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BEGIN:VEVENT
DTSTAMP:20261019T080622Z
LAST-MODIFIED:20151208T194801Z
DTSTART:20151209T160000Z
DTEND:20151209T170000Z
UID:event1522@bu.edu
URL:http://physics.bu.edu/internal/events/show/1522
SUMMARY:Valley-selective optical Stark effect in monolayer WS2
DESCRIPTION:Featuring Edbert J. Sie \, MIT\n\nPart of the Condensed Matter 
	Theory Seminar Series.\n\nSemiconductors that are atomically thin can exhib
	it novel optical properties beyond those encountered in the bulk compounds.
	 Monolayer transition metal dichalcogenides (TMDs) are leading examples of 
	such semiconductors that possess remarkable optical properties. They obey u
	nique selection rules where light with different circular polarization can 
	be used for selective photoexcitation at two electronic valleys. These vall
	eys constitute bandgaps that are normally locked in the same energy. Select
	ively varying their energies is of great interest for applications because 
	it offers a means to carry information in next-generation valleytronics. He
	re\, we demonstrate that the bandgaps at the two valleys can be shifted rel
	ative to each other by means of the optical Stark effect in a controllable 
	valley-selective manner. We will discuss the physics of this effect\, and d
	escribe the mechanism that leads to its valley-selectivity in monolayer TMD
	 tungsten disulfide (WS2). Finally\, by using this technique we propose to 
	realize a conceptually unique topological phase transition that can be made
	 valley-selective in this system. [Reference: E J Sie et al.\, Nature Mater
	ials 14\, 290 (2015)]
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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