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BEGIN:VEVENT
DTSTAMP:20260815T222805Z
LAST-MODIFIED:20210209T190442Z
DTSTART:20210212T200000Z
DTEND:20210212T210000Z
UID:event2401@bu.edu
URL:http://physics.bu.edu/internal/events/show/2401
SUMMARY:Mechanism for Superconductivity and Competing Excitonic Order in Ho
	neycomb Superlattices
DESCRIPTION:Featuring Julian Ingham\, Boston University\, Physics Departmen
	t\n\nPart of the Preliminary Oral Exam.\n\nHoneycomb superlattices — peri
	odic potential wells with the same symmetries as graphene but in which the 
	lattice spacing and potential profile can be tuned experimentally — have 
	attracted immense interest in recent years\, in particular in the context o
	f Moire and semiconductor heterostructures. I will explain how these materi
	als can realize a new mechanism for superconductivity\, which arises due to
	 the presence of a winding number in the electron wavefunction. The winding
	 number of the Dirac fermion causes destructive interference between states
	 with opposite momenta\, leading to the novel effect whereby electrons can 
	partially avoid the Coulomb repulsion by forming Cooper pairs. This gives r
	ise to an effective pairing attraction\, which is enhanced by doping due to
	 an antiscreening effect\, eventually leading to superconductivity. In syst
	ems where the superlattice is tuned to flatten the bands\, the effective at
	traction gives rise to an excitonic insulating order which competes with su
	perconductivity. The resulting phase diagram contains several phenomenologi
	cally novel states\, and the effects of Rashba and intrinsic spin orbit on 
	the phase diagram are discussed.
LOCATION: \, \, 
STATUS:CONFIRMED
CLASS:PUBLIC
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