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# Eric D. Isaacs <isaacs@lucent.com>
# requesting 4 days, at minimum=3 days
# beamline 33BM, "X-ray diffraction search for charge ordering in La2CuO4"
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# top:/home/www/beamtime-requests/req00305.txt
# UNICAT Member Beam Time Request  #305
# created Mon Nov 18 10:31:53 CST 2002
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beamline:
	33BM

collaboration:
	Yes

collaborator+Paul:
	on

contact:
	isaacs@lucent.com

days:
	4

description:
	The competition between the insulating states and superconductivity is a key feature of the high-TC problem, yet the character of the insulating state remains elusive.  Striped density waves are one of the primary candidates for the insulating ground state.  However, direct and unambiguous x-ray observation of any charge ordered state in the cuprates remains an outstanding problem in the high-TC community.  In the past year, quasi-elastic Raman scattering data published in Science has provided some of the most compelling evidence for a pinned density wave in the quasi one-dimensional ladder compound Sr14Cu24O41.  Very recently, unpublished results have shown a similar fingerprint of pinned charge density waves in the world's first untwined crystals of La2-xSrxCuO4. The keys to this finding, were the very low doping (x~0.01) and the fact that these samples were untwined.
	We propose an x-ray diffraction experiment in untwined La2-xSrxCuO2, the same crystals used in the above-mentioned Raman measurements, in order to search for charge ordering.  The most serious challenge to such an observation is that doped holes only comprise a very small fraction of the total number of electrons per unit cell so that the ordering wavevector will be small and the scattering signal weak.

equipment+required:
	displex, analyzer

experiment:
	X-ray diffraction search for charge ordering in La2CuO4

foreign+nationals:
	

hazards:
	none

minimumdays:
	3

name:
	Eric D. Isaacs

new+request:
	on

nonmembers:
	Girsh Blumberg, Bell Labs
	Eric Isaacs, Bell Labs

unacceptable+dates:
	none


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