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Alloying antiferromagnetic Cr with ferromagnetic Ni forms an excellent starting point to design materials for various room temperature applications, such as spintronics, the magnetocaloric effect, and hyperthermia, thanks to its tunable Curie temperature, T C , and competing magnetic interactions. In this report, we present a comprehensive analysis of the relationships among film thickness, Cr surface segregation, and magnetic properties in nanocrystalline Ni 100−x Cr x (x = 5−15 at. %) thin films. We assess the impact of Cr segregation evolution on various magnetic transitions as the thickness and Cr doping level increase. These films exhibited ferromagnetic to paramagnetic transitions at higher temperatures and ferromagnetic to spin-glass transitions at low temperatures, which resulted in a phase diagram that differed from the bulk equilibrium phase diagram. Further, magnetometry and magnetic force microscopy were performed to investigate the magnetic anisotropy and magnetic domain structure as a function of film thickness. It is found that the perpendicular component of magnetic anisotropyled to a stripe domain structure in films with critical thicknesses above 20 nm. Substantial changes in the magnetization behavior of nanocrystalline Ni 100−x Cr x thin films within a few Cr at. % doping provide a means for adjusting both soft and hard magnetic component applications.

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A cryo-cooler based cryogenic test setup has been designed, fabricated, and tested. The setup incorporates two numbers of cryo-coolers, one for sample cooling and the other one for cooling the large magnet coil. The performance and versatility of the setup has been tested using large samples of high-temperature superconductor magnet coil as well as short samples with high current. Several un-calibrated temperature sensors have been calibrated using this system. This paper presents the details of the system along with results of different performance tests.