Magnetic moments and spin structure in single-phase B20 Co1+xSi1−x (x = 0.043)

Abstract

Neutron powder diffraction (NPD) and x-ray magnetic circular dichroism (XMCD) spectroscopy are employed to investigate the magnetism and spin structure in single-phase B20 Co1.043Si0.957. The magnetic contributions to the NPD data measured in zero fields are consistent with the helical order among the allowed spin structures derived from group theory. The magnitude of the magnetic moment is (0.3 ± 0.1) μB/Co according to NPD, while the surface magnetization probed by XMCD at 3 kOe is (0.18–0.31) μB/Co. Both values are substantially larger than the bulk magnetization of 0.11 μB/Co determined from magnetometry at 70 kOe and 2 K. These experimental data indicate the formation of a helical spin phase and the associated conical states in high magnetic fields.