Two-dimensional (2D) van der Waals (vdWs) materials have gathered a lot of attention recently. However, the majority of these materials have Curie temperatures that are well below room temperature, making it challenging to incorporate them into device applications. In this work, we synthesized a room-temperature vdW magnetic crystal Fe5GeTe2 with a Curie temperature Tc=332 K, and studied its magnetic properties by vibrating sample magnetometry (VSM) and broadband ferromagnetic resonance (FMR) spectroscopy. The experiments were performed with external magnetic fields applied along the c-axis (H∥c) and the ab-plane (H∥ab), with temperatures ranging from 300 K to 10 K. We have found a sizable Land\'e g-factor difference between the H∥c and H∥ab cases. In both cases, the Land\'e g-factor values deviated from g = 2. This indicates contribution of orbital angular momentum to the magnetic moment. The FMR measurements reveal that Fe5GeTe2 has a damping constant comparable to Permalloy. With reducing temperature, the linewidth was broadened. Together with the VSM data, our measurements indicate that Fe5GeTe2 transitions from ferromagnetic to ferrimagnetic at lower temperatures. Our experiments highlight key information regarding the magnetic state and spin scattering processes in Fe5GeTe2, which promote the understanding of magnetism in Fe5GeTe2, leading to implementations of Fe5GeTe2 based room-temperature spintronic devices.
@article{arxiv.2103.13433,
title = {Magnetism and Spin Dynamics in Room-Temperature van der Waals Magnet Fe$_5$GeTe$_2$},
author = {Laith Alahmed and Bhuwan Nepal and Juan Macy and Wenkai Zheng and Arjun Sapkota and Nicholas Jones and Alessandro R. Mazza and Matthew Brahlek and Wencan Jin and Masoud Mahjouri-Samani and Steven S. L. Zhang and Claudia Mewes and Luis Balicas and Tim Mewes and Peng Li},
journal= {arXiv preprint arXiv:2103.13433},
year = {2021}
}