BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//RLASKEY//CALENDEROUS//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260912T123837Z
LAST-MODIFIED:20201109T211704Z
DTSTART:20201113T190000Z
DTEND:20201113T200000Z
UID:event2369@bu.edu
URL:http://physics.bu.edu/internal/events/show/2369
SUMMARY:New aspects of deconfined quantum criticality
DESCRIPTION:Featuring Bowen Zhao\, Boston University\, Physics Department\n
	Poster: http://physics.bu.edu/internal//files/download/Zhao-Bowen.pdf\n\nPa
	rt of the Preliminary Oral Exam.\n\nQuantum phase transitions beyond the La
	ndau-Ginzburg-Wilson paradigm based on order parameters are at the forefron
	t of modern condensed matter physics. A specific example is the transition 
	between an antiferromagnet (AFM) and a dimerized valence-bond solid (VBS) i
	n 2 space dimension\, where it has been argued that the critical behavior s
	hould be described by emergent fractionalized degrees of freedom (spinons) 
	rather than the order parameters of the two phases [1]. Many studies have b
	een carried out and much progresses has been made since the original idea w
	as proposed. However\, many new issues and controversies have also arisen\,
	 e.g.\, the possibility of a weakly first-order transitions rather than a c
	ontinuous one and possible emergent higher symmetries at the transition. In
	 this talk I will address such issues based on lattice models and quantum M
	onte Carlo simulations. We proposed and simulated [2] an effective model de
	scribing a first-order transition between the AFM and a two-fold degenerate
	 plaquette VBS and found that the system develops a higher symmetry\, O(4)\
	, from the O(3) and Z2 symmetries of the order parameters. Such emergent sy
	mmetry had not been expected at a first-order transition but our results sh
	ow that it appears at least up the largest accessible length scales (~100 l
	attice spacing). Such an unusual transition may be realizable in the 2D Sha
	stry-Sutherland compound SrCu2(BO3)2 and our model was used to interpret th
	ermodynamic properties of this material in a recent experiment [3]. I will 
	also discuss a perturbation of the deconfined critical point that leads to 
	a new helical VBS phase [4]\, which had not been considered within existing
	 theories of deconfined quantum criticality. \n\n[1] Senthil\, T.\, Vishwan
	ath\, A.\, Balents\, L.\, Sachdev\, S. and Fisher\, M.P.\, Science\, 303\, 
	1490 (2004) \n\n[2] Zhao\, B.\, Weinberg\, P. and Sandvik\, A.W.\, Nat. Phy
	s.\, 15\, 678 (2019) \n\n[3] Guo\, J.\, Sun\, G.\, Zhao\, B.\, Wang\, L.\, 
	Hong\, W.\, Sidorov\, V.A.\, Ma\, N.\, Wu\, Q.\, Li\, S.\, Meng\, Z.Y. and 
	Sandvik\, A.W.\, Phys. Rev. Letters\, 124\, 206602 (2020) \n\n[4] Zhao\, B.
	\, Takahashi\, J. and Sandvik\, A.W.\, arXiv:2005.10184 (2020) (to appear i
	n Phys. Rev. Lett.)\n\n--------\n\nLink: https://bostonu.zoom.us/j/97518974
	755?pwd=M1hHQlcxaGtaeWxnMGE1R1prNDEvdz09\n\nMeeting ID: 975 1897 4755; \nPa
	sscode: 940529.
LOCATION: \, \, 
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR