotropic, inner Y-shaped meta-atoms rotate. This phenomenon is caused by cooperative effects due to the spatial coupling conditions of the nodes and antinodes of the fundamental electric-dipole resonance of Y-shaped meta-atoms and higher-order inductive-capacitive (LC) resonance of C-shaped meta-atoms. Our study highlights the importance of metamaterials for achieving novel THz devices and their high-level functionalities.