Scientists use budget tech to probe long-standing physics mystery

Account subscription benefits alongside Premium Stories, Editorials, Opinions and more. Unlock these with Subscription

The View From India Looking at World Affairs from the Indian perspective.

First Day First Show News and reviews from the world of cinema and streaming.

Today's Cache Your download of the top 5 technology stories of the day.

Data Point Decoding the headlines with facts, figures, and numbers

Health Matters Ramya Kannan writes to you on getting to good health, and staying there

The Hindu On Books Books of the week, reviews, excerpts, new titles and features.

IIT-Delhi researchers have found that the Klemens model has ‘important limitations when applied to metals’. | Photo Credit: Special arrangement

When a team at IIT-Delhi recently compared the members of a family of minerals called rutile oxides, they found a significant difference between metals and insulators that a well-known mathematical model could not explain. Understanding why is a necessary precursor to design next-generation electronics and efficient industrial catalysts.

While rutile oxides have the same crystal structure, titanium dioxide is an insulator whereas ruthenium dioxide is a good conductor.

The study itself was driven by a long-standing debate over whether ruthenium dioxide possesses a rare, unconventional type of magnetism called altermagnetism. To settle this, the team looked closely at the interplay between the material’s electrons and the lattice, i.e. the grid of its atoms.

Like photons carry light, phonons carry vibrations through a material. By studying how heat affects the phonons of the lattice, scientists can work backwards to see what the electrons are doing. If the electrons were interacting strongly with the phonons, it would leave a specific sign in the data.

The team used a technique called Raman scattering. They shone a laser at the materials and measured how the light changed as it bounced off the vibrating atoms. They simultaneously cooled the samples from room temperature down to –262.15° C.

“All measurements were performed using an indigenously developed low-temperature Raman scattering facility at IIT-Delhi, built at roughly one-third the cost of comparable commercial systems,” IIT-Delhi assistant professor and study co-author Kaushik Sen said.

As they cool, the lattice of most materials becomes stiffer and the vibrations speed up. In insulators, this stiffening follows a well-known mathematical rule called the Klemens model. However, the researchers found that the lattice of the metallic rutile oxides stiffened more and the Klemens