Structure and magnetic properties of nanocrystalline CaB6 films deposited by magnetron sputtering

• Nanocrystalline CaB6 films were deposited by dc magnetron sputtering.
• CaB6 films showed weak ferromagnetism.
• The relationship between the structure and the magnetic properties was explored.
• The ferromagnetism was caused by structure defects rather than alien iron.

The nanocrystalline CaB6 films with different thickness were fabricated using DC-magnetron sputtering. The structure and the magnetic properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectrometer (SEM–EDS) and alternating gradient magnetometer (AGM). All films shows the lattice expansion and the (1 0 0) texture. With increasing of film thickness, the degree of lattice expansion decreased due to the intercalated argon atoms and the excess boron atoms. However, the grain size changed in the opposite tendency. The thinnest film (t = 500 nm) exhibited the greatest moment 3.76 × 10−8 A m2, resulting in a magnetization of 11.36 × 103 A/m. Defects aroused mainly by the lattice expansion and the grain boundaries were likely origin of the magnetism.