Agradecimentos: This work was supported by FAPESP (SP-Brazil) under Contracts No. 2009/10264-0, No. 2011/19924-2, No. 2011/24166-0, No. 2012/10675-2, and No. 2012/17562-9. Parts of this research were carried out at the light source PETRA III at DESY, a member of the Helmholtz Association (HGF). Work at Argonne National Laboratory is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC-02-06CH11357. We would like to thank R. D. Reis and C. S. B. Dias for their assistance in macroscopic measurements and J. W. Kim for his assistance at beam line 6-ID-B. We are indebted to D. Reuther, R. Kirchhof, and H.-C. Wille for their assistance with the electromagnet at P09/DESY Ver menos

Abstract: We investigate the magnetic and electronic properties of the GdT2Zn20 (T = Fe and Co) compounds using x-ray resonant magnetic scattering (XRMS), x-ray absorption near-edge structure (XANES), and x-ray magnetic circular dichroism (XMCD). The XRMS measurements reveal that GdCo2Zn20 has a commensurate antiferromagnetic spin structure with a magnetic propagation vector (tau) over right arrow = (1/2, 1/2, 1/2) below the Neel temperature (T-N similar to 5.7 K). Only the Gd ions carry a magnetic moment forming an antiferromagnetic structure with magnetic representation Gamma(6). For the ferromagnetic GdFe2Zn20 compound, an extensive investigation was performed at low temperature and under magnetic field using XANES and XMCD. A strong XMCD signal of about 12.5% and 9.7% is observed below the Curie temperature (T-C similar to 85K) at the Gd L-2 and L-3 edges, respectively. In addition, a small magnetic signal of about 0.06% of the jump is recorded at the Zn K edge, suggesting that the Zn 4p states are spin polarized by the Gd 5d extended orbitals Ver menos