Quasiparticles with mass in one direction found in ZrSiS crystal

For the first time, researchers have identified a quasiparticle that displays massless behavior in one direction while possessing mass in another. This elusive phenomenon, involving particles known as semi-Dirac fermions, was detected within a crystal of zirconium silicon sulfide (ZrSiS), a semi-metal material. The discovery was detailed in the journal Physical Review X and could pave the way for advancements in battery technology, sensors, and other emerging fields, according to scientists at Pennsylvania State University and Columbia University.

The research, led by Dr. Yinming Shao, Assistant Professor of Physics at Penn State, involved using magneto-optical spectroscopy to study ZrSiS crystals. Speaking to Pennsylvania State University, Dr. Shao said that they weren’t specifically searching for semi-Dirac fermions, but the unexpected signatures in their data ultimately led to this first-ever observation. These quasiparticles, first theorised in 2008 and 2009, exhibit unique directional mass behaviour depending on their movement, a concept theorist had labelled the “B2/3 power law.”

Unique Experimental Techniques Used

As per reports, the experiments were conducted at the National High Magnetic Field Laboratory in Florida, using one of the world’s strongest sustained magnetic fields—900,000 times more powerful than Earth’s magnetic field. ZrSiS crystals were cooled to -452°F and exposed to infrared light under this magnetic field. According to reports, the observed energy patterns within the material revealed the distinct behavior of semi-Dirac fermions, which aligned with theoretical predictions from over a decade ago.

Future Potential of ZrSiS

Dr. Shao noted in another statement that ZrSiS is a layered material similar to graphite and may be exfoliated into sheets for precise control, akin to graphene. He explained that understanding these quasiparticles could lead to significant technological breakthroughs. While their discovery solves one mystery, Dr. Shao also emphasised that many aspects remain unexplained, leaving ample scope for further research.