The convergence of carbon nanomaterials and functional polymers has led to the emergence of smart carbon–polymer nanocomposites (CPNCs), which possess exceptional potential for next-generation sensing and actuation systems. These hybrid materials exhibit unique combinations of electrical, thermal, and mechanical properties, along with tunable responsiveness to external stimuli such as strain, pressure, temperature, light, and chemical environments. This review provides a comprehensive overview of recent advances in the design and synthesis of CPNCs, focusing on their application in multifunctional sensors and actuator technologies. Key carbon nanomaterials including graphene, carbon nanotubes (CNTs), and MXenes were examined in the context of their integration into polymer matrices to enhance performance parameters such as sensitivity, flexibility, response time, and durability. The review also highlights novel fabrication techniques, such as 3D printing, self-assembly, and in situ polymerization, that are driving innovation in device architectures. Applications in wearable electronics, soft robotics, biomedical diagnostics, and environmental monitoring are discussed to illustrate the transformative impact of CPNCs. Finally, this review addresses current challenges and outlines future research directions toward scalable manufacturing, environmental stability, and multifunctional integration for the real-world deployment of smart sensing and actuation systems.

Spin waves (SWs), an ultra-low power magnetic excitation in ferro or antiferromagnetic media, have tremendous potential as transport less data carriers for post-CMOS technology using their wave interference properties. The concept of magnon interference originates from optical interference, resulting in a historical taboo of maintaining an identical wavevector for magnon interference-based devices. This makes the attainment of on-chip design reconfigurability challenging owing to the difficulty in phase tuning via external fields. Breaking the taboo, this study explores a novel technique to systematically control magnon interference using asymmetric wavevectors from two different SW modes (magnetostatic surface SWs and backward volume magnetostatic SWs) in a microstructured yttrium iron garnet crossbar. Using this system, we demonstrate phase reconfigurability in the interference pattern by modulating the thermal landscape, modifying the dispersion of the interfering SW modes. Thus, we manifest that such a tunable interference can be used to implement reconfigurable logic gates operating between the XNOR and XOR modes by using symmetric and asymmetric interference, respectively.

We present a dynamic spin wave (SW) modulation technique using direct current (DC) to manipulate the magnetic properties of an ultralow-damping Y₃Fe₅O₁₂ thin film. The microwave excitation and detection technique with two coplanar waveguide antenna arrangements on the Y₃Fe₅O₁₂ (YIG) surface is used to characterize the SW. An additional platinum (Pt) stripe connected to a current source is integrated between the coplanar waveguide pair to demonstrate the SW resonant frequency and amplitude modulation by current induction. We selected a Pt stripe due to its significantly lower spin wave absorption property. The application of current through the Pt stripe generates local joule heating that modifies the magnetic properties of the YIG film. Temperature variation through local heating modifies the saturation magnetization of the YIG film, which, in turn, modulates the SW frequency. Moreover, the amplitude of the SW spectra is found to be tuned by the current amplitude. This phenomenon is mainly described by magnon–magnon scattering induced by the spin Seebeck effect in the case of local heating. Furthermore, the group velocity of the proposed device is also found to be responsive to the current, which has been explained by both magnon–magnon and magnon-phonon scattering.

Spin waves (SWs) have tremendous application potential in wave-based computation utilizing a broad frequency spectrum spanning from the gigahertz-to-terahertz ranges. Like optical and other electromagnetic waves, SWs also promise to usher in a new era of parallel data processing with low-power consumption without Joule heating. However, this potential is undermined by the lack of investigation on multichannel networking and operation on single chips under a uniform bias magnetic field. This study proposes a multifrequency SW propagation based on shape anisotropy in microstructured rectangular waveguides made of yttrium iron garnet (YIG). The width-dependent transmission properties of magnetostatic surface SWs in the YIG waveguides were experimentally demonstrated. We revealed that the smaller width of the waveguide results in lower SWs frequency due to the demagnetizing field along the width direction. Multifrequency SW propagation was demonstrated in a device where three waveguides with widths of 10, 20, and $100~\mu \text{m}$ were connected to the common antennas. SWs propagation with the frequencies of 1.98, 2.11, and 2.18 GHz have been transmitted under a uniform bias magnetic field. Furthermore, we investigated SWs transmission in a device where three waveguides with different widths were interconnected at their ends and under one side of the antenna. We observed that the interconnected waveguides result in a single resonant frequency with flat band transmission because the whole waveguide structure is considered a single magnetic body. The results presented here provide guidelines for complex networks in frequency-division multiplexing operation.

Magnonics, an emerging research field that uses the quanta of spin waves as data carriers, has a potential to dominate the post-CMOS era owing to its intrinsic property of ultra-low power operation. Spin waves can be manipulated by a wide range of parameters; thus, they are suitable for sensing applications in a wide range of physical fields. In this study, we designed a highly sensitive, simple structure, and ultra-low power magnetic sensor using a simple CoFeB/Y₃Fe₅O₁₂ bilayer structure. We demonstrated that the CoFeB/Y₃Fe₅O₁₂ bilayer structure can create a sharp rejection band in its spin-wave transmission spectra. The lowest point of this strong rejection band allows the detection of a small frequency shift owing to the external magnetic field variation. Experimental observations revealed that such a bilayer magnetic sensor exhibits 20 MHz frequency shifts upon the application of an external magnetic field of 0.5 mT. Considering the lowest full width half maximum, which is about 2 MHz, a sensitivity of 10^–2 mT order can be experimentally achieved. Furthermore, the higher sensitivity in the order of 10^–6 T (µT) has been demonstrated using the sharp edge of the rejection band of the CoFeB/Y₃Fe₅O₁₂ bilayer device. A Y-shaped spin waves interference device with two input arms consisting of CoFeB/Y₃Fe₅O₁₂ and Y₃Fe₅O₁₂ has been theoretically investigated. We proposed that such a structure can demonstrate a magnetic sensitivity in the range of $${10}^{-9}$$10 - 9 T (nT) at room temperature. The sensitivity of the sensor can be further enhanced by tuning the width of the CoFeB metal stripe.