INVESTIGATION OF MAGNETOELECTRIC HETEROSTRUCTURE FOR FLEXIBLE ELECTRONICS

Abstract

The demand of the recent technology needs the development of multifunctional and flexible electronics devices. The flexible magnetic field sensors and memory devices find their wide applications in automotive industry, foldable smart phones, wearable health monitoring systems and light weight large data storage devices. The continuous efforts have been devoted for the development of such devices. Several approaches based on giant magnetoresistance, anisotropic magnetoresistance, giant magnetoimpedance and hall effect have already been utilized to develop flexible magnetic sensors. However, such sensors have several drawbacks such as huge expenses, large energy consumption and poor sensitivity. Hence, a cost effective and flexible magnetic sensor is required that can detect ultra-low magnetic field at room temperature with high sensitivity. In addition, the novel functional materials are being explored in memory devices in order to enhance the data storage capacity, low power consumption and functionality. The magnetoelectric (ME) heterostructure comprising the piezoelectric and magnetostrictive layers can be incorporated in multifunctional memory and magnetic field sensing devices. The magnetoelectric based magnetic field sensors are grabbing substantial attention owing to its low cost, noteworthy performance at room temperature, easy fabrication process and less energy consumption. In particular, thin film based magnetoelectric heterostructures are more promising for the on-chip integration of magnetoelectric devices and fabrication of microelectromechanical systems (MEMS). The introduction of lead-free piezoelectric aluminum nitride (AlN) thin film makes it compatible to complementary metaloxide- semiconductor (CMOS) technology and environmental friendly. Owing to the highest acoustic velocity, the AlN has been proved to be a best piezoelectric layer for acoustic MEMS based resonators. The ferromagnetic shape memory alloy (FSMA; Ni-Mn-In) introduces additional functionality to the fabricated devices as it shows magnetic field and temperature induced first order martensite transformation. During the structural transformation huge strain is generated and leads the strain mediated magnetoelectric coupling in AlN/Ni-Mn-In ME heterostructure. Therefore, the devices fabricated using highly magnetostrictive Ni-Mn-In layer can be tuned with external stimulus such as magnetic field, temperature and stress.