Ferromagnetic resonance study on a single crystal of martensitic Heusler compound

You-Sheng Chen^1*, J. G. Lin^1,2, S. Singh³, C. Fesler³

¹Center for condensed matter sciences, National Taiwan University, Taipei, Taiwan
²Center for Atomic Initials for New Materials, National Taiwan University, Taipei, Taiwan
³Chemical Physics of Solids, Max Planck Institute, Dresden, Germany

* Presenter:You-Sheng Chen, email:youshengchen@ntu.edu.tw

In the past two decades, NiMn-based martensitic Heusler compounds attract intense interest for their properties of magnetically controlled shape memory, large magnetic field induced strain (MFIS), and magnetocaloric effects. The large MFIS are attributed to the strong magnetic anisotropy energy (MAE) which exceeds the elastic energy required for twining boundary motion and phase transition. To determine MAE with the conventional method of magnetic hysteresis, the single variant structure is required, regardless the fact that the nature of monoclinic transition from austenite is multi-variant. In this work, ferromagnetic resonance (FMR) is applied to identify the magnetic anisotropy in a single crystal Ni₅₀Mn₃₆In₁₄. Since FMR spectrum can reveal the anisotropy fields of all orientations of multi-variant twining, the single-variant is not an essential condition for FMR analysis. FMR spectrum displays the multi-variant domains in the single crystal. During the structural transition, the Martensite and Austenite phases are found coexistent within a temperature range of 230 ~ 240 K. Our results reveal the evolution of twining boundary motion during the Martensite to Austenite transition.

Keywords: Magnetic Anisotropy, Heusler alloy, Martensite transition