Single Domain Co2fega Nanoparticles with High Crystalline Order Synthesized by Template-Less Chemical Method

Single-domain Fe2CoGa0.5Al0.5 Heusler alloy nanoparticles with enhanced properties

“…These defects increase t, which subsequently lowers the M s of the nanoparticles in comparison to the bulk M s (and theoretical M t ). The t value corresponding to the synthesized Fe 2 CoGa 0.5 Al 0.5 nanoparticles determined following the procedure reported in previous works, 19,20,39 is 0.11 nm at 5 K (and 0.12 nm at 300 K), explains small deviation in experimental M s from estimated M t . M t evaluated using the Slater Pauling rule (i.e., M t = Z t À 24, where Z t denotes the total number of valence electrons) is 4.0 m B f.u.…”

“…For high anisotropic materials, the single-domain to multi-domain critical size D cr , 54 can be evaluated using Bloch's T 3/2 law for temperature dependent M s measurements [55][56][57] at low temperatures. 58 Following the procedure laid down in earlier reports, 19,20,39 D cr for Fe 2 CoGa 0.5 Al 0.5 nanoparticles was estimated to be 87 nm (i.e. D cr 4 D v ), indicating them to be single-domain nanoparticles.…”

“…À1 at 300 K, respectively. The effective anisotropy constant (K eff ) estimated from law of approach to saturation, 45 as per reported procedure, 19,20,39 indicate high values (K eff = 8.29 Â 10 6 erg cc À1 at 5 K and 7.89 Â 10 6 erg cc À1 at 300 K). Xu et al 35 and Nehla et al 32 also reported such high K eff for other HA nanoparticles.…”

“…The quality factor Q, defined by Brown, 52 can be utilized to define high (for Q 4 0.1) and low anisotropic materials (for Q o 0.1). 52,53 Q = 1.28 at 5 K (Q = 1.23 at 300 K) estimated for the synthesized Fe 2 CoGa 0.5 Al 0.5 nanoparticles according to procedures specified in earlier reports 19,20,39 categorizes it as a high anisotropic material. For high anisotropic materials, the single-domain to multi-domain critical size D cr , 54 can be evaluated using Bloch's T 3/2 law for temperature dependent M s measurements [55][56][57] at low temperatures.…”