Investigations for magnetoresistance of ultralow-hole-density monolayer epitaxial graphene grown on SiC systems

Chiashain Chuang^1,2*, Chieh-Wen Liu^2,3, Yanfei Yang², Wei-Ren Syong⁴, Chi-Te Liang⁴, Randolph E. Elmquist²

¹Department of Electronic Engineering, Chung Yuan Christian University, Taoyuan City, Taiwan
²Fundamental Electrical Measurements Group, National Institute of Standard and Technology, Maryland, USA
³Department of Physics, Case Western Reserve University, Cleveland, USA
⁴Department of Physics, National Taiwan University, Taipei, USA

* Presenter:Chiashain Chuang, email:chiashain@gmail.com

In this talk, I concentrate on detailed measurements on ultralow-density p-type monolayer epitaxial graphene, which has yet to be extensively studied. The measured resistivity ρxx shows insulating behavior in the sense that ρxx decreases with increasing temperature T over a wide range of T (1.5 K ≤ T ≤ 300 K). The crossover from negative magnetoresistivity (MR) to positive magnetoresistivity at T = 40 K in the low-field regime is ascribed to a transition from low-T quantum transport to high-T classical transport. For T ≥ 120 K, the measured positive MR ratio [ρxx(B) − ρxx(B = 0)]/ρxx(B = 0) at B = 2 T decreases with increasing T, but the positive MR persists up to room temperature. Our experimental results suggest that the large MR ratio (~100% at B = 9 T) is an intrinsic property of ultralow-charge-density graphene, regardless of the carrier type. This effect may find applications in magnetic sensors and magnetoresistance devices.

Keywords: epitaxial graphene, resistance standard, magnetoresistance, PMOS, quantum hall