Magnetism and electron transport of MnyGa (1 < y < 2) nanostructures

Authors

Yung Huh, University of Nebraska-LincolnFollow
Parashu Kharel, University of Nebraska-LincolnFollow
Shah R. Valloppilly, University of Nebraska-LincolnFollow
XINGZHONG LI, Nebraska Center for Materials and NanoscienceFollow
Ralph Skomski, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

2013

Citation

JOURNAL OF APPLIED PHYSICS 114, 013906 (2013); DOI: http://dx.doi.org/10.1063/1.4812561

Comments

Copyright 2013 AIP Publishing LLC. Used by permission

Abstract

Nanostructured Mn_yGa ribbons with varying Mn concentrations including Mn_1.2Ga, Mn_1.4Ga, Mn_1.6Ga, and Mn_1.9Ga were prepared using arc-melting and melt-spinning followed by a heat treatment. Our experimental investigation of the nanostructured ribbons shows that the material with y = 1.2, 1.4, and 1.6 prefers the tetragonal L1₀ structure and that with y = 1.9 prefers the D0₂₂ structure. We have found a maximum saturation magnetization of 621 emu/cm³ in Mn_1.2Ga which decreases monotonically to 300 emu/cm³ as y reaches 1.9. Although both the L1₀- and D0₂₂-Mn_yGa samples show a high Curie temperature (T_c) well above room temperature, the value of T_c decreases almost linearly from 702K for Mn_1.9Ga to 551K for Mn_1.2Ga. All the ribbons are metallic between 2K and 300K but the Mn_1.2Ga also shows a resistance minimum near 15K. The observed magnetic properties of the Mn_yGa ribbons are consistent with the competing ferromagnetic coupling between Mn moments in the regular L1₀-MnGa lattice sites and antiferromagnetic coupling with excess Mn moments occupying Ga sites.