Atomic-to-Mesoscale Twinning Effects and Strain-Driven Magnetic States in an Anisotropic 2D Ferromagnet FePd₂Te₂.

Abstract

Strain engineering offers a compelling route to modulate magnetism in two-dimensional (2D) materials, yet most approaches rely on externally applied strain. An in-plane anisotropic 2D-layered ferromagnet FePd₂Te₂ provides a suitable platform to study intrinsic strain-magnetism coupling due to its twinning domains. Here, we report spatially modulated internal compressive/tensile(C/T) strain regions in FePd₂Te₂ and their strong impact on local magnetic properties in real space by using atomic/magnetic force microscopy (AFM/MFM) combined with scanning tunneling microscopy (STM). Field- and strain-dependent spin transformations reveal the modulation of its intrinsic C/T regions. Notably, C regions retain intact Fe zigzag chains and exhibit larger, abruptly switching magnetic moments, while T regions display fragmented chains with reduced, gradually rotating spins. The intrinsic strain-induced intact ferromagnetic (FM), field-induced polarized-FM states, and their transitions are comparatively discussed during magnetic measurements. Temperature- and field-dependent evolution are further investigated in the FM and paramagnetic (PM) states and summarized to obtain an H-T phase diagram of FePd₂Te₂. Our work provides key results for understanding real-space tunable magnetic states through internal structural heterogeneity and suggests potential strategies for manipulating intrinsic strain-engineered magnetic devices.