Influence of Thickness and Magnetic Field on Magnetic Ordering Temperatures in Holmium Thin Films

Influence of thickness and magnetic field on magnetic ordering temperatures is reported. The X-ray diffraction of Ho films confirmed their preferential crystal orientation and revealed diffraction peaks originating from the hcp structure of Ho and those from inessential holmium dihydride content. Secondary ion mass spectroscopy showed a very homogeneous distribution of holmium in thin films. Electrical resistance measurements on Ho films in the thickness range from 98 nm to 215 nm showed a "knee-like" resistance anomaly near the $T_N$. The $T_N$ value of these films decreased with decreasing film thickness. Magnetic field applied parallel to the thin film plane caused an increasing suppression of the $T_N$ value up to 5 K with increasing flux density value up to 5 T.