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.