Electrically tunable thin-film inductors based on synthetic antiferromagnet cores

Abstract

The objective of this research is to demonstrate the feasibility of implementing electrically tunable on-chip inductors based on synthetic antiferromagnet (SAF) cores. This thin film magnetic core is made of a magnetic bi-layer antiferromagnetically coupled through a nonmagnetic spacer layer. An energy model is developed to investigate the magnetic behavior of this SAF structure by minimizing the magnetic energy of the system. The simulation results show that as a current passes through the SAF structure, its effective susceptibility can be varied over a wide range. SAF patterned structures (NiFe/Ru/NiFe) have been designed, fabricated, and tested. The measurement results for the susceptibility changes as a function of sheet current density and applied field have been discussed respectively. A tuning range (relative change in permeability) of 35 % can be achieved at 800Hz. By using these cores in on-chip inductors, it will be possible to electrically tune the inductance.