Mid-Atlantic Section Meeting 2021
Volume 66, Number 18
Friday–Sunday, December 3–5, 2021;
Rutgers University, New Brunswick, New Jersey
Session B01: Quantum Matter: Magnetism
5:00 PM–7:00 PM,
Friday, December 3, 2021
Room: 201A
Chair: Sang Wook Cheong, Rutgers University
Abstract: B01.00003 : Magneto-Raman studies of magnons in 2D magnetic materials and quantum magnet CoTiO3
5:48 PM–6:24 PM
Preview Abstract
Abstract
Author:
Thuc Mai
(National Institute of Standards and Technology)
Raman spectroscopy is a versatile technique due to its non-destructive
nature, surface sensitivity, and low energy sensitivity, down to a few meV.
These attributes naturally lead to the use of Raman scattering as a probe of
quantized spin waves, or magnons, in magnetic materials. Our custom-built
magneto-Raman system comprises of a triple grating spectrometer, a magneto
cryostat with optical access, and multiple continuous wave laser lines that
cover the entire visible spectrum.
We first explore the magnetic excitations in two-dimensional (2D) magnetic
materials. Magnetic excitations in van der Waals (vdW) materials, especially
in the 2D limit, are an exciting research topic from both the fundamental
and applied perspectives. From the antiferromagnetic magnon gap excitation
in FePS3[1] to the hybridization of a two-magnon excitation with the phonons
in MnPSe3[2], our magneto-Raman studies revealed a rich set of magnetic
excitations in the family of vdW magnet MPX3, where M is a transition metal,
P is phosphorous, and X is Sulfur or Selenium. Second, we look at our
unpublished results on an exciting quantum material, CoTiO3. We follow the
evolution of the Brillouin Zone center excitations of not only the optical
magnon, but also several spin-orbit excitations across the magnetic
transition temperature. Our experiment provides a high-resolution
measurement of these magnetic modes at k$=$0. Additionally, by applying the
external magnetic field along the c-axis and along a hexagonal axis, we
reveal the highly anisotropic g-factor of these magnetic excitations.
Surprisingly, we measure the beginning of a magnetically induced crossing
between the acoustic and optical magnon. Our results are supported by
density functional theory (DFT) and linear spin wave theory (LSWT), as well
as being consistent with inelastic neutron scattering experiments in the
literature.
[1] McCreary et al. Phys. Rev. B 101, 064416 (2019)
[2] Mai et al. SCIENCE ADVANCES. 29 Oct 2021. Vol 7, Issue 44