Neutrons Point to Next-Generation Computer Memory Materials

Atomic structure of a mineral perovskite

CINS Scattering Spotlight: Dr Dalini Maharaj, TRIUMF

Source: Mitchell DiPasquale 
Image: Crystal structure of a mineral perovskite. (Wikimedia CC-BY-SA 3.0)

As our music and movie libraries grow and the number of apps we use multiplies, everyone wants faster devices with larger data storage. Former McMaster PhD student Dalini Maharaj studies novel magnetic materials that could very well usher in the next generation data storage technology, particularly in disk drive read-and-write heads. In principle, one could reduce the size of the data storage unit if the data density could be increased in these hard-disks. New kinds of quantum materials are needed to fulfil this promise.

“Of course, before these new technologies can be realized, much work needs to be performed to understand the properties of the candidate materials.” – Dr. Dalini Maharaj, TRIUMF Post-Doctoral Fellow

Dr. Maharaj’s PhD work involved the study of the quantum magnetic properties of crystalline materials via X-ray and neutron scattering methods. Working in Prof. Bruce D. Gaulin’s group at McMaster University, she synthesized novel materials which are theoretically predicted to exhibit exotic magnetic properties. This class of materials, referred to as the double perovskites, have phases that involve `frustrated` magnetic interactions, whereby the magnetic dipoles of the atoms cannot arrange themselves into a low energy configurations. Members of this family are widely studied as they are shown to exhibit a wide variety of unique properties including superconductivity, ferroelectricity and colossal magnetoresistance, the latter being a prime candidate for increasing the data density of hard drives. In particular, Dalini’s doctoral work involved the study of non-trivial arrangements of magnetic atoms in d-electron double perovskites which are driven by magnetic interactions that can only be theoretically analysed with advanced quantum mechanics.

Dr. Dalini Maharaj

Neutrons are an indispensable probe of the magnetic properties of materials as they are electrically neutral and they possess the property of spin. These properties enable neutrons to deeply penetrate matter and interact directly with the magnetic degrees of freedom in solid state materials. The energy spectra which are obtained from neutron scattering experiments provide important clues for identifying the magnetic ground state of the materials being investigated.

Most recently, Dalini’s neutron scattering studies on the cubic double perovskite materials led to discover the first instance of octupolar order in d-electron magnets. This discovery highlights the relevance of multipolar interactions in heavy d-electron magnets and consequently, the potential for the realization of novel materials for future applications.

Upon completing her PhD, Dalini remained in the field of neutron sciences and is currently completing a postdoctoral fellowship at TRIUMF, through the University of Windsor, studying potential targets and moderators for a future compact accelerator neutron source.

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