蓝铜矿中自旋动力学的本质及 1/3 磁化平台

Nature of the spin dynamics and 1/3 magnetization plateau in azurite.

作者信息

Rule K C, Wolter A U B, Süllow S, Tennant D A, Brühl A, Köhler S, Wolf B, Lang M, Schreuer J

机构信息

Hahn-Meitner-Institut GmbH, D-14109 Berlin, Germany.

出版信息

Phys Rev Lett. 2008 Mar 21;100(11):117202. doi: 10.1103/PhysRevLett.100.117202. Epub 2008 Mar 19.

DOI:10.1103/PhysRevLett.100.117202

PMID:18517818

Abstract

We present a specific heat and inelastic neutron scattering study in magnetic fields up into the 1/3 magnetization plateau phase of the diamond chain compound azurite Cu3(CO3)2(OH)2. We establish that the magnetization plateau is a dimer-monomer state, i.e., consisting of a chain of S=1/2 monomers, which are separated by S=0 dimers on the diamond chain backbone. The effective spin couplings Jmono/kB=10.1(2) K and Jdimer/kB=1.8(1) K are derived from the monomer and dimer dispersions. They are associated to microscopic couplings J1/kB=1(2) K, J2/kB=55(5) K and a ferromagnetic J3/kB=-20(5) K, possibly as result of dz2} orbitals in the Cu-O bonds providing superexchange (SE) pathways with JSE=6.5 K.

摘要

我们展示了在磁场中对蓝铜矿Cu3(CO3)2(OH)2金刚石链化合物直至1/3磁化平台相的比热和非弹性中子散射研究。我们确定磁化平台是一种二聚体 - 单体状态，即由S = 1/2单体链组成，这些单体在金刚石链主链上被S = 0二聚体隔开。有效自旋耦合Jmono/kB = 10.1(2) K和Jdimer/kB = 1.8(1) K是从单体和二聚体色散中推导出来的。它们与微观耦合J1/kB = 1(2) K、J2/kB = 55(5) K以及铁磁J3/kB = -20(5) K相关，这可能是由于Cu - O键中的dz2轨道提供了具有JSE = 6.5 K的超交换（SE）途径的结果。