Title: Thermally and field-driven mobility of emergent magnetic charges in square artificial spin ice

Abstract

Designing and constructing model systems that embody the statistical mechanics of frustration is now possible using nanotechnology. We have arranged nanomagnets on a two-dimensional square lattice to form an artificial spin ice, and studied its fractional excitations, emergent magnetic monopoles, and how they respond to a driving field using X-ray magnetic microscopy. We observe a regime in which the monopole drift velocity is linear in field above a critical field for the onset of motion. The temperature dependence of the critical field can be described by introducing an interaction term into the Bean-Livingston model of field-assisted barrier hopping. By analogy with electrical charge drift motion, we define and measure a monopole mobility that is larger both for higher temperatures and stronger interactions between nanomagnets. The mobility in this linear regime is described by a creep model of zero-dimensional charges moving within a network of quasi-one-dimensional objects.

Authors:

Morley, Sophie A. ^[1]; Porro, Jose Maria ^[2]; Hrabec, Aleš ^[3]; Rosamond, Mark C. ^[3]; Venero, Diego Alba ^[4]; Linfield, Edmund H.  ^[3];

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Burnell, Gavin  ^[3];

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Im, Mi-Young ^[5]; Fischer, Peter  ^[6];

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Langridge, Sean  ^[4];

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Marrows, Christopher H.  ^[3]

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• Search DOE PAGES for ORCID "0000-0003-4812-6393"
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+ Show Author Affiliations

1. Univ. of Leeds, Leeds (United Kingdom); Univ. of California, Santa Cruz, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
2. Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab., ISIS Neutron and Muon Source; BCMaterials, Basque Center for Materials, Applications and Nanostructures, Leioa (Spain); Ikerbasque, Basque Foundation for Science, Bilbao (Spain)
3. Univ. of Leeds, Leeds (United Kingdom)
4. Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab., ISIS Neutron and Muon Source
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Daegu Gyeongbuk Inst. of Science and Technology, Daegu (Korea)
6. Univ. of California, Santa Cruz, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

2019-11-05

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Research Foundation of Korea (NRF); Engineering and Physical Sciences Research Council (EPSRC)

OSTI Identifier:

1580413

Grant/Contract Number:  

[AC02-05CH11231; EP/L00285X/1; EP/L003090/1]

Resource Type:

Accepted Manuscript

Journal Name:

Scientific Reports

Additional Journal Information:

[ Journal Volume: 9; Journal Issue: 1]; Journal ID: ISSN 2045-2322

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS