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BEGIN:VEVENT
DTSTAMP:20261020T025115Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20110915T200000Z
DTEND:20110915T210000Z
UID:event848@bu.edu
URL:http://physics.bu.edu/internal/events/show/848
SUMMARY:Alex Kitt - The Effects of Strain on the Phonons in Graphene
DESCRIPTION:\nPart of the Preliminary Oral Exam.\n\nTitle: The Effects of S
	train on the Phonons in Graphene\n\n Examining Committee:&nbsp; Bennett Gol
	dberg\, Anna Swan\, Claudio Chamon\, Linda Doerrer (Chemistry)\n\n Abstract
	:\n Studying the effects of strain on the phonon modes in graphene allows a
	ccess to a rich variety of physics.&nbsp; These include the downshift of th
	e zone center E2G optical phonon\, the origin of the high thermal conductiv
	ity of suspended graphene\, and the observation of pseudo magnetic fields.&
	nbsp; In all cases\, strain is induced by applying pressure to a graphene s
	ealed microchamber.&nbsp; Upon the application of pressure\, the graphene i
	s pushed into the hole and variable strain develops in the sheet.&nbsp; The
	 zone center E2G optical phonon energy has been measured with Raman spectro
	scopy as a function of pressure.&nbsp; The observed down shifts are fit to 
	a continuum model to determine the phonon energies dependence on biaxial st
	rain.&nbsp; This geometry will also allow the thermal conductivity to be me
	asured as a function of strain giving insight into the mechanism of heat co
	nduction in graphene.&nbsp; The damping of the out of plane acoustic phonon
	 is believed to be the reason that graphene&rsquo;s thermal conductivity de
	creases when it is supported [1].&nbsp; With the application of strain\, th
	is phonon mode should change from quadratic to linear near the gamma point\
	, lowering the density of states.&nbsp; If it is the main channel for heat 
	conduction\, this should drastically lower the thermal conductivity.&nbsp; 
	Finally\, it has been predicted that pressure applied to a triangular graph
	ene sealed microchambers should give rise to a tunable pseudo magnetic fiel
	d in graphene as high as 5 T for 14 MPa of pressure [2].&nbsp; This exotic 
	effect should manifest itself in anti-crossing behavior of the zone center 
	E2G phonon as it goes into resonance with selected Landau level transitions
	.&nbsp;&nbsp; The possibility of measuring this was Raman spectroscopy will
	 be discussed.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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