Surface Roughness-Dependent Magnetic Properties in CoFeB Thin Films for Flexible Sensors

This study explores the magnetic characteristics of CoFeB-based magnetic thin films on flexible substrates, focusing on how surface roughness affects their magnetic properties. By examining substrates such as PDMS, PI, and PEN, we observed that increased surface roughness leads to higher coercivity, enhancing sensor stability by restricting domain wall movement and resisting magnetic disturbances. The remanent magnetization to saturation magnetization ratio values for the flexible substrate were slightly lower, ranging from 72 to 60 percent of the rigid Si/SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> substrate values. Still, the difference was within a manageable range. Moreover, the 4.6 - to 10.2-fold increase in coercivity on flexible substrates compared to Si/SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>substrates compensates for the reduced remanent magnetization to saturation magnetization ratio, ensuring reliable performance in magnetic sensor applications. These findings highlight the potential for optimizing flexible magnetic sensors through surface engineering or multilayer designs, contributing to developing next-generation wearable and adaptable sensor devices.