Magnetic control of reflectionless states and an intrinsic-mode exceptional point in a magnon-phonon coupling system

Mingyuan Ma; Jiongjie Wang; Chong Chen; Weiqi Du; Liyang Liao; Yanzhang Cao; Peisen Liu; Boyuan Xiao; Deqi Tao; Shixuan Liang; Sulei Fu; Jiang Xiao; Cheng Song; Feng Pan

arXiv · 2610.41851

Magnetic control of reflectionless states and an intrinsic-mode exceptional point in a magnon-phonon coupling system

Mingyuan Ma·Jiongjie Wang·Chong Chen·Weiqi Du·Liyang Liao·Yanzhang Cao·Peisen Liu·Boyuan Xiao·Deqi Tao·Shixuan Liang·Sulei Fu·Jiang Xiao·Cheng Song·Feng Pan

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Abstract

Reflectionless states (RLs) and exceptional points (EPs) are hallmark singular responses of non-Hermitian systems, with potential applications in sensing, wave control, and energy manipulation. Yet, realizing and independently tuning these states in a compact integrated platform remains challenging. Here, we demonstrate two-dimensional magnetic control of RLs and EPs in an on-chip magnon-phonon system based on a FeGaB-32 degree-YX-LiNbO3 heterostructure. The magnetic-field magnitude tunes the magnon-phonon detuning, driving a low-loss reflection zero across the real-frequency axis and producing two field-tunable RLs with near-vanishing reflection. A closed contour of the experimentally measured complex S11 around the reflection-zero singularity accumulates a -2pi phase winding. Independently, rotating the magnetic field tunes the magnon-phonon coupling strength, driving the intrinsic magnon-phonon eigenmode spectrum across an exceptional point, identified by the exchange between real-part and imaginary-part eigenvalue splitting. A unified one-port input-output model connects the measured complex S11 response to the field-driven dynamics of the reflection zeros and the angle-tuned intrinsic magnon-phonon eigenmodes. These results establish a magnetically programmable non-Hermitian magnon-phonon platform for integrated wave control and compact vector magnetic sensing.

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Mingyuan Ma, Jiongjie Wang, Chong Chen, Weiqi Du, Liyang Liao, Yanzhang Cao, Peisen Liu, Boyuan Xiao, Deqi Tao, Shixuan Liang, Sulei Fu, Jiang Xiao, Cheng Song, Feng Pan. 2026-10-30. Magnetic control of reflectionless states and an intrinsic-mode exceptional point in a magnon-phonon coupling system. https://arxiv.org/abs/2610.41851

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