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DTSTAMP:20260728T014624Z
LAST-MODIFIED:20190715T130320Z
DTSTART:20190802T160000Z
DTEND:20190802T170000Z
UID:event2155@bu.edu
URL:http://physics.bu.edu/internal/events/show/2155
SUMMARY:Freestanding 2D Oxide Perovskites --- a new playground for strongly
	 correlated 2D phases
DESCRIPTION:Featuring Yuefeng Nie\, Nanjing University\nHosted by: Wanzheng
	 Hu\n\nPart of the Biophysics/Condensed Matter Seminar Series.\n\nTwo-dimen
	sional (2D) materials such as graphene and transition metal dichalcogenides
	 (TMD) have demonstrated how the new electronic phases emerge when a bulk c
	rystal is thinned down to a mono-layer. As transition metal oxide perovskit
	es host a variety of correlated phases\, realizing the analogs with transit
	ion metal oxide perovskite materials would open the door to a rich spectrum
	 of exotic 2D correlated phases that have not yet been explored. Here we re
	port on the fabrication of freestanding perovskite films with high crystall
	ine quality down to a single unit cell[1]. Using the recently developed met
	hod based on water-soluble Sr3Al2O6 as the sacrificial buffer layer[2\,3] w
	e synthesize freestanding SrTiO3 and BiFeO3 ultrathin films by reactive mol
	ecular beam epitaxy (MBE) and transfer them to different substrates such as
	 crystalline silicon wafers and holey carbon films. We find that freestandi
	ng BiFeO3 films exhibit an unexpected giant tetragonality and polarization 
	when approaching the ultimate 2D limit. Our results demonstrate the absence
	 of critical thickness for stabilizing the crystalline order in the freesta
	nding ultrathin oxide films. The ability to synthesize and transfer crystal
	line freestanding perovskite films without thickness limitation onto any de
	sired substrate opens a new field for the 2D correlated electronic phases a
	nd interfacial phenomena that technically have not yet been accessible. \n\
	nIn this talk\, I will also present our recent works on the atomically prec
	ise engineering of the crystalline and electronic structure of titanates[4]
	 and iridates[5\,6] by a combination of oxide MBE and in situ angle-resolve
	d photoemission spectroscopy (ARPES). \n\n[1] D.X. Ji\, et al. Nature 570 8
	7–90 (2019)\n[2] D. Lu\, et al.\, Nat. Mater. 15\, 1255 (2016)\n[3] S. S.
	 Hong\, et al. Sci. Adv. 3\, eaao5173 (2017)\n[4] H.Y. Sun\, et al.\, Nat. 
	Commun. 9.1\, 2965 (2018)\n[5] Y.F. Nie\, et al. Phys. Rev. Lett. 114\, 016
	401 (2015)\n[6] W. Guo\, et al. in preparation
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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