Unusual properties of graphene

(MainsGS3: Science and Technology- developments and their applications and effects in everyday life.)

Context:

• The 21st century seems set to become the age of graphene, a recently discovered material made from honeycomb sheets of carbon just one atom thick.
• Researchers in the UK, led by Nobel laureate Andre Geim, have discovered another property of graphene which displays an anomalous giant magnetoresistance (GMR) at room temperature.

About graphene:

• It is a two-dimensional form (allotrope) of carbon that consists of a single layer of carbon atoms arranged in a hexagonal lattice. 
• Graphene has been described as wondrous stuff — of being the strongest material ever tested, almost 300 times stronger than steel. 
• It is also the best heat- and electricity-conducting material to be discovered.
•  It could also become a valuable aid in filtering water and researchers from Australia announced recently that they used a graphene-based product to make a water filter that can make highly-polluted sea water drinkable after just one pass.

About magnetoresistance:

• GMR is the result of the electrical resistance of a conductor being affected by magnetic fields in adjacent materials. 
• It is used in harddisk drives and magnetoresistive RAM in computers, biosensors, automotive sensors, microelectromechanical systems, and medical imagers.
• GMR-based devices are particularly used to sense magnetic fields. 
• The new study has found that a graphene-based device, unlike conventional counterparts, wouldn’t need to be cooled to a very low temperature to sense these fields.

Higher magnetoresistance:

• The magnetoresistance observed in the graphene-based device was almost 100-times higher than that observed in other known semimetals in this magnetic field range.
• The effect is due to the way electrons in the conductor scatter off electrons in the ferromagnets depending on the orientation of the latter’s spin, which is affected by the direction of the magnetic field.
• Conventional GMR devices are cooled to low temperatures to suppress the kinetic energy of their constituent particles, keeping them from deflecting the electrons moving past them but in graphene, the researchers found this suppression unnecessary.

Other uses:

• Graphene, a form of carbon and a super-strong, ultra-light material discovered in 2004, enables flexible electronic components, enhances solar cell capacity, and promises to revolutionise batteries.
• Graphene’s further use to detect ALS (Amyotrophic Lateral Sclerosis- a progressive brain disorder for which there is currently “no objective diagnostic test.”
• ALS is characterised by rapid loss of motor neurons controlling skeletal muscles, leading to paralysis.