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UID:69e03e404f0e2
DTSTAMP:20260415T214120
DTSTART:20140217T113000
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URL:https://murmitoyen.com/events/vanille/udem/detail/355440
LOCATION:Université de Montréal - Pavillon J.-Armand-Bombardier\, 5155\, 
 chemin de la rampe \, Montréal\, QC\, Canada\, H3T 2B2
SUMMARY:Frustration and low-dimensional physics in SrR2O4 – Amy Poole\, P
 SI\, Switzerland
DESCRIPTION:Amy Poole\, Laboratory for Neutron Scattering\, Paul Scherrer I
 nstitute\, Villigen\, SwitzerlandThis presentation will focus on frustrate
 d rare earth materials and\, in particular the Ho and Dy members of the re
 cently discovered SrR2O4 family of frustrated rare-earth (R) materials. Fr
 ustrated magnetic materials in general are systems in which the competi- t
 ion between interactions prevents the system from having a non-degenerate 
 ground state. This competition can either be due to a large number of rand
 om interactions\, such as those found in a spin glass or\, as found in geo
 metrically frustrated materials\, a few local equivalent interactions. Oft
 en these systems can be described by a simple model of the local interacti
 ons\, but can give rise to complexity and exotic quasi-particle excitation
 s in the bulk. Due to the frustrated arrangement of the R ions in SrR2O4 
 three-dimensional magnetic order is suppressed occurring only at TN = 0.66
  K in SrHo2O4 and is not observed to 50 mK in SrDy2O4. Our neutron powder
  diffraction measurements indicate that prior to the 3D order in the SrHo2
 O4 compound a 1D magnetically correlated state exists and that a similar 
 state is found at the lowest measured temperatures in SrDy2O4. The correla
 tion lengths of the 1D fluctuations have been extracted from neutron powde
 r scattering data and\, from fits to the 3D magnetic order found in the Ho
  analogue\, the local correlations can be understood to have an up-up-down
 -down arrangement (↑↑↓↓) as expected in the ground state of a J1-J
 2 spin chain model. The local Ising anisotropy was determined with an elec
 trostatic point charge model that was used to fit crystal field excitation
 s found with inelastic neutron scattering measurements. The combination of
  the strong local anisotropy and the low dimensional scattering strongly s
 uggest that these materials are realisations of the Ising J1-J2 spin chai
 n model at the classical limit. Site web du groupe du  Dr. PooleCette co
 nférence est présentée par le RQMP Versant Nord du Département de phy
 sique de l'Université de Montréal et le Département de génie physique 
 de Polytechnique Montréal.
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