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Title: Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet

Abstract

Frustrated magnetic systems exhibit highly degenerate ground states and strong fluctuations, often leading to new physics. An intriguing example of current interest is the antiferromagnet on a diamond lattice, realized physically in the A-site spinel materials. This is a prototypical system in three dimensions where frustration arises from competing interactions rather than purely geometric constraints, and theory suggests the possibility of novel order at low temperature. Here we present a comprehensive single crystal neutron scattering study CoAl2O4, a highly frustrated A-site spinel. We observe strong diffuse scattering that peaks at wavevectors associated with Neel ordering. Below the temperature T*=6.5K, there is a dramatic change in elastic scattering lineshape accompanied by the emergence of well-defined spin-wave excitations. T* had previously been associated with the onset of glassy behavior. Our new results suggest instead that in fact T* signifies a first-order phase transition, but with true long-range order inhibited by the kinetic freezing of domain walls. This scenario might be expected to occur widely in frustrated systems containing first-order phase transitions and is a natural explanation for existing reports of anomalous glassy behavior in other materials.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
High Flux Isotope Reactor; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1029212
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences; Journal Volume: 108; Journal Issue: 38
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DIAMONDS; DIFFUSE SCATTERING; DIMENSIONS; ELASTIC SCATTERING; FLUCTUATIONS; FREEZING; GROUND STATES; KINETICS; MONOCRYSTALS; NEUTRONS; PHYSICS; SCATTERING; SPINELS; ANTIFERROMAGNETISM

Citation Formats

MacDougall, Gregory J, Gout, Delphine J, Zarestky, Jerel L, Ehlers, Georg, Podlesnyak, Andrey A, McGuire, Michael A, Mandrus, David, and Nagler, Stephen E. Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet. United States: N. p., 2011. Web. doi:10.1073/pnas.1107861108.
MacDougall, Gregory J, Gout, Delphine J, Zarestky, Jerel L, Ehlers, Georg, Podlesnyak, Andrey A, McGuire, Michael A, Mandrus, David, & Nagler, Stephen E. Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet. United States. doi:10.1073/pnas.1107861108.
MacDougall, Gregory J, Gout, Delphine J, Zarestky, Jerel L, Ehlers, Georg, Podlesnyak, Andrey A, McGuire, Michael A, Mandrus, David, and Nagler, Stephen E. Sat . "Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet". United States. doi:10.1073/pnas.1107861108.
@article{osti_1029212,
title = {Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet},
author = {MacDougall, Gregory J and Gout, Delphine J and Zarestky, Jerel L and Ehlers, Georg and Podlesnyak, Andrey A and McGuire, Michael A and Mandrus, David and Nagler, Stephen E},
abstractNote = {Frustrated magnetic systems exhibit highly degenerate ground states and strong fluctuations, often leading to new physics. An intriguing example of current interest is the antiferromagnet on a diamond lattice, realized physically in the A-site spinel materials. This is a prototypical system in three dimensions where frustration arises from competing interactions rather than purely geometric constraints, and theory suggests the possibility of novel order at low temperature. Here we present a comprehensive single crystal neutron scattering study CoAl2O4, a highly frustrated A-site spinel. We observe strong diffuse scattering that peaks at wavevectors associated with Neel ordering. Below the temperature T*=6.5K, there is a dramatic change in elastic scattering lineshape accompanied by the emergence of well-defined spin-wave excitations. T* had previously been associated with the onset of glassy behavior. Our new results suggest instead that in fact T* signifies a first-order phase transition, but with true long-range order inhibited by the kinetic freezing of domain walls. This scenario might be expected to occur widely in frustrated systems containing first-order phase transitions and is a natural explanation for existing reports of anomalous glassy behavior in other materials.},
doi = {10.1073/pnas.1107861108},
journal = {Proceedings of the National Academy of Sciences},
number = 38,
volume = 108,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2011},
month = {Sat Jan 01 00:00:00 EST 2011}
}