Abstract
A bulk sample of pressed graphene sheets was prepared under hydraulic pressure (similar to 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 (-140 kOe <= H <= 140 kOe) range. The magnetoresistance measured at a fixed temperature can be described by R(H, theta) = R(epsilon H-theta, 0) with epsilon(theta) =(cos(2)theta + gamma(-2) sin(2)theta)(1/2), where gamma is the mobility anisotropy constant and theta 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 (Delta mu). The magnetoresistance value at 140 kOe was related to the average mobility ( ) because of the condition Delta mu < . The carrier concentration remained constant and the temperature-dependent resistivity was proportional to the average mobility, as verified by Kohler's rule. Anisotropic dephasing length was deduced from weak localization observed at low temperatures.