Magnetic logic inverter from crossed structures of defect-free graphene with large unsaturated room temperature negative magnetoresistance

Introducing defects into graphene has been widely utilized to realize the negative magnetoresistanee(MR)effect in graphene.However,the reported graphene negative MR exhibits only^10%under 10 T at room temperature to date,which extremely limits the resolution of future spintronics devices.Moreover,intentional defect introduction can also cause unintentional degradation in graphene's intrinsic properties.In this paper,we report a magnetic logic inverter based on a crossed structure of defect-free graphene,resulting in a substantial gain of 4.81 mV/T while exhibiting room temperature operation.This crossed structure of graphene shows large unsaturated room temperature negative MR with an enhancement of up to 1,000%at 9 T.A transition behavior between negative and positive MR is observed in this crossed structure and the transition temperature can be tuned by a ratio of the conductivity between in-plane and out-of-plane transport.Our results open an intriguing path for future two-dimensional spintronics device applications.

Large unsaturated room temperature negative magnetoresistance in graphene foam composite for wearable and flexible magnetoelectronics

Room temperature positive magnetoresistance(PMR)in graphene is a conventional phenomenon but we observed large negative magnetoresistance(NMR)in graphene foam(GF)/polydimethylsiloxane(GF/PDMS)at room-mperature for the first time.The largest NMR^35%was detected at 250 K,while PMR is observed below 200 K.Furthermore,PMR at all temperatures is observed in regular GF specimens,hence,NMR is the result of the infiltration with the electrically insulating polymer.Forward interference and wavefunction shrinkage model has been employed to understand the transport mechanism in GF/PDMS.A critical temperature^224 Kfor switching between NMR and PMR is observed at the crystallization-mperature of PDMS,suggesti ng a cha nge in polymer chai n con formation may be a major reason leading to NMR in GF/PDMS specimens thus role of mechanical properties of PDMS in NMR cannot be ignored and observed locally via specially;resolved atomic force microscopy.In addition,storage modulus and heat flow study shows similar transition temperature(~200 K)of NMR to PMR and provide an evidence of mechanical stable specimens.As is known,large,tunable,and unsaturated NMR at room temperature is very useful for future facile practical shapeable magnetoelectronic devices.