Magnetic circular x-ray dichroism in Ce intermetallic compounds

Abstract

Magnetic circular x-ray dichroism (MCXD) studies at L2 3 absorption edges in intermediate-valence (IV) compounds CeFez, Ce(Feo sCop g)2 CeCo"CezCo, 7, and trivalent 4f ' systems (CeRuzGe2, Ce3A1», CePd, CeFe2H3 8) at the Ce L2 3 edges are presented. The comparison with reference compounds (La, Lu, Hf, Cxd) confirms the existence, in such IV systems, of an ordered Sd magnetic moment on the Ce site antiferromagnetically coupled with the 3d Fe (Co) moment. Moreover, this study suggests, provided the 4f orbital moment is almost quenched, the existence of a simple proportionality between the MCXD intensity and the magnetic moment of the probed atom. For instance the MCXD method leads to a Ce Sd magnetic moment in CeFe~of about 0.3Sp& antiferromagnetically coupled with the 3d Fe moment, in good agreement with band-structure calculations. The MCXD applications in Ce(Fe, Co)2 and CeFe2H" permit us to define precisely the electronic structure of Ce in such compounds. Particularly we will show that MCXD experiments at the L2 3 absorption edges of Ce are able to yield valuable information on the degree of hybridization of the 4f electrons in the ground state. Indeed, systematic comparison between the MCXD signals of IV and normal trivalent Ce compounds reveals the extreme sensitivity of the L2 3 MCXD experiments to the degree of localization of the 4f electrons.

Magnetism in gallium-dopedCeFe2: Martensitic scenario

“…The T C = 230 K is almost lower by a factor of 3 as compared to that of LuFe 2 ͑T C = 610 K͒ with its full 4f shell and YFe 2 ͑T C = 545 K͒, which has no 4f electrons. 2,4 The saturation magnetic moment is also anomalously low ͑M s = 2.4 B / f.u.͒ as compared to that of LuFe 2 ͑M s = 2.9 B / f.u.͒. 2,4 Another interesting observation in CeFe 2 is the occurrence of antiferromagnetic fluctuations.…”

“…2,4 The saturation magnetic moment is also anomalously low ͑M s = 2.4 B / f.u.͒ as compared to that of LuFe 2 ͑M s = 2.9 B / f.u.͒. 2,4 Another interesting observation in CeFe 2 is the occurrence of antiferromagnetic fluctuations. 1 It has been reported that substitution of small amounts of elements such as Co, Al, Ru, Ir, Os, and Re stabilizes the low-temperature dynamic AFM phase in CeFe 2 .…”

Experimental and theoretical study of magnetic ordering and local atomic polarization in Ru-substitutedLu2Fe17

“…In the Lu-Fe intermetallic compound, Lu atoms may possess a non-intrinsic, induced magnetic moment originating from the hybridization effects of 5d-Lu states with the 3d states of magnetic transition metal matrix (see, e.g., theoretical and experimental results on LuFe 2 [36,37]). Because the L 2 , 3 XMCD signals are directly related to the spin polarization of the d final states (and determined by the selection rules) and act as a spin detector of the absorbing atom, the data in Fig.…”

“…A small DOS peak in the vicinity of E F is mostly of a spin-down character and is caused by the 12k and 6g atomic Fe positions (i.e., those in close proximity with Ru atoms), both having sharp edges in the p-DOS at the Fermi energy. 094420-7 [36,37]. A smaller average Lu moment is derived from the XMCD data at the maximum applied magnetic field of 3 T, M Lu = −0.072 μ B .…”

L 3 and M 4,5 absorption edges of intermediate valent cerium unravelled by resonant photoemission and resonant Auger spectroscopy

“…XAS at the L2,3 (ROhler, 1987) and lVh,5 (Kaindl, 1985) edges has been widely performed to study the electronic properties of rare earths (4f occupancy using phenomenological interpretation of the edge profiles (ROhler, 1987), or magnetism using X-ray Magnetic Circtflar Dichroism (XMCD) (Finazzi, 1995, Giorgetti, 1993, Kaindl, 1985. Resonance experiments are a new way to assign the main structure of the absorption edge to precise final electrolfic configurations, for relatively localized states.…”