Paramagnetic-to-antiferromagnetic phase transformation in sputter-deposited Ni-Mn thin films

Abstract

Sputter-deposited, equiatomic Ni-Mn thin films were observed to possess a metastable, nanocrystalline, chemically disordered, fcc (A1) structure. Grain growth and a phase change to a chemically ordered, antiferromagnetic L1 0 structure were identified by x-ray diffraction (XRD) and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) experiments revealed exothermic signals that correspond to the grain growth and phase transformation reactions. The enthalpy of transformation for the A1 to L1 0 phase change was calculated as Ϫ3.5 kJ/mol, which agrees with thermodynamic modeling. An activation energy of 139 kJ/mol was calculated for the phase transformation by the Kissinger method.

Induced ordering in electrodeposited nanocrystalline Ni–Mn alloys

“…% Ni. The component energy values obtained for our samples is much higher than those obtained by others 18,39 for sputter deposited Ni-Mn film for a transformation to L1 0 structure, and the total energy is somewhat higher than the calculated enthalpies for alloy formation. 44 This higher value may be due to the nature of alloy formation in an electrodeposition technique and the process as well as extent of ordering taking place in our samples.…”

“…The thermal behavior of these electrodeposited samples differs considerably from those of Ni 3 Si, Ni 3 Al milled alloys 15,16 and sputtered Ni-Mn thin films. 18,39 All the DSC thermographs except for the case of 76.2 at. % Ni ͓Fig.…”

Crystallization Kinetics and Structure Evolution during Annealing of Ni-Co-Mn-In Powders Obtained by Mechanical Alloying

“…Table 3 presents the phase transformation activation energies of the Ni-Mn-Z (In, Ga) alloys (powders, thin films) consisting of amorphous or “amorphous-like” phases. In NiMn films obtained by magnetron sputtering, usually, the amorphous (or “amorphous-like”) phase transforms into fcc phase followed by fcc → L1 0 [ 18 , 19 ]. However, powders produced by high-energy grinding reveal different sequences of phase transitions during annealing.…”

“…Some researchers described the crystallization kinetics of amorphous Ni-Mn or Ni-Mn-Sn thin films produced by the magnetron sputtering technique [ 17 , 18 , 19 , 20 ]. Generally, during annealing, the phase transitions of amorphous films proceed as follows: amorphous → fcc → L1 0 .…”

Disorder–order phase transformation in sputter deposited Pd3In thin films

“…Sputtering deposition, one of the widely used thin films preparation methods, can also lead to the formation of metastable phases. For example, metastable or amorphous phases were also found in the sputter deposited NiMn [4][5][6], PtMn [7], PtPdMn [8], and Ni 3 Al [3,9] films. While stoichiometric Pd 3 In is stable up to 1223 • C [10], it was found in the previous studies [11][12][13] that Pd 3 In alloys with ordered tetragonal structure transformed into disordered face centered cubic (fcc) phase by plastic deformation and became ordered upon subsequent annealing.…”