Epitaxial Graphene Sensors for Detection of Small Magnetic Moments

摘要

Micron-sized Hall sensors made of epitaxial graphene grown on $4H!!-!!{rm SiC}(0001)$ have been fabricated and studied at room temperature using transport and noise spectrum measurements. We report detection of 1- $mu{rm m}$ Dynal bead with the magnetic moment of $sim 4times 10^{8} mu_{rm B}$, using a 2-$mu{rm m}$ epitaxial graphene device. A phase-sensitive AC-DC Hall magnetometry method was used to reliably detect the bead with a relatively large response of $V_{x}^{rm AC}sim 7 mu{rm V}$ . Bead positioning was performed using a nanomanipulator inside of the FIB system. Long-term effect of the small dose of e-beam irradiation $(sim 4times 10^{14} {rm e/cm}^{2})$ on the performance of graphene Hall devices is reported.