Yamaguchi Hironori, Okubo Tsuyoshi, Kittaka Shunichiro, Sakakibara Toshiro, Araki Koji, Iwase Kenji, Amaya Naoki, Ono Toshio, Hosokoshi Yuko
Department of Physical Science, Osaka Prefecture University, Osaka 599-8531, Japan.
Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581, Japan.
Sci Rep. 2015 Oct 15;5:15327. doi: 10.1038/srep15327.
Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL.
几何阻挫，即相互竞争的相互作用导致简并基态，有可能在磁性材料中引发各种奇异的量子现象。为了实现诸如量子自旋液体等新型量子相，包含三角形单元（如三角形和 Kagome 晶格）的最小模型已被研究了数十年。五边形是产生几何阻挫的第二小基本单元。此类系统的实现有望为研究阻挫磁性提供一个独特的平台。在此，我们展示了一种新型有机自由基晶体α-2,6-Cl2-V [=α-3-(2,6-二氯苯基)-1,5-二苯基联氮自由基] 中的自旋-1/2 量子五边形晶格。其独特的分子排列允许形成部分角共享五边形晶格（PCPL）。我们发现了一个清晰的 1/3 磁化平台以及在饱和场附近磁化强度的异常变化，这源于 PCPL 中的阻挫相互作用。
