Long-range order parameter of single L10-FePd nanoparticle determined by nanobeam electron diffraction: Particle size dependence of the order parameter

Abstract

Fabrication of oriented L 1 0 -FeCuPd and composite bcc -Fe ∕ L 1 0 -FeCuPd nanoparticles: Alloy composition dependence of magnetic properties J. Appl. Phys. 99, 08N706 (2006); 10.1063/1.2165604 Determination of order parameter of L 1 0 -Fe Pd nanoparticles by electron diffraction J. Appl. Phys. 97, 084301 (2005); 10.1063/1.1861987 Fabrication of exchange-coupled α -Fe ∕ L 1 0 -FePd nanocomposite isolated particlesThe long-range order ͑LRO͒ parameter ͑S͒ of single isolated L1 0 -FePd nanoparticle was determined by quantitative analysis of nanobeam electron diffraction ͑NBD͒ intensities and intensity calculations considering the multiple scattering of electrons. The obtained order parameters of the nanoparticles larger than 8 nm are distributed around the mean LRO parameter ͑S = 0.79͒ which was determined by selected area electron diffraction intensity analysis, while the parameters slightly decreased gradually as the particle size decreased below about 8 nm ͑S = 0.60-0.73͒. The low degree of order in very small particles is responsible for the coercivity decrease of the L1 0 nanoparticles in smaller-sized regions. Quantitative NBD intensity analysis is quite useful for the determination of the LRO parameter of individual L1 0 -FePd single crystalline nanoparticle. Experimental conditions required for NBD analysis are presented in detail and the possible experimental errors of the determined LRO parameters are discussed.

Magnetostriction properties of FePd thin films: Dependence on microstructure

“…Alloys in the range of Fe-49 at% Pd to Fe-58 at% Pd, which crystallize in the L1 0 structure [1], show a high magneto-crystalline anisotropy, the tetragonal c-axis being the easy axis of magnetization The long-range order (LRO) parameter S decreases with increasing annealing temperature [2] and annealing of bulk specimens at 733 K for 15 h leads to S = 0.71 [3]. Recent studies showed that the order parameter is further drastically reduced, when the grain size drops below 8 nm [4]. In a two-phase alloy the effect of the order parameter has to be distinguished from the effect resulting from the volume fraction of the two-phases [5].…”

“…It is well accepted that the L1 0 -ordering is accompanied by magnetic domain ordering and increases the magnetic susceptibility [3]. It is known that nano-particles prevent magnetic domains from changing their direction or size [4,8]. Magnetostric- tion has successfully been applied for actuators [6] and hydrogen absorption detectors [9,10].…”

Particle size dependence of atomic ordering and magnetic properties of L10-FePd nanoparticles

“…According to our recent study on FePd nanoparticles, the LRO parameter gradually decreased as the particle size decreased below about 8 nm [2]. Hence, a relationship between the magnetic properties and the particle size especially in the size region less than 8 nm is an important issue for high-density magnetic recording as well as scientific interests.…”

Atomic structure imaging of L1-type FePd nanoparticles by spherical aberration corrected high-resolution transmission electron microscopy

“…2 The evolution of the chemical order in FePd nanoparticles has been studied by high-resolution transmission electron microscopy ͑HRTEM͒ and electron diffraction, 3,4 while the size dependence of the long-range order has been examined by nanobeam electron diffraction. 5 However, the detailed atomic structure and a possible size limit of long-range atomic ordering are not yet understood.…”