Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice

被引：248

作者：

Mengotti, Elena ^{[1
]}

Heyderman, Laura J. ^{[1
]}

Rodriguez, Arantxa Fraile ^{[1
]}

Nolting, Frithjof ^{[1
]}

Huegli, Remo V. ^{[2
]}

Braun, Hans-Benjamin ^{[2
]}

机构：

[1] Paul Scherrer Inst, CH-5232 Villigen, Switzerland

[2] Univ Coll Dublin, Sch Phys, Dublin 4, Ireland

来源：

NATURE PHYSICS | 2011年 / 7卷 / 01期

基金：

瑞士国家科学基金会; 爱尔兰科学基金会;

关键词：

DYNAMICS; ENTROPY; PHASE;

D O I：

10.1038/NPHYS1794

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Magnetic monopoles have been predicted to occur as emergent fractional quasiparticles inside pyrochlore spin ice, a frustrated magnetic insulator. Experimental signatures of such emergent monopoles accompanied by Dirac strings have been detected by means of neutron scattering in reciprocal space in pyrochlore spin ice at sub-Kelvin temperatures, but their real-space observation has remained elusive. Here we report on direct, real-space observations of emergent monopoles and their associated Dirac strings in two-dimensional (2D) artificial kagome spin ice at room temperature using synchrotron X-ray photoemission electron microscopy. Magnetization reversal proceeds through the nucleation and avalanche-type dissociation of monopole-antimonopole pairs along 1D Dirac strings. This is in sharp contrast to conventional domain growth in 2D systems, providing a striking example of dimensional reduction due to frustration. The observed hysteresis, monopole densities and 1D Dirac-string avalanches are quantitatively explained by Monte Carlo simulations.

引用

页码：68 / 74

页数：7

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