Investigations for magnetoresistance of ultralow-hole-density monolayer epitaxial graphene grown on SiC systems
Chiashain Chuang1,2*, Chieh-Wen Liu2,3, 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,
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