Magnon-Induced Electric Polarization and the Hidden Nernst Phenomena in Quantum Magnonics

Magnons which is collective excitations of spin in magnetic systems have emerged as promising candidates for low-dissipation information transport. Unlike electrons, magnons carry angular momentum without electric charge, which allows spin information to propagate without Joule heating. This property positions magnonics at the forefront of future spintronic and orbitronic devices. Yet, one major obstacle persists: the efficient excitation, manipulation, and detection of magnons. Conventional spin-based effects, such as the magnon Seebeck and spin Nernst phenomena, rely on temperature gradients and are thus difficult to control locally or modulate rapidly. To overcome this limitation, researchers have begun to explore the coupling between magnonic spin, orbital angular momentum (OAM), and electric polarization—an emerging field linking spintronics and orbitronics into a unified framework. New research paper published in Proceedings of the National Academy of Sciences  and conducted by Dr. D. Quang To, Dr. Federico Garcia-Gaitan, Dr. Yafei Ren, Dr.  Joshua M.  Zide, Dr.  Benjamin Jungfleisch, Dr.  John Xiao, Professor Branislav Nikolić, Professor Garnett Bryant, and led by Professor Matthew Doty from the University of Delaware, the authors developed two complementary quantum-mechanical models describing magnon-induced electric polarization: one capturing equilibrium effects from intrinsic magnon spin and orbital moments, and another addressing non-equilibrium transport under thermal gradients. These models unify spin and orbital Nernst effects within a single theoretical framework, establishing a direct connection between magnon angular momentum and measurable electric fields. By applying this theory to honeycomb and Kagomé antiferromagnets, they identified symmetry and hybridization as tunable levers for enhancing polarization magnitude.To reveal the interplay between magnon transport and electric polarization, the researchers established a quantum-mechanical formalism linking magnon spin and orbital moments to induced polarization currents. Their theoretical framework extends the Kubo linear-response model to include Berry curvature terms associated with both spin and orbital angular momentum, thereby unifying the spin Nernst and orbital Nernst effects into a single description. Within this approach, magnons excited by a longitudinal temperature gradient (∇T) are deflected transversely, accumulating angular momentum at the system edges. These edge accumulations create local electric dipoles of opposite orientations, generating measurable voltages when symmetry between them is broken—most notably through the Dzyaloshinskii–Moriya interaction.

The research team first examined two-dimensional honeycomb antiferromagnets: MnPS₃ with Néel order and NiPSe₃ with Zigzag order. Using a bosonic Bogoliubov–de Gennes Hamiltonian derived via the Holstein–Primakoff transformation, the authors calculated the electric polarization from both magnon spin Berry curvature and intraband OAM contributions. In the absence of DMI, both systems preserved mirror symmetry, yielding zero net polarization despite finite local effects. Once DMI was introduced, symmetry breaking allowed magnons with opposite chirality to populate unevenly at opposite edges, resulting in a finite transverse voltage. Quantitatively, NiPSe₃ exhibited a net electric polarization about three orders of magnitude greater than MnPS₃. The difference arose because the Zigzag-ordered NiPSe₃ supports even-parity orbital moments and stronger magnon band hybridization, amplifying its orbital contribution (Pᴼᵧ) relative to the spin component (Pˢᵧ). The framework was then extended to a noncollinear Kagomé lattice antiferromagnet, KFe₃(OH)₆(SO₄)₂, which possesses a 120° spin structure stabilized by competing exchange and DMI interactions. Here, the researchers demonstrated that external magnetic fields could tune magnon hybridization, enabling active control over induced polarization. The hybridized magnon bands exhibited enhanced Berry curvature and orbital moment densities, producing electric polarization and transverse voltages up to five orders of magnitude greater than in MnPS₃. This tunability suggests a practical strategy for amplifying magnonic responses through symmetry engineering or field modulation.

In conclusion, the implications of this work extend beyond fundamental magnetism into the broader landscape of low-power electronics and quantum information science. By establishing that magnon transport inherently carries both spin and orbital angular momentum capable of inducing electric polarization, the researchers have effectively introduced a mechanism for purely electrical control and readout of magnonic states. This bridges the gap between spintronics, which relies on spin currents, and orbitronics, which manipulates orbital degrees of freedom. The resulting concept of “magnon-induced polarization” transforms the way magnetic excitations are understood—not as passive spin waves but as active entities that intertwine magnetic and electric responses. From a materials perspective, the framework identifies key symmetry conditions that determine whether electric polarization can emerge. In collinear systems such as MnPS₃, inversion and mirror symmetries restrict polarization unless broken by DMI or magnon–phonon coupling. In contrast, noncollinear or Zigzag-ordered lattices like NiPSe₃ intrinsically favor strong orbital responses, leading to voltages in the microvolt range even under modest thermal gradients. This insight enables predictive materials design: by maximizing magnon orbital moment and band hybridization, researchers can engineer magnetic insulators that efficiently convert heat or electric fields into spin–orbit currents. The ability to manipulate magnons electrically carries profound technological promise. Devices based on this principle could transmit and process information without charge flow, drastically reducing energy dissipation. Moreover, because the formalism applies to both thermal and optical driving forces, it hints at opto-magnonic interfaces where light’s angular momentum can be converted into magnonic excitation and back—a pathway toward hybrid quantum technologies. The work also implies that materials with large magnon OAM could serve as platforms for exploring dynamic magnetoelectric coupling and potentially new states of correlated matter governed by spin–orbit entanglement. On a conceptual level, Professor Doty’s team demonstrates that the magnon Nernst effects are not isolated thermal curiosities but manifestations of a universal electrodynamic principle linking angular momentum transport to polarization. Their unified quantum model enables experimentalists to quantify and predict these effects with unprecedented accuracy. Future efforts may exploit this insight to realize magnon-based sensors, transducers, and memory elements controllable by electric fields rather than magnetic ones.