#
# top.uni.aps.anl.gov:/home/www/beamtime-requests/req00226.txt
# UNICAT Member Beam Time Request  #226

# created Sun Dec 02 21:58:22 CST 2001
#
beamline:
	33ID

collaboration:
	No

contact:
	mvholt@uiuc.edu

days:
	3

description:
	The layered LSMO manganites  undergo both a paramagnetic to 
	ferromagnetic and metal to insulator phase transition as a function 
	of temperature, magnetic field, and doping - resulting in a rich and 
	poorly understood phase diagram.  Recent X-ray and neutron scattering 
	studies have revealed anomalous static diffuse scattering in the 
	paramagnetic phase, disappearing abruptly at the transition for 
	x=0.4.  This is attributed to polaron 'melting' (sudden charge 
	delocalization) following a disordered stripe model.  As such it is 
	expected to persist at low temperatures in the antiferromagnetic 
	x=0.44 system, and is not predicted for x=0.34 system. The planned 
	experiment is to measure the diffuse scattering over a wide 
	range in k space at a few points above and below the transition 
	temperature for samples prepared at x = 0.34, 0.4, and 0.44.  A 
	simple comparison of these results should shed light on the nature 
	of the diffuse scattering anomaly and its relation to the CMR 
	transition.

equipment+required:
	displex, diffractometer

experiment:
	Diffuse scattering in colossal magnetoresistive manganite La(2-2x)Sr(1+2x)Mn2O7

foreign+nationals:
	Dr. Zhong Quan Ma

hazards:
	cryogenic - a closed cycle He displex will be used

minimumdays:
	3

name:
	Martin Holt

new+request:
	on

nonmembers:
	

unacceptable+dates:
	


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