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Making graphene magnetic

Speaker: 
Irina V. Grigorieva (University of Manchester, UK)
Date: 
Thu, 16/08/2012 - 12:00pm to 1:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Event Type: 
Seminars

Abstract:

The possibility to induce magnetic response in graphene by introduction of defects has been generating much interest, as this would expand the already impressive list of its special properties and allow novel devices where charge and spin manipulation could be combined. In this talk I will review our recent experiments where we show that point defects in graphene – (i) fluorine adatoms in concentrations x gradually increasing to stoichiometric fluorographene CF_{x-1.0} and (ii) irradiation defects (vacancies) – carry magnetic moments with spin 1/2. Both types of defects lead to notable paramagnetism but no magnetic ordering could be detected down to liquid helium temperatures. The induced paramagnetism dominates graphene’s low-temperature magnetic properties, despite the fact that maximum response we could achieve was limited to one moment per approximately 1000 carbon atoms. This limitation is explained by clustering of adatoms and, for the case of vacancies, by the requirement to keep graphene’s structural stability. Our work clarifies the controversial issue of graphene’s magnetism and sets limits for other graphitic compounds.

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