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Title: Thermodynamics of emergent magnetic charge screening in artificial spin ice

Abstract

Electric charge screening is a fundamental principle governing the behaviour in a variety of systems in nature. Through reconfiguration of the local environment, the Coulomb attraction between electric charges is decreased, leading, for example, to the creation of polaron states in solids or hydration shells around proteins in water. Here, we directly visualize the real-time creation and decay of screened magnetic charge configurations in a two-dimensional artificial spin ice system, the dipolar dice lattice. By comparing the temperature dependent occurrence of screened and unscreened emergent magnetic charge defects, we determine that screened magnetic charges are indeed a result of local energy reduction and appear as a transient minimum energy state before the system relaxes towards the predicted ground state. These results highlight the important role of emergent magnetic charges in artificial spin ice, giving rise to screened charge excitations and the emergence of exotic low-temperature configurations.

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [5];  [6]; ORCiD logo [7];  [8];  [3];  [9]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Aalto Univ., Otaniemi (Finland). School of Science
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  3. Aalto Univ., Otaniemi (Finland)
  4. Universita di Genova, Genova (Italy)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Daegu Gyeongbuk Institute of Science and Technology (DGIST)., Daegu (Korea, Republic of)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States), Molecular Foundry
  7. Univ. of California, Davis, CA (United States). Dept. of Materials Science and Engineering
  8. Adolfo Ibanez Univ., Santiago (Chile)
  9. Aalto Univ., Otaniemi (Finland). School of Science
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1377456
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ferromagnetism; magnetic properties and materials; metamaterials

Citation Formats

Farhan, Alan, Scholl, Andreas, Petersen, Charlotte F., Anghinolfi, Luca, Wuth, Clemens, Dhuey, Scott, Chopdekar, Rajesh V., Mellado, Paula, Alava, Mikko J., and van Dijken, Sebastiaan. Thermodynamics of emergent magnetic charge screening in artificial spin ice. United States: N. p., 2016. Web. doi:10.1038/ncomms12635.
Farhan, Alan, Scholl, Andreas, Petersen, Charlotte F., Anghinolfi, Luca, Wuth, Clemens, Dhuey, Scott, Chopdekar, Rajesh V., Mellado, Paula, Alava, Mikko J., & van Dijken, Sebastiaan. Thermodynamics of emergent magnetic charge screening in artificial spin ice. United States. doi:10.1038/ncomms12635.
Farhan, Alan, Scholl, Andreas, Petersen, Charlotte F., Anghinolfi, Luca, Wuth, Clemens, Dhuey, Scott, Chopdekar, Rajesh V., Mellado, Paula, Alava, Mikko J., and van Dijken, Sebastiaan. Thu . "Thermodynamics of emergent magnetic charge screening in artificial spin ice". United States. doi:10.1038/ncomms12635. https://www.osti.gov/servlets/purl/1377456.
@article{osti_1377456,
title = {Thermodynamics of emergent magnetic charge screening in artificial spin ice},
author = {Farhan, Alan and Scholl, Andreas and Petersen, Charlotte F. and Anghinolfi, Luca and Wuth, Clemens and Dhuey, Scott and Chopdekar, Rajesh V. and Mellado, Paula and Alava, Mikko J. and van Dijken, Sebastiaan},
abstractNote = {Electric charge screening is a fundamental principle governing the behaviour in a variety of systems in nature. Through reconfiguration of the local environment, the Coulomb attraction between electric charges is decreased, leading, for example, to the creation of polaron states in solids or hydration shells around proteins in water. Here, we directly visualize the real-time creation and decay of screened magnetic charge configurations in a two-dimensional artificial spin ice system, the dipolar dice lattice. By comparing the temperature dependent occurrence of screened and unscreened emergent magnetic charge defects, we determine that screened magnetic charges are indeed a result of local energy reduction and appear as a transient minimum energy state before the system relaxes towards the predicted ground state. These results highlight the important role of emergent magnetic charges in artificial spin ice, giving rise to screened charge excitations and the emergence of exotic low-temperature configurations.},
doi = {10.1038/ncomms12635},
journal = {Nature Communications},
number = ,
volume = 7,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2016},
month = {Thu Sep 01 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 7works
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  • Cited by 29
  • Reducing the dimensionality of a physical system can have a profound effect on its properties, as in the ordering of low-dimensional magnetic materials, phonon dispersion in mercury chain salts, sliding phases, and the electronic states of graphene. Here we explore the emergence of quasi-one-dimensional behaviour in two-dimensional artificial spin ice, a class of lithographically fabricated nanomagnet arrays used to study geometrical frustration. We extend the implementation of artificial spin ice by fabricating a new array geometry, the so-called tetris lattice. We demonstrate that the ground state of the tetris lattice consists of alternating ordered and disordered bands of nanomagnetic moments.more » The disordered bands can be mapped onto an emergent thermal one-dimensional Ising model. Furthermore, we show that the level of degeneracy associated with these bands dictates the susceptibility of island moments to thermally induced reversals, thus establishing that vertex frustration can reduce the relevant dimensionality of physical behaviour in a magnetic system.« less
  • Reducing the dimensionality of a physical system can have a profound effect on its properties, as in the ordering of low-dimensional magnetic materials, phonon dispersion in mercury chain salts, sliding phases, and the electronic states of graphene. Here we explore the emergence of quasi-one-dimensional behaviour in two-dimensional artificial spin ice, a class of lithographically fabricated nanomagnet arrays used to study geometrical frustration. We extend the implementation of artificial spin ice by fabricating a new array geometry, the so-called tetris lattice. We demonstrate that the ground state of the tetris lattice consists of alternating ordered and disordered bands of nanomagnetic moments.more » The disordered bands can be mapped onto an emergent thermal one-dimensional Ising model. Furthermore, we show that the level of degeneracy associated with these bands dictates the susceptibility of island moments to thermally induced reversals, thus establishing that vertex frustration can reduce the relevant dimensionality of physical behaviour in a magnetic system.« less
  • Magnetic reversal of an artificial square ice pattern subject to a sequence of magnetic fields applied slightly off the diagonal axis is investigated via magnetic force microscopy of the remanent states that result. Sublattice independent reversal is observed via correlated incrementally pinned flip cascades along parallel dipolar chains, as evident from analysis of vertex populations and dipolar correlation functions. Weak dipolar interactions between adjacent chains favour antialignment and give rise to weak charge ordering of 'monopole' vertices during the reversal process.