Suppression of geometric frustration by magnetoelastic coupling in AuCrS2
Suppression of geometric frustration by magnetoelastic coupling in AuCrS2
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DOI：
10.1103/physrevb.84.094455
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发表时间：
2011-09-28
影响因子：
3.7
通讯作者：
Gauzzi, A.
中科院分区：
文献类型：
--
作者：
Carlsson, S. J. E.;Rousse, G.;Gauzzi, A.
我们研究了结构，磁性和电子性质的几何挫折分层AuCrS 2系统通过X射线和中子粉末衍射，比热，直流磁化，直流电阻率测量。室温结构细化与六边形中心对称R-3 m对称性以及形式价态Au+和Cr 3+一致，其中Cr 3+离子在六边形平面内形成规则的三角形晶格。在冷却过程中，我们观察到一个一级结构相变的单斜C2/m对称伴随着反铁磁秩序在T-N = 47 K。与这种转变相关的原子位移拉伸了三角晶格，从而抑制了几何挫折。这说明了所观察到的磁序，并给出了一个大的磁弹性耦合的证据。细化的磁结构是相称的，并由双铁磁链沿着的拉伸方向与μ = 2.54 μ B/Cr 3 +;剩余的挫折稳定一个优雅的图案交替的铁磁和反铁磁相邻链之间的平面内和平面间的耦合。我们的烧结粉末样品的电输运被发现是类似于157 Ω cm和0.38 eV的激活能的rho（300 K）的双稳态。
We studied the structural, magnetic, and electronic properties of the geometrically frustrated layered AuCrS2 system by means of x-ray and neutron powder diffraction, specific heat, dc magnetization, and dc electrical resistivity measurements. The room-temperature structural refinement is consistent with a hexagonal centrosymmetric R-3m symmetry and with formal valence states Au+ and Cr3+, where the Cr3+ ions form a regular triangular lattice within the hexagonal planes. On cooling, we observe a first-order structural phase transition to a monoclinic C2/m symmetry concomitant to an antiferromagnetic order at T-N = 47 K. The atomic displacements associated with this transition stretch the triangular lattice, thus suppressing the geometric frustration. This accounts for the magnetic order observed and gives evidence of a large magnetoelastic coupling. The refined magnetic structure is commensurate and consists of double ferromagnetic chains along the stretching direction with mu = 2.54 mu B/Cr3+; the residual frustration stabilizes an elegant pattern of alternate ferromagnetic and antiferromagnetic intra-and interplane couplings between adjacent chains. The electrical transport of our sintered powder samples is found to be semiconducting-like with rho(300K) similar to 157 Omega cm and an activation energy of 0.38 eV.