The magnetic properties of sputtered Pd_1-xMn_x films for thermometry and bolometry

The magnetic susceptibility of thin films and microstructures consisting of a Pd₁Mn_x alloy have been measured as a function of temperature and magnetic field. Sputtering from a 0.68% manganese target produced films with a concentration of approximately 0.90%, as judged by comparison with results from bulk PdMn sensitivity measurements. The thinnest films (thickness ≤ 1.0μm) show significant domain scale noise below the Curie Temperature, T_c, while thicker films (thickness ≥ 10 μm) show reliable non-hysteretic behavior throughout the temperature range of interest. The thin films show the effects of demagnetization with the field perpendicular to the surface, but a fine screen in this orientation shows no evidence of saturation and a predictable decrease in sensitivity due to demagnetization. These films will serve as the thermometric element in a new class of bolometers and thermometers for fundamental physics applications.