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arXiv · 2505.14096

Atomic Topology and Magnetic Microstructure of Highly Mobile Type I and Supermobile Type II Twin Boundaries in 10M Ni-Mn-Ga Single Crystal

Ladislav Straka·Marek Vronka·Jan Maňák·Petr Veřtát·Hanuš Seiner·Oleg Heczko
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Abstract

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{\deg} domain walls within martensite variants. The magnetic induction reorients sharply on both twin boundaries, forming 90{\deg}-like magnetic domain walls that follow the c-axis easy-magnetization direction.

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Ladislav Straka, Marek Vronka, Jan Maňák, Petr Veřtát, Hanuš Seiner, Oleg Heczko. 2025-05-20. Atomic Topology and Magnetic Microstructure of Highly Mobile Type I and Supermobile Type II Twin Boundaries in 10M Ni-Mn-Ga Single Crystal. https://arxiv.org/abs/2505.14096

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