Lefrançois E, Cathelin V, Lhotel E, Robert J, Lejay P, Colin C V, Canals B, Damay F, Ollivier J, Fåk B, Chapon L C, Ballou R, Simonet V
Institut Laue Langevin, CS 20156, 38042, Grenoble, France.
Institut Néel, CNRS and Univ. Grenoble Alpes, 38042, Grenoble, France.
Nat Commun. 2017 Aug 8;8(1):209. doi: 10.1038/s41467-017-00277-1.
The complexity embedded in condensed matter fertilizes the discovery of new states of matter, enriched by ingredients like frustration. Illustrating examples in magnetic systems are Kitaev spin liquids, skyrmions phases, or spin ices. These unconventional ground states support exotic excitations, for example the magnetic charges in spin ices, also called monopoles. Here, we propose a mechanism to inject monopoles in a spin ice at equilibrium through a staggered magnetic field. We show theoretically, and demonstrate experimentally in the HoIrO pyrochlore iridate, that it results in the stabilization of a monopole crystal, which exhibits magnetic fragmentation. In this new state of matter, the magnetic moment fragments into an ordered part and a persistently fluctuating one. Compared to conventional spin ices, the different nature of the excitations in this fragmented state opens the way to tunable field-induced and dynamical behaviors.Exploring unconventional magnetism facilities both fundamental understanding of materials and their real applications. Here the authors demonstrate that a magnetic monopole crystal is stabilized by a staggered magnetic field in the pyrochlore iridate HoIrO, leading to a fragmented magnetization.
凝聚态物质中所蕴含的复杂性孕育了新物态的发现，而诸如阻挫等因素使其更加丰富。磁系统中的典型例子有基泰耶夫自旋液体、斯格明子相或自旋冰。这些非常规基态支持奇特的激发态，例如自旋冰中的磁荷，也被称为磁单极子。在此，我们提出一种机制，通过交错磁场在平衡态的自旋冰中注入磁单极子。我们通过理论证明，并在钬铱氧化物烧绿石中进行了实验验证，这会导致磁单极子晶体的稳定化，该晶体呈现出磁破碎现象。在这种新的物态中，磁矩分裂为一个有序部分和一个持续波动的部分。与传统自旋冰相比，这种破碎态激发态的不同性质为可调谐的场致和动力学行为开辟了道路。探索非常规磁性有助于对材料的基本理解及其实际应用。在此，作者证明了在钬铱氧化物烧绿石中，交错磁场使磁单极子晶体稳定，从而导致磁化破碎。
