Colloquia

Recent developments in two-dimensional (2D) magnetism have intensified the research on novel van-der Waals magnetic materials to explore new magnetic phenomena in the 2D limit. Among 2D magnetic materials, one model system is metal thiophosphates MPX3 (M = transition metal ions, X = chalcogen ions) in which the antiferromagnetic (AFM) properties are highly dependent on the choice of transition metal M. The van der Waals-type crystal structure allows the mechanical exfoliation of bulk crystals to obtain atomically thin layers. In MPX3, the AFM ordering is found to persist down to the atomically thin limit, making them a promising candidate for future device applications. Furthermore, the layered structure also permits the inter-layer intercalation, which is an effective way to tune the properties. With this motivation, we performed Li and Fe intercalation in NiPS3 by using electrochemical technique. In this method, the electrical potential causes electrons to flow from anode to cathode through the circuit within the battery leading to the intercalation of intercalant ions between the layers of the host sample as shown in figure below. By tuning the amount of charges intercalated during electrochemical intercalation, the number of intercalated ions in the host single crystal can be controlled. NiPS3 exhibits AFM ordering below TN = 155 K and the spin-flop transition above μ0H ≈ 6 T. The goal of this project is to intercalate different Li and Fe content in NiPS3 single crystals and characterize their magnetic properties. Mainly, we will focus on the tuning of the ordering temperature and the spin-flop field of pristine NiPS3. In addition, the transition from AFM state to other states such as ferromagnetism is also one important direction of this project. Li intercalation was found to increase the magnetization value of NiPS3.  Future work will consist of characterizing the changes in the magnetic ordering of Fe intercalated NiPS3 and extending the investigation of Li intercalated NiPS3.