在渗流时的 Bethe 格子中的突发自旋激发。

Emergent spin excitations in a Bethe lattice at percolation.

机构信息

Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.

出版信息

Phys Rev Lett. 2013 Oct 11;111(15):157201. doi: 10.1103/PhysRevLett.111.157201. Epub 2013 Oct 7.

DOI:10.1103/PhysRevLett.111.157201

Abstract

We study the spin-1/2 quantum Heisenberg antiferromagnet on a Bethe lattice diluted to the percolation threshold. Dilution creates areas of even or odd sublattice imbalance resulting in "dangling spins" [L. Wang and A. W. Sandvik, Phys. Rev. Lett. 97, 117204 (2006); Phys. Rev. B 81, 054417 (2010)]. These collectively act as "emergent" spin-1/2 degrees of freedom and are responsible for the creation of a set of low-lying "quasidegenerate states." Using density matrix renormalization group calculations, we detect the presence and location of these emergent spins. We find an effective Hamiltonian of these emergent spins, with Heisenberg interactions that decay exponentially with the distance between them.

摘要

我们研究了在达到渗流阈值时被稀释的 Bethe 格子上的自旋-1/2 量子海森堡反铁磁体。稀释会产生偶数或奇数子晶格失衡的区域，从而导致“悬置自旋”[L. Wang 和 A. W. Sandvik，Phys. Rev. Lett. 97, 117204 (2006); Phys. Rev. B 81, 054417 (2010)]。这些自旋集体表现为“涌现”的自旋-1/2 自由度，并负责产生一组低能的“拟简并态”。我们使用密度矩阵重整化群计算，检测到了这些涌现自旋的存在和位置。我们发现了这些涌现自旋的有效哈密顿量，其中海森堡相互作用随它们之间的距离呈指数衰减。