Investigation of the magnetic ground state of a halide perovskite heterostructure.

The halide perovskite heterostructure (CuCl4)2(MTPA)4Cu3Cl6 (Cu_Cu; MTPA = 3-(methylthio)-propylammonium) forms from solution as single crystals consisting of alternating layers of 2D CuII-Cl perovskite and 1D CuII-Cl diamond–chain intergrowth. Using magnetometry, heat capacity, and electron paramagnetic resonance measurements, we have interrogated the magnetic ordering of the 2D perovskite layer and the 1D intergrowth layer at temperatures down to 55 mK. No long–range magnetic ordering event in the intergrowth is evident, suggesting that, due to the geometric constraints imposed by the perovskite framework, individual diamond chains in the intergrowth of Cu_Cu are magnetically isolated from one another. In contrast, comparable motifs in well–studied diamond spin chain materials such as azurite do not show magnetic 1D character at low temperatures due to interchain contacts in the solid state. As such, Cu_Cu provides an ideal platform for studying isolated, anisotropic spin chains. This material illustrates the capability of halide perovskite heterostructures to serve as vehicles for the scalable synthesis of complex multi–layered magnetic materials. A heat capacity anomaly at 0.3 K suggests some local spin pairing in Cu_Cu. We aim to use muon spin relaxation measurements above and below this temperature to conclusively demonstrate a lack of long-range magnetic ordering, which would be consistent with our proposal of a 1D Heisenberg spin chain ground state in the intergrowth.

卤化物钙钛矿异质结构(CuCl4)2(MTPA)4Cu3Cl6（记为Cu_Cu；MTPA = 3-(甲硫基)丙铵，3-(methylthio)-propylammonium）可从溶液中生长得到由二维Cu(II)-Cl钙钛矿与一维Cu(II)-Cl金刚石链共生结构交替堆叠而成的单晶。我们借助磁测量、热容测试与电子顺磁共振表征，在低至55毫开的温度区间内探究了该材料中二维钙钛矿层与一维共生层的磁有序行为。一维共生层未表现出长程磁有序现象，这表明受钙钛矿骨架施加的几何约束影响，Cu_Cu共生结构中的单个金刚石链彼此之间处于磁隔离状态。与之形成鲜明对比的是，在研究较为充分的金刚石自旋链材料（如蓝铜矿）中，由于固态下存在链间相互作用，其低温下并未表现出一维磁学特性。因此，Cu_Cu是研究孤立各向异性自旋链的理想平台。该材料证实了卤化物钙钛矿异质结构可作为可规模化合成复杂多层磁性材料的有效载体。其在0.3 K处出现的热容反常现象，暗示Cu_Cu中存在一定程度的局域自旋配对。我们计划通过在该温度上下开展μ子自旋弛豫测试，确凿证明其无长程磁有序行为，这将与我们提出的一维海森堡自旋链基态假说相符。