Condensed Matter Physics Seminar

Speaker: Erik Henriksen, Washington University, St. Louis

Title: Charge-Doping a Mott Insulator via Graphene Hetero­structures

Refreshments available at 3:45 pm.

Date: Mon, 22 Oct 2018, 4:10 pm – 5:10 pm
Type: Seminar
Location: 1400 BPS Bldg.

Abstract:
a-RuCl₃ is a layered anti­ferro­magnetic Mott insula­tor recent­ly found to host a Kitaev quan­tum spin liquid, and notably there has been a claim for non-Abeli­an trans­port seen in a quan­tized ther­mal Hall conduc­tance experi­ment. Seek­ing a means to ac­cess this physics using elec­tronic approach­es, we have begun explor­ing this materi­al by ex­folia­tion à la graphene to make meso­scale de­vices. In par­ticular we have in­corpora­ted RuCl₃ flakes into so-called van der Waals hetero­struc­tures. While the elec­trical con­duc­tivity of RuCl₃ alone is seen to drop like a rock with de­creas­ing tem­pera­ture, when placed in close proxim­ity to mono­layer graphene we ob­serve an anom­alous­ly high con­ductiv­ity through the com­bined system. More­over, we find evi­dence of multi­band trans­port and clear sig­na­tures of a ‘criti­cal resis­tivity’ due to elec­tron scat­tering by spin fluc­tua­tions near a mag­netic phase tran­sition. All of these ef­fects vary with an ap­plied gate volt­age. It appears that proxim­ity to graphene in­duces a charge trans­fer to RuCl₃ that is sensi­tive to and per­haps control­lable by an ex­ter­nal volt­age.