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Nonequilibrium hysteresis and spin relaxation in the mixed-anisotropy dipolar-coupled spin-glass LiHo0.5Er0.5F4

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2014
Author Piatek J. O., Kovacevic I., Babkevich P., Piazza B. Dalla, Neithardt S., Gavilano J., Kraemer K. W., Ronnow H. M.,
Project Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials
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Original article (peer-reviewed)

Journal PHYSICAL REVIEW B
Volume (Issue) 90(17)
Page(s) 174427
Title of proceedings PHYSICAL REVIEW B
DOI 10.1103/PhysRevB.90.174427

Open Access

URL http://infoscience.epfl.ch/record/204024?ln=en
Type of Open Access Repository (Green Open Access)

Abstract

We present a study of the model spin-glass LiHo0.5Er0.5F4 using simultaneous ac susceptibility, magnetization, and magnetocaloric effect measurements along with small angle neutron scattering ( SANS) at sub-Kelvin temperatures. All measured bulk quantities reveal hysteretic behavior when the field is applied along the crystallographic c axis. Furthermore, avalanchelike relaxation is observed in a static field after ramping from the zero-field-cooled state up to 200-300 Oe. SANS measurements are employed to track the microscopic spin reconfiguration throughout both the hysteresis loop and the related relaxation. Comparing the SANS data to inhomogeneous mean-field calculations performed on a box of one million unit cells provides a real-space picture of the spin configuration. We discover that the avalanche is being driven by released Zeeman energy, which heats the sample and creates positive feedback, continuing the avalanche. The combination of SANS and mean-field simulations reveal that the conventional distribution of cluster sizes is replaced by one with a depletion of intermediate cluster sizes for much of the hysteresis loop.
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