Hexagonal boron nitride research in the Henriksen Lab

Yiwei Le and Jeree Murray
Washington University, St. Louis, Missouri, USA _______________________________________

We often employ hexagonal boron nitride in crafting ‘van der Waals heterostructure’ devices for exploring physics of graphene or other 2D materials. Here we describe two new projects that start with or rely on the physics of hBN. 

First, in collaboration with the lab of Chong Zu (WashU), we aim to utilize the sensitivity of boron vacancy defects in hBN to probe ‘interesting’ magnetic materials. For instance, we wish to measure the magnetic field fluctuations in the neighborhood of a-RuCl3—a candidate Kitaev quantum spin liquid material—to explore the role of Kitaev-type magnetism in layered materials. To calibrate our optical setup, we have performed ODMR spectra measurements on bulk diamonds with implanted defects and seek to subsequently perform measurements on 2D quasi diamond crystals, and eventually hBN.

Recently, we have developed a version of 3? thermal measurements suitable for 2D materials. We measure the thermal impedance of a suspended flake of a given layered material using a single wire patterned on the flake that is used to both heat the sample and measure the thermal response. In principle we can access both the thermal conductivity and specific heat by fitting the thermal impedance to a one-dimensional model of heat flow. In the case of hBN, we extract the thermal conductivity, demonstrating the feasibility of applying the 3? method to study 2D materials.

Email: le.y@wustl.edu, jeree@wustl.edu