‘Anti-symmetric Compton scattering in LiNiPO4: Towards a direct probe of the magneto-electric multipole moment’
Open Research Europe presents an interview with Sayantika Bhowal, one of the co-authors of ‘Anti-symmetric Compton scattering in LiNiPO4: Towards a direct probe of the magneto-electric multipole moment’, in this month’s Research Spotlight. Read on to find out more about the research.
Can you share a summary of your Research Article?
Magnetic materials have been used since the early days of our civilization for navigation and have affected most modern devices. Similarly to the magnetic dipoles of a magnet (the north and south poles), are electric dipoles that are made of positive and negative charges.
Materials containing both electric and magnetic dipoles are quite rare and are actively researched because of their huge technological prospects, as well as their intriguing fundamental physics. In particular, the basic electro-magnetic building blocks of such materials, made of composites of electric and magnetic dipoles, are of significant interest. They are likely to be related to exotic behaviors, such as superconductivity and other unusual electrical and magnetic properties.
In our Research Article, we propose an advanced experimental technique for detecting one of such composites. This is the so-called magnetoelectric multipole moment, using high-energy x-ray beams.
What inspired you to investigate this?
In crystalline solids, the different degrees of freedom of an electron may become entangled to form composites that can give rise to exotic properties. For example, the electric dipole (corresponding to the charge degree of an electron) and the magnetic dipole (relating to the spin degree of an electron) are coupled to form a composite which is known as a magnetoelectric toroidal moment.
While the magnetoelectric toroidal moment has displayed many exotic properties, such as electrical control of magnetism (magnetoelectric effect), superconductivity (conduction of electrons with no resistance), and dark matter, it is challenging to detect experimentally as it often escapes conventional analytical techniques.
Composites like the magnetoelectric toroidal moment that cannot be detected by conventional analytical techniques are known as “hidden order”. Understanding hidden order allows us to recognize many unconventional properties of magnetoelectric materials.
We were able to show that, theoretically, the technique of Compton scattering should be sensitive to the particular hidden order of a magnetoelectric toroidal moment. So, we were very happy when our colleagues were able to carry out the practical experiment.
What were the outcomes of your research?
One main finding was that hidden order can theoretically be detectable using Compton scattering and lithium nickel phosphate (LiNiPO4) – a material with hidden order – was a suitable material to test this analytical technique. Although the experimental data was in line with our predictions, the resolution was not high enough to definitively show the detection of hidden order. So, a second attempt is motivation for future experiments with either different materials or higher resolution.
Why is open research important to you?
We think that making the data and all the details available is very important, particularly in this case, where the measurements were promising but did not yield a positive end result. We hope that our work will motivate others to pursue this problem, and we want them to be able to benefit from our experience. We might also save people time trying approaches that didn’t work for us.
Often, journals are not interested in negative results. In our opinion, these are just as important as positive results for scientific progress! Publishing negative results can be a good scientific practice and we are very happy that Open Research Europe appreciates this.
What are your next steps?
Composites made of electric and magnetic dipoles are responsible for many interesting properties of materials, while their experimental detection is very challenging. In our Research Article, we proposed an advanced experimental technique for detecting these composites using high-energy x-ray beams.
Moving forward, we are trying to identify materials with hidden order that have a stronger response to Compton scattering. On the experimental side, we are thinking about how we could re-design the experiment to have increased sensitivity of this analytical technique in order to detect hidden order.
Want to find out more? Read the article here.
