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VERSION:2.0
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BEGIN:VEVENT
DTSTAMP:20260827T002225Z
LAST-MODIFIED:20171108T154124Z
DTSTART:20171110T170000Z
DTEND:20171110T183000Z
UID:event1819@bu.edu
URL:http://physics.bu.edu/internal/events/show/1819
SUMMARY:"Shining Coherent X-rays on Quantum Materials"
DESCRIPTION:Featuring Yue Cao\, Brookhaven National Laboratory\nHosted by: 
	Karl Ludwig\n\nPart of the Biophysics/Condensed Matter Seminar Series.\n\nS
	ymmetry breaking and recovery in condensed matter systems are closely relat
	ed with exotic properties of these materials – superconductivity\, magnet
	ism\, ferroelectricity\, etc. Recent and upcoming implementations of cohere
	nt X-ray techniques at synchrotrons and free electron lasers open the door 
	to novel experimental opportunities to directly visualize the symmetry chan
	ges in quantum materials. In this talk I will discuss two such efforts to s
	tudy doped Mott insulators with layered perovskite structures.\n\nWe have p
	ushed Bragg Coherent Diffractive Imaging (BCDI) into the cryogenic regime w
	here most phase transitions in quantum materials reside. Utilizing coherent
	 photons at 34-ID-C beamline of the Advanced Photon Source\, we studied the
	 low-temperature phases in the original cuprate superconductor La2-xBaxCuO4
	. These phases break the local four-fold rotational symmetry of the high te
	mperature tetragonal (HTT) structure. Our preliminary data suggests the gla
	ssy nature of the low-temperature-orthorhombic (LTO) phase [1]. These obser
	vations put stringent constraint on the theoretical descriptions regarding 
	the nature of charge order [2] and its relation with superconductivity.\n\n
	Recently we demonstrated time-resolved Resonant Inelastic X-ray Scattering 
	(tr-RIXS) for the first time at LCLS to observe the temporal evolution of c
	ollective excitations in Sr2IrO4 [3]. At the destruction of long-range anti
	ferromagnetic order under controlled conditions\, tr-RIXS provides definiti
	ve evidence of transient antiferromagnetic correlations recovering over a f
	ew picoseconds\, while the long-range order is not restored over a pump-flu
	ence-dependent time scale over hundreds of picoseconds.\n\nLooking forward\
	, many quantum materials have been discovered to possess desired properties
	 in the material science and engineering. Meanwhile quantum effects have be
	en found important in many functional materials. I will briefly discuss how
	 these new X-ray methods will be applied to interrogate the structural and 
	electronic properties in the materials.\n\n\nReference\n\n[1] Y. Cao\, T. A
	ssefa\, I. K. Robinson et al.\, in preparation (2017).\n[2] X. M. Chen et a
	l.\, Phys. Rev. Lett. 117\, 167001 (2016); \nV. Thampy et al.\, Phys. Rev. 
	B 95\, 241111(R) (2017).\n[3] M. P. M. Dean*\, Y. Cao* et al.\, Nat. Mater.
	 15\, 601–605 (2016).
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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