The innovation engine for new materials

Maryann Valerio

Maryann Valerio, Physics, Mount Holyoke College




Mount Holyoke College


Linus Kautzsch

Faculty Sponsor(s): 

Ram Seshadri

Faculty Sponsor's Department(s): 


Project Title: 

Exploring Structure and Magnetism of Potential Skyrmion Hosts in the Filled β-Manganese Structure Cu1.5M0.5(Pt0.7Cu0.3)3B (M = Fe, Ni, Zn)

Project Description: 

Skyrmions are chiral magnetic nanostructures comprised of electron spins aligned in a  topologically protected, vortex-like formation. Skyrmion hosts are a promising materials for low-power, high-information-density spintronic devices such as magnetic racetrack memory. A previous study found room-temperature skyrmions in the CoxZnyMnz system, which crystallizes the β-Manganese structure. This noncentrosymmetric structure allows long range Dzyaloshinskii-Moriya (DM) interactions that can enable the formation of skyrmions. Here, we report on the modifications of another recently-discovered compound with the filled β-Manganese structure (interstitials occupied by B atoms), Cu2(Pt0.7Cu0.3)3B. We doped the system to form Cu1.5M0.5(Pt0.7Cu0.3)3B (M = Fe, Ni, Zn). Fe and Ni were expected to yield a magnetic systems which might host skyrmions. Zn was added to attempt to synthesize a new superconductor in this class.  The crystal structure was confirmed as β-Manganese for all three samples by x-ray diffraction (XRD); magnetic properties were characterized by vibrating sample magnetometry (VSM/SQUID) and morphology by scanning electron microscopy (SEM); composition of main and secondary phases was determined through energy-dispersive x-ray spectroscopy (EDS). The iron compound is a chiral magnet with a Curie transition temperature at 300 K and may be a low-temperature spin glass. The compound shows a second magnetic transition around 600 K resulting from an iron-rich impurity. The nickel and zinc compounds are paramagnets; the zinc compound had a minority (< 0.1%) superconducting phase. Though no skyrmions could be observed, the results demonstrate that the β-Manganese structure is preserved with doping; in addition, a new chiral magnet (M = Fe) was discovered.