Research Projects

This project aims to design and characterize exchange-biased magnetic multilayers integrating Heusler alloy-based synthetic antiferromagnetic (SAF) structures, with an emphasis on enhancing magnon-magnon coupling. These systems are fundamental to spintronic device applications, where high magnetic and thermal stability is imperative. By leveraging the high spin polarization and tunable properties of Heusler alloys, coupled with dynamic magnon interactions, the study explores novel mechanisms for improving magneto-thermal resilience. The methodology combines advanced thin-film deposition techniques with precise magnetic characterization using magnetometry, ferromagnetic resonance. Results will guide the design of multilayers that exhibit stable exchange bias, strong spin coherence, and temperature endurance essential for scalable and energy-efficient spintronic technologies. Spin waves or magnons are suggested to build spin-torque nano-oscillators with terahertz (THz) ultrahigh frequency signal or to be a new degree of freedom to encode information. Recent experiments show that the magnon excitations can be generated in crystalline AFMs at the THz frequency where difficulty in magnetization control is making the situation worse. In addition, with the miniaturization of devices such as magnetic random-access memories and magneto-resistive read heads, the switching field (HSW) increases rapidly due to demagnetizing field arising from the cell edge. In that order, to achieve the first goal, crystalline AFMs can be replaced by synthetic antiferromagnets (SAFs) which have the combined advantages of both high frequency of AFMs and easy detection of FMs but to achieve the second goal, it is very necessary for FM layers to have low coercivity (HC). This can be achieved with Heusler alloy- based SAF. These systems leverage the unique properties of Heusler alloys, such as high spin polarization and tunable magnetic properties, to engineer strong and controllable magnon interactions. The proposed study aims to develop magnetically and thermally stable exchange-biased multilayer systems utilizing Heusler alloy-based synthetic antiferromagnetic (SAF) configurations. These systems are critical for advancing spintronic applications, where high performance under thermal and magnetic fluctuations is required. A key focus is placed on exploring enhanced magnon-magnon coupling within these multilayers, a dynamic interaction hypothesized to strongly influence spin coherence and thermal robustness. This research involves precise thin-film fabrication of SAF structures based on high-spin-polarized Heusler compounds, followed by in-depth characterization using advanced magnetometry and ferromagnetic resonance techniques. By systematically varying layer compositions and exchange coupling strengths, the project will investigate the interplay between material structure, magnon dynamics, and field stability. Expected outcomes include the identification of design principles for multilayer systems with optimized exchange bias and spin wave behavior, paving the way for their integration into resilient and energy-efficient spintronic devices. In SAFs, typically composed of two ferromagnetic layers separated by a non-magnetic spacer, two principal magnon modes emerge: the acoustic (in-phase) and optic (out-of-phase) modes. Magnon-magnon coupling refers to the interaction between these modes, which can be dramatically enhanced by Interlayer exchange coupling (J_(IEC) less than 0), dynamical dipolar interactions, symmetry breaking within the multilayer stack either by structural asymmetry or bias field tuning. When these conditions are met, the resonance spectra of the system display mode splitting and large anti-crossing gaps, which are hallmarks of strong or even ultrastrong magnon-magnon coupling. The strength of this coupling can be further enhanced by increasing the wave number of the excited spin waves or by optimizing the layer thickness and number.