Morley, SA, Alba Venero, D, Porro, JM et al. (6 more authors) (2017) Vogel-Fulcher-Tammann freezing of a thermally fluctuating artificial spin ice probed by x-ray photon correlation spectroscopy. Physical Review B, 95 (10). 104422. ISSN 2469-9950
Abstract
We report on the crossover from the thermal to the athermal regime of an artificial spin ice formed from a square array of magnetic islands whose lateral size, 30 nm × 70 nm, is small enough that they are dynamic at room temperature. We used resonant magnetic soft x-ray photon correlation spectroscopy as a method to observe the time-time correlations of the fluctuating magnetic configurations of spin ice during cooling, which are found to slow abruptly as a freezing temperature of T0=178±5 K is approached. This slowing is well described by a Vogel-Fulcher-Tammann law, implying that the frozen state is glassy, with the freezing temperature being commensurate with the strength of magnetostatic interaction energies in the array. The activation temperature, TA=40±10 K, is much less than that expected from a Stoner-Wohlfarth coherent rotation model. Zero-field-cooled/field-cooled magnetometry reveals a freeing up of fluctuations of states within islands above this temperature, caused by variation in the local anisotropy axes at the oxidised edges. This Vogel-Fulcher-Tammann behavior implies that the system enters a glassy state upon freezing, which is unexpected for a system with a well-defined ground state.
Metadata
Authors/Creators: |
|
||||
---|---|---|---|---|---|
Copyright, Publisher and Additional Information: | © 2017 American Physical Society. This is an author produced version of a paper published in Physical Review B. Uploaded in accordance with the publisher's self-archiving policy. | ||||
Keywords: | Condensed Matter & Materials Physics; Spin ice; X-ray techniques | ||||
Dates: |
|
||||
Institution: | The University of Leeds | ||||
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Condensed Matter (Leeds) | ||||
Funding Information: |
|
||||
Depositing User: | Symplectic Publications | ||||
Date Deposited: | 20 Nov 2018 15:28 | ||||
Last Modified: | 02 Mar 2020 17:23 | ||||
Status: | Published | ||||
Publisher: | American Physical Society | ||||
Identification Number: | https://doi.org/10.1103/PhysRevB.95.104422 | ||||
Related URLs: |