Janson O, Furukawa S, Momoi T, Sindzingre P, Richter J, Held K
Institut für Festkörperphysik, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.
Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Phys Rev Lett. 2016 Jul 15;117(3):037206. doi: 10.1103/PhysRevLett.117.037206. Epub 2016 Jul 12.
Motivated by recent experiments on volborthite single crystals showing a wide 1/3-magnetization plateau, we perform microscopic modeling by means of density functional theory (DFT) with the single-crystal structural data as a starting point. Using DFT+U, we find four leading magnetic exchanges: antiferromagnetic J and J_{2}, as well as ferromagnetic J^{'} and J_{1}. Simulations of the derived spin Hamiltonian show good agreement with the experimental low-field magnetic susceptibility and high-field magnetization data. The 1/3-plateau phase pertains to polarized magnetic trimers formed by strong J bonds. An effective J→∞ model shows a tendency towards condensation of magnon bound states preceding the plateau phase.
受近期关于硫钒铜矿单晶实验的启发，这些实验显示出宽1/3磁化平台，我们以单晶结构数据为起点，通过密度泛函理论（DFT）进行微观建模。使用DFT+U，我们发现了四个主要的磁交换：反铁磁J和J₂，以及铁磁J′和J₁。对导出的自旋哈密顿量的模拟与实验低场磁化率和高场磁化数据显示出良好的一致性。1/3平台相属于由强J键形成的极化磁三聚体。一个有效的J→∞模型显示在平台相之前存在磁振子束缚态凝聚的趋势。
