2025/05/20 by Ladislav Straka, Marek Vronka, Straka, Ladislav +9
Materials Science · #FOS: Physical sciences #Magnetic Properties of Alloys #Magnetic and transport properties of perovskites and related materials #Materials Science (cond-mat.mtrl-sci) #Shape Memory Alloy Transformations
paper · pdf · doi:10.48550/arxiv.2505.14096
openalex publication_date 2025/05/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The atomic topology and magnetic microstructure of individual, highly mobile Type I and Type II twin boundaries in 10M Ni-Mn-Ga martensite were investigated by transmission electron microscopy (TEM). The twin boundaries established in a bulk single crystal showed twinning stresses of ~1 MPa for Type I and ~0.1 MPa for Type II twin boundaries. TEM lamellae with a (010) cross-section, their c-axis (easy-magnetization direction) lying in-plane, were prepared by focused ion-beam milling, each containing a single twin boundary of specific type. High-resolution TEM confirmed an atomically sharp Type I twin boundary oriented along the rational (101) plane. The Type II boundary was also atomically sharp, apart from occasional single-atomic-plane steps. This contrasts with previous suggestions of its diffuse nature. Lorentz TEM showed 180° domain walls within martensite variants. The magnetic induction reorients sharply on both twin boundaries, forming 90°-like magnetic domain walls that follow the c-axis easy-magnetization direction.