Alexey Berdyugin1,2,Na Xin1,James Lourembam1,Piranavan Kumaravadivel1,Alexander Kazantsev1,Zefei Wu1,Ciaran Mullan1,Julien Barrier1,Alexandra Geim1,Irina Grigorieva1,Artem Mishchenko1,Alessandro Principi1,Vladimir Falko1,Leonid Ponomarenko3,Andre Geim1
The University of Manchester1,National University of Singapore2,The University of Lancaster3
Alexey Berdyugin1,2,Na Xin1,James Lourembam1,Piranavan Kumaravadivel1,Alexander Kazantsev1,Zefei Wu1,Ciaran Mullan1,Julien Barrier1,Alexandra Geim1,Irina Grigorieva1,Artem Mishchenko1,Alessandro Principi1,Vladimir Falko1,Leonid Ponomarenko3,Andre Geim1
The University of Manchester1,National University of Singapore2,The University of Lancaster3
The most recognizable feature of graphene’s electronic spectrum is its Dirac point, around which interesting phenomena tend to cluster. At low temperatures, the intrinsic behaviour in this regime is often obscured by charge inhomogeneity but thermal excitations can overcome the disorder at elevated temperatures and create an electron–hole plasma of Dirac fermions. The Dirac plasma has been found to exhibit unusual properties, including quantum-critical scattering and hydrodynamic flow. However, little is known about the plasma’s behaviour in magnetic fields. Here we report magnetotransport in this quantum-critical regime. In low fields, the plasma exhibits giant parabolic magnetoresistivity reaching more than 100 per cent in a magnetic field of 0.1 tesla at room temperature. This is orders-of-magnitude higher than magnetoresistivity found in any other system at such temperatures. We show that this behaviour is unique to monolayer graphene, being underpinned by its massless spectrum and ultrahigh mobility, despite frequent (Planckian limit) scattering. With the onset of Landau quantization in a magnetic field of a few tesla, where the electron–hole plasma resides entirely on the zeroth Landau level, giant linear magnetoresistivity emerges. It is nearly independent of temperature and can be suppressed by proximity screening, indicating a many-body origin. Clear parallels with magnetotransport in strange metals and so-called quantum linear magnetoresistance predicted for Weyl metals offer an interesting opportunity to further explore relevant physics using this well defined quantum-critical two-dimensional system.