Emergence of Intergranular Tunneling Dominated Negative Magnetoresistance in Helimagnetic Manganese Phosphide Nanorod Thin Films

TL;DR

This study investigates charge transport and magnetoresistance in MnP nanorod thin films, revealing intergranular tunneling as the dominant mechanism behind negative magnetoresistance below 50 K, linked to the helimagnetic state.

Contribution

It provides new insights into the charge and spin transport properties of helimagnetic MnP nanorod films, highlighting intergranular tunneling as a key factor in their magnetoresistance behavior.

Findings

Large negative magnetoresistance up to 12% below 50 K

Metallic resistivity behavior across 2-350 K

Magnetic field influences phase coexistence

Abstract

Helical magnets are emerging as a novel class of materials for spintronics and sensor applications; however, research on their charge and spin transport properties in a thin film form is less explored. Herein, we report the temperature and magnetic field dependent charge transport properties of a highly crystalline MnP nanorod thin film over a wide temperature range (2-350 K). The MnP nanorod films of 100 nm thickness were grown on Si substrates at 500 oC using molecular beam epitaxy. The temperature dependent resistivity data exhibits a metallic behavior over the entire measured temperature range. However, large negative magnetoresistance of up to 12% is observed below 50 K at which the system enters a stable helical (screw) magnetic state. In this temperature regime, the MR(H,T) dependence seems to show a magnetic field manipulated phase coexistence. The observed magnetoresistance is dominantly governed by the intergranular spin dependent tunneling mechanism. These findings pinpoint a correlation between the transport and magnetism in this helimagnetic system.