The structural and magnetic properties of Y_n+1Co_3n+5B_2ncompounds investigated by neutron diffraction

Abstract

The crystal and magnetic structures of Yn+1Co3n+5B2n (n = 2, 3 and ∞) have been studied by high-resolution powder neutron diffraction. The results are compared to earlier measurements on YCo5 and YCo4B. A change in the regular stacking of the boron-containing plane along the c axis has been observed in the Y2Co7B3 sample. Very short Co–B distances are observed, indicating that strong bonds are formed between cobalt and boron. The YCo3B2 compound is paramagnetic down to 2 K. The magnetic structures of Y3Co11B4 and Y2Co7B3 confirm the large variety of cobalt magnetic moments obtained in these compounds. The magnetic behaviour of the Co(2c) atoms is not significantly affected by the substitution of boron for cobalt. Cobalt atoms with significantly reduced magnetic moments are found on the 3g and 6i2 sites in both Y3Co11B4 and Y2Co7B3. A relationship between the magnitude of the Co magnetic moment and the presence of boron in the neighbourhood of the cobalt atoms is proposed. The hybridization of the cobalt 3d electronic state with the boron 2p state is found to play a major role in the determination of the magnitude of the Co magnetic moment in the Yn+1Co3n+5B2n compounds.

The correlation between the electronic structure and elastic properties of nanolaminates

“…75 Y n+1 Co 3n+5 B 2n phases are built of YCo 5 layers, which are interleaved with n layers of YCo 3 B 2 .…”

“…75 For instance, YCo 4 B (n = 1) exhibits a saturation magnetization of 3.36 B /f.u. and the Curie temperature of 375 K, based on SQUID and susceptibility measurements.…”

Magnetic properties of Al–Gd–Ni orthorhombic compounds

“…The compound Ni 3 Al, known as a spin fluctuation system, has the 3d band almost filled with µ = 0.075 B /Ni [12], and NiAl compound is a Pauli paramagnet with the 3d band completely filled [13]. A similar effect of the 3d-2p hybridization on the 3d transition metal magnetic moment (Co magnetic moment) has been pointed out in the R-Co-B compounds [14][15][16][17][18]. The complete filling of the Ni 3d band was also evidenced in Al 16 GdNi 3 by X-ray photoelectron spectroscopy [8].…”

First principles calculations, neutron, and x-ray diffraction investigation of Y3Ni13B2, Y3Co13B2, and Y3Ni10Co3B2

“…Thus, neutron diffraction experiments performed on R nþ1 Co 3nþ5 B 2n (n ¼ 1, 2, 3 and infinity) have brought evidence on (i) the preferential occupation character of the 3d metal sites; 21,22 (ii) the dependence of the local cobalt magnetic moments on the details of the local environment, particularly on the presence of B atoms nearest neighbors (n.n. ), 23,24 and (iii) the reduction of exchange field at the R site due to the Co magnetic moment decrease in the boron containing phases, with respect to RCo 5 . 25 X-ray magnetic circular dichroism (XMCD) measurements performed at the Co K edge in YCo 4 B revealed a decrease in the amplitude of the XMCD signal relative to that of LaCo 5 , which was attributed to the decrease in both the purely atomic contribution and the contribution of the spin-orbit interaction.…”