Mobility controlled linear magnetoresistance with 3D anisotropy in a layered graphene pallet

A bulk sample of pressed graphene sheets was prepared under hydraulic pressure (∼150 MPa). The cross-section of the sample demonstrates a layered structure, which leads to 3D electrical transport properties with anisotropic mobility. The electrical transport properties of the sample were measured over a wide temperature (2-400 K) and magnetic field (-140kOe ≤ H ≤ 140kOe) range. The magnetoresistance measured at a fixed temperature can be described by R(H, ⊖) = R(ϵ _⊖ H, 0) with ϵ _⊖ = ( cos² ⊖ +υ^-2sin²⊖) ^1/2, where υ is the mobility anisotropy constant and ⊖ is the angle between the normal of the sample plane and the magnetic field. The large linear magnetoresistance (up to 36.9% at 400 K and 140 kOe) observed at high fields is ascribed to a classical magnetoresistance caused by mobility fluctuation (δμ). The magnetoresistance value at 140 kOe was related to the average mobility (〈μ〉) because of the condition δμ<〈μ〉. The carrier concentration remained constant and the temperature-dependent resistivity was proportional to the average mobility, as verified by Kohlers rule. Anisotropic dephasing length was deduced from weak localization observed at low temperatures.