Physical Science and Technology, King Abdullah Univ. of Sci. and Tech. Saudi Arabia

Abstract：
A new type of graphene material, three-dimensional flexible and conductive interconnected graphene networks (graphene foam ) has been synthesized using chemical vapour deposition with Ni foam as a template [1].
This material exhibit interesting properties and has found a number a applications, such as, flexible lithium ion batteries with ultrafast charge and discharge rates [2], electromagnetic interference(EMI) shielding materials [3].
In this work we presents the study of magneto-transport properties of the three-dimensional flexible and conductive interconnected graphene networks.
The temperature dependent resistivity of the graphene networks of dimension of 1x3x10 mm  was measured with four probe techniques in the temperture range of 1.8 K to 300 K. With decreasing temperature from 300K, the resistance increases monotonically till a maximum at 23 K, in which resistance increased about 50%. With further decreasing temperture form 23K to 1.8K, the resistance decreases linearly.
The magnetoresistance (MR) as a function of applied magnetic field was measured in different configurations: a) magnetic field being perpendicular to both the foam plane and the current; b) magnetic field being parallel the foam plane and the current;  and c) magnetic field being perpendicular to the current, but angle between the magnetic field and normal direction of the foam plane being changed.
As large as 300% of magnetoresistance was observed in two both configurations of (a) and (b). More importantly, the observed MR is not only very large, but also nearly temperture independent over the whole temperature range. This characteristics of the MR qualifies the graphene foam as a potential material candidate for the field sensors operating in both wide temperture range and with magnetic field range. Another very interesting observation is that an anisotropic MR was observed in the third configuration, which was not expected for three dimensional nature of the material. All the above observation indicate that this novel material opens a wide possibility not only for applications but also for the fundamental research. 

References:
(1) Z.P. Chen,W.C. Ren, L.B. Gao, B.L. Liu, S. F. Pei and H. M.  Cheng, Nature Materials 10, 424 (2011).
(2) N. Lia, Z. P. Chen, W.C. Ren,  F. Li and  H. M. Cheng PNAS 109, 17360–17365 (2012).
(3)  Z. P. Chen , C. Xu , C.Q.  Ma , W. C. Ren and H.M. Cheng  Adv. Mater. 2013, 25, 1296–1300 (2013).

联系人：韩秀峰（9268）