Vivek Dwij
Spintronic devices utilize electron spins for information processing and are promising candidates for ultra-low-power technologies that extend beyond CMOS electronics [1]. Their ultimate speed, switching efficiency, and energy dissipation are governed by the exchange of energy and angular momentum among electronic, magnonic, and phononic subsystems [2]. Among these interactions, spin–phonon coupling is particularly critical because it mediates energy flow between spin and lattice reservoirs, dynamically modifying magnetic anisotropy and thereby influencing both static magnetic order and its response to ultrafast perturbations [3].
Antiferromagnetic materials provide an ideal platform to investigate these processes. Their strong coupling between crystal structure and spin configuration, combined with intrinsic terahertz spin dynamics, makes them attractive for high-speed spintronic applications. In such systems, lattice vibrations are highly sensitive to spin ordering, meaning that changes in magnetic symmetry and exchange interactions directly renormalize phonon energies, lifetimes, and selection rules. Vibrational spectroscopy is therefore uniquely suited to probe spin–phonon coupling: it provides symmetry-resolved, mode-specific access to lattice dynamics with sufficient sensitivity to detect subtle spin-driven modifications that are difficult to isolate with other techniques.
In this talk, I will present vibrational spectroscopy studies that establish quantitative relationships between phonon renormalization and magnetic ordering in antiferromagnets. Two case studies illustrate these principles. In CuO, a prototypical high-TC multiferroic antiferromagnet, we identify the specific directional atomic displacements that mediate spin-induced ferroelectric polarization, thereby linking magnetic exchange interactions to lattice symmetry breaking [4]. In CrVO₄, where competing magnetic exchange pathways generate strong spin frustration, we observe exceptionally robust spin–orbital–phonon coupling that leads to giant phonon renormalization, highlighting the pronounced sensitivity of lattice modes to magnetic and electronic correlations [5]. Although these measurements probe equilibrium states, they reveal the microscopic coupling constants and symmetry constraints that govern energy flow on ultrafast timescales. Such equilibrium benchmarks are essential for predicting and ultimately controlling magnetic switching pathways under femtosecond excitation.
References:
[1] J. A. C. Incorvia et al Nat Rev Electr Eng 1, 700–713 (2024).
[2] Evgeny A. Mashkovich, et al., Science 374.6575 (2021): 1608-1611.
[3] A. Kimel et al. Nature 435, 655–657 (2005).
[4] B. K. De et al, Journal of Physics: Condensed Matter, 33(12), 12LT01 (2021).
[5] A. P. Roy et al., Physical Review Letters, 132(2), 026701 (2024).