VP17-05: Understanding stability and behavior of Magnetic Tunnel Junction (MTJ) using Electron Spin Resonance (ESR)

The unique attributes of magnetic tunnel junctions (MTJs), stemming from their sandwich-like structure, enable them to have promising applications across diverse fields. MTJs are composed of two ferromagnetic electrode layers separated by a thin insulator, such as aluminum oxide. MTJs properties could be tuned by carefully selecting and designing the materials used for the ferromagnetic electrodes and the thickness of the insulating layer. Thermal stability refers to the MTJ's ability to maintain magnetization despite thermal fluctuations. This study examines the thermal stability of a molecular spintronic device utilizing a magnetic tunnel junction (MTJMSD) with varying insulator thicknesses. The device fabrication involves photolithography, thin film sputtering, and a molecule attachment process. Single-molecule magnet (SMM) is used to create a channel connecting the top and bottom electrodes on the exposed side edge of the MTJ. To investigate the impact of increasing temperature on the device, the samples are subjected to a gradual heating process. The temperature is raised in 20°C increments, starting from room temperature until reaching 190°C. To explore the temperature-dependent variances, the magnetic resonance of the device is measured utilizing Electron Spin Resonance (ESR) technique. Initially, the ESR measurement is conducted at room temperature, serving as the baseline reference. Following this, the devices are exposed to heat, and subsequent ESR measurements are taken to examine any alterations in the magnetic resonance properties induced by the temperature changes. This approach allows for the investigation of temperature-dependent differences in the device's characteristics. The findings reveal that MTJMSD with thinner insulator thickness exhibits superior thermal stability compared to devices with thicker insulators. This observation correlates directly with the effect of the molecule, as the MTJMSD with a thinner insulator experiences a pronounced impact from the molecule, resulting in strong coupling and heightened thermal stability. This study sheds light on the creation of thermally stable MTJMSD, which is imperative for achieving reliable and consistent device performance.