Reduced substrate clamping effect and evidence of shape memory behavior in vertically aligned Ni-Mn-In nanorod arrays
Kirandeep Singh, Shuvam Pawar, Davinder Kaur
Volume 2, Issue 1, Page 10-15, Year 2017 | DOI: 10.5185/amp.2017/104
Keywords: Thin films, X-ray diffraction, magneto-caloric, magnetization, nanorods.
Abstract: Silicon integrated vertically aligned Ni-Mn-In nanorod arrays having ~100 nm length were investigated for shape memory behavior and magnetocaloric effect. The room temperature X-ray diffraction (XRD) patterns revealed the (220) oriented pure austenitic cubic phase growth of Ni–Mn–In nanorods. The systematic thermo-magnetic (M-T) plots, resistance vs. temperature (R-T) measurements, as well as the negative slope of Arrott plots (H/M vs. M2) curves revealed the existence of significant shape memory effect in 100 nm Ni-Mn-In rods between 230 ≤ T≤ 294 K region. The formation of narrow hysteresis between field cooled (FC) and field warm (FW) curves in contrast to previous studies which reported broadness in the martensitic transformation temperature regime with decreasing thickness , can be ascribed to reduced substrate clamping effect due to vertically aligned growth of Ni-Mn-In. The magnetocaloric curves evaluated from M-H study indicates that large magnetic field magnitude dependent entropy change occurs in Ni-Mn-In rods, a maximum attainable ΔSM ~ 0.4 mJ/cc.K was observed at 275 K. Such vertically aligned growth of Ferromagnetic Shape Memory Alloys (FSMA’s) thin films over semiconductor substrate exhibiting significant shape memory behavior could prove useful in many MEMS/NEMS applications as well as opens possibility of futuristic self-cooled spintronics devices like magneto-electric random access memory (ME-RAM). Copyright © 2016 VBRI Press.