2026/03/09 by Samuel Haeuser, R. K. Chan, Randall K. Chan +6
Materials Science · Physics and Astronomy · #Magnetic properties of thin films #Multiferroics and related materials #Topological Materials and Phenomena #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1002/advs.76799
openalex publication_date 2026/07/24 · openalex created_date 2026/07/25 · openalex updated_date 2026/07/30
ABSTRACT Resolving sub‐10 nm spin switching and the associated terahertz (THz) electrodynamics during the colossal magnetoresistance (CMR) transition is a definitive frontier in reaching the fundamental spatial, temporal, and energy‐dissipation limits of spin‐electronics. Yet, simultaneous control of high magnetic field, cryogenic environment, and nanometer resolution has remained an elusive benchmark for THz nanoscopy, leaving the local THz dynamics of these transitions largely unexplored. Here, we overcome these limitations by utilizing a custom‐built cryogenic magneto‐THz scattering‐type scanning near‐field optical microscopy (cm‐THz‐sSNOM) to resolve the near‐field THz spectroscopic evolution of the magnetic field‐driven CMR transition in a manganite single crystal. Our measurements provide a nanoscale visualization of the THz conductivity, capturing the moment that magnetic‐field‐induced spin switching triggers the transition from an antiferromagnetic insulator to a ferromagnetic metal. An ellipsoidal near‐field model reveals a multi‐scale transition initiated by 1–2 nm isolated spin‐flip sites at low magnetic fields, which coalesce into 15 nm conducting regions as the threshold field is approached. These results provide an nano‐THz view of CMR switching, establishing an analysis framework for mapping spin–charge–lattice–orbit–coupled dynamics at spatial scales that transcend the nominal sSNOM resolution.