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DTSTAMP:20260813T020321Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20080215T170000Z
DTEND:20080215T180000Z
UID:event239@bu.edu
URL:http://physics.bu.edu/internal/events/show/239
SUMMARY:Quantum Magnets under Pressure
DESCRIPTION:Featuring Bruce Normand\, ETH Zurich\, Switzerland\nHosted by: 
	Claudio Chamon\n\nPart of the Biophysics/Condensed Matter Seminar Series.\n
	\nAbstract: In recent inelestic neutron scattering experiments\, Rueegg et 
	al. investigated the pressure-induced magnetic quantum phase transition in 
	the dimer spin system TlCuCl_3. The triplet excitation spectra were measure
	d on both sides of the quantum critical point\, and the emergence of a well
	-defined\, massive amplitude mode\, or longitudinal excitation of the magne
	tic moment\, demonstrated in the ordered phase. We discuss the pressure-ind
	uced magnetic quantum phase transition and compare this with its field-indu
	ced counterpart. The splitting of the excitation mode gaps suggests a finit
	e exchange anisotropy\, which is shown to be of easy-plane type; its quasi-
	uniaxial nature is responsible for the presence of one effectively massless
	 spin-wave mode in the ordered phase. Also fitted is the pressure-dependenc
	e of the interdimer coupling parameters required to explain the vanishing o
	f the gap. The longitudinal mode arises naturally at the quantum phase tran
	sition\, and is reproduced with no additional parameters.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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