导入无序的低维有机磁性相变材料的磁相调控

Magnetic phase transition in low-dimensional organic magnetic systems have attracted considerable attentions for its intriguing emergent phenomena, like low-dimensional magnetic structure, spin fluctuation and magnetic frustration et.al. The origin of the magnetic phase transition and the transformation of the ground state, however, is still under debate. Among the various methods, disordered doping has been adopted to induce the magnetic phase transition. Very recently, the novel transformation from the gapped spin liquid ground state to the Mott glass state and the occurrence of the Bose glass state at the boundary of magnon Bose-Einstein condensates phase (BEC) induced in magnetic field have been observed in antiferromagnetic two-leg spin (S=1/2) ladders IPA-CuCl3 and one-dimensional spin (S=1) chain 4SC(NH2)2NiCl2 (DTN) with the nonmagnetic Br atoms dopping. In order to fully understand the dopping effect on the magnetic phase transition and Haldane deduction, the dopping using magnetic atoms with different spin properties have been proposed. In this project, we will synthesize four kinds of low-dimensional organic magnetic systems, i.e. the fully and partial replace of the Cu (S=1/2) with Ni (S=1) in IPA-CuCl3, and the fully and partial replace of the Ni (S=1) with Cu (S=1/2) in 4SC (NH2)2NiCl2, using the water solution method. By adopting of the X-ray diffraction and the low temperature and high magnetic measurement systems, the crystal structures, magnetic structures, magnetic phase transition and the ground states will be determined, and the disorder dopping effect on the magnetic structures, ground states and the magnetic phase transition also will be explored. This project will pave a new way for the better understand of the phase transition of the low-dimensional magnetic systems, and shed light on extending the experimental researches on the novel magnetic materials.

由于低维有机磁性材料中低维磁结构、自旋涨落、磁阻挫等特性，其相变起源与机理一直存在争议。而通过掺杂等方式的无序调控磁相方法是研究磁相材料的通用手段，其中非磁性掺杂Br对磁结构为两条腿自旋梯IPA-CuCl3和一维自旋链4SC(NH2)2NiCl2的磁相影响尤为瞩目：其基态由自旋液体变为莫特玻璃态，且在磁场诱导的玻色-爱因斯坦凝聚相两侧出现玻色玻璃相。但目前该相变的起源与机理均没有得到很好的解释。为此，本项目拟从霍尔顿推论入手，以互换或不同比例共存的方式将Cu(S=1/2)/Ni(S=1)等不同特性自旋的磁性粒子引入上述两材料，并通过水浴法制备晶体，X射线衍射确定结构，及磁学和热力学等物性表征，分析磁结构和磁相变，澄清不同自旋性质的磁性无序对这两种材料的磁结构、基态和磁相的影响。本项目可为深入理解低维有机磁性材料的相变规律提供实验依据，并为实验合成新型磁相材料提供参考。

本项目在极低温，强磁场和高压的极端条件下，通过掺杂等方式来研究有机材料的晶体结构和物理性质，从而来调控相转变。1、以将同比例共存的方式将磁性金属Cu和非磁性金属Zn引入一维自旋链4SC(NH2)2NiCl2材料，并通过水浴法制备晶体，X射线衍射确定结构，及磁学和热力学等物性表征，澄清磁性金属对相变材料的晶体结构和相转变的影响。2、在高压的极端条件下，研究有机材料的结构相变和物理性质。本项目可为深入理解有机材料的相变规律提供实验依据，并为实验合成新型相变材料提供参考。