Magnetic and Structural Properties of Rapidly Quenched Tetragonal Mn3-xGa Nanostructures

Journal Article · Mon Jul 01 00:00:00 EDT 2013 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/TMAG.2013.2244856· OSTI ID:1211421

Huh, Y; Kharel, P; Shah, VR; Krage, E; Skomski, R; Shield, JE; Sellmyer, DJ

Nanostructured Mn3-x Ga ribbons with x = 0, 0.4, 0.9 and 1.1 were prepared using arc-melting, melt-spinning and annealing. As-spun samples crystallized into hexagonal D0(19) and cubic L2(1) Heusler crystal structures based on the concentration of Mn in Mn3-xGa. Upon vacuum-annealing the samples at 450 degrees C for about 50 hours, both the hexagonal and cubic structures transformed into a tetragonal D0(22) structure. High-temperature x-ray diffraction and high-temperature magnetometry showed that the samples with low Mn content (Mn-1.9 Ga and Mn-2.1 Ga) retain their tetragonal structure up to 850 K but the samples with high Mn concentrations (Mn-2.6 Ga and Mn-3.0 Ga) undergo a structural phase transition from tetragonal to hexagonal phases around 800 K. The magnetic properties of Mn3-x Ga ribbons were very sensitive to Mn concentration, where the magnetization and anisotropy energy increased and the coercivity decreased as x increased from 0 to 1.1. Although the Curie temperatures of Mn-2.6 Ga and Mn-3.0 Ga samples could not be determined because of the structural phase transition, the Curie temperature decreased with increasing x in Mn3-x Ga. The maximum magnetization of 57 emu/g (300 emu/cm(3)) and the coercivity of 6.5 kOe were measured in the Mn-1.9 Ga and Mn-3.0 Ga ribbons, respectively.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: DE-AR0000046
• OSTI ID: 1211421
• Journal Information: IEEE Transactions on Magnetics, Vol. 49, Issue 7; ISSN 0018-9464
• Country of Publication: United States
• Language: English