Magnetic ground state of a highly two-dimensional spin-1/2 antiferromagnet

The physics of low-dimensional magnets is starkly different to that of more traditional isotropic materials. Novel phase transitions and exotic phenomena are expected in highly 1D and 2D magnets. The theory of such systems was the subject of the 2016 Nobel Prize in Physics. However, creating real low-dimensional materials in which these theories can be tested has proven to be difficult. Progress in this area has been made in recent years by looking at materials in which the magnetic ions are held apart by molecular bridges. We have recently characterised one of the most 2D spin-1/2 antiferromagnets yet discovered. We propose to determine the magnetic ground state of this system, a challenging prospect due to the low-spin density and small ordered moment expected in very 2D magnets. However, if this experiment is possible anywhere, it is at the WISH instrument at ISIS.

低维磁体的物理性质与传统各向同性材料截然不同。在高度一维(1D)和二维(2D)磁体中，有望观测到全新的相变与新奇物理现象。这类体系的相关理论研究曾是2016年诺贝尔物理学奖的获奖课题。然而，制备出可用于验证这些理论的真实低维材料，却始终是一项难题。近年来，通过研究利用分子桥分隔磁离子的材料体系，该领域已取得一定进展。我们近期已对目前已发现的最具二维特性的自旋-1/2反铁磁体之一完成了表征。我们计划测定该体系的磁基态，但这是一项极具挑战性的工作——这是因为在极致二维磁体中，自旋密度较低且有序磁矩微弱。然而，若全球范围内有任何一处可开展此类实验，那必然是ISIS的WISH谱仪。