Emergence of Magnetic Field-Modulated Negative Magnetoresistance in Manganese Phosphide Nanorod Thin Films

Manganese phosphide (MnP) is a complex magnetic material with multiple exotic magnetic phases. Here we report the temperature dependent charge and spin transport properties of a MnP nanorod thin film over a wide temperature range (2 K < T < 350 K). The MnP nanorod thin films of ~100 nm thickness were grown on Si substrates at 500 °C using molecular beam epitaxy (MBE). The temperature dependent resistivity (ρ) data for the MnP film exhibit a metallic behavior (dρ/dT > 0) over the entire measured temperature window. However, negative magnetoresistance (MR) up to 12 % is observed for the MnP film at low temperatures (< 100 K) under the application of high magnetic fields up to 8 T. With reference to the MnP single crystal whose stable helical (screw) phase develops below 47 K, the MR(H) dependence reveals a high field-manipulated CONE + FAN phase coexistence in the MnP film. This important finding pinpoints a correlation between the transport and magnetism in helical magnetic systems like MnP for perspective spintronics applications.