Magnetic coercivity control by heat treatment in Heusler Ni-Mn-Ga(-B) single crystals

0509151 - FZÚ 2020 RIV GB eng J - Journal Article
Straka, Ladislav - Fekete, Ladislav - Rameš, Michal - Belas, E. - Heczko, Oleg
Magnetic coercivity control by heat treatment in Heusler Ni-Mn-Ga(-B) single crystals.
Acta Materialia. Roč. 169, May (2019), s. 109-121. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA ČR GA16-00043S; GA MŠMT(CZ) LO1409
EU Projects: European Commission(XE) 701867 - FUNMAH
Institutional support: RVO:68378271
Keywords : magnetic shape memory alloys * antiphase boundary * magnetic properties * coercivity * Ni-Mn-Ga
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 7.656, year: 2019
Method of publishing: Open access

The combination of enlarged magnetic coercivity and magnetic shape memory (MSM) functionality is essential for novel magnetomechanical effects in MSM alloys. We found that increasing the density of thermal antiphase boundaries (APBs) provides a method to increase the magnetic coercivity without deteriorating the MSM functionality. APB density was controlled by different heat treatments in Ni–Mn–Ga (–B) MSM single crystals with five-layered modulated martensite structure. Slow cooling ∼1 K/min of Ni–Mn–Ga through the B2′–L21 transition resulted in a low density ( < 1/micrometer) of APBs observed by magnetic force microscopy and low coercivity <2 mT. Water quenching resulted in fine magnetic and APB patterns and enlarged the coercivity to 24 mT at room temperature, and this further increased with decreasing temperature up to 41 mT at 10 K.
Permanent Link: http://hdl.handle.net/11104/0299923