Researchers at Rutgers University in the US have found a new quantum state where matter can exist.
Dubbed quantum liquid crystal, this new state of matter was found when two exotic materials, Weyl semimetal and spin ice, known for their own unique and complex properties, were subjected to high magnetic fields, a university press release said.
We all know the usual states in which matter exists: solid, liquid, and gas. The discovery of the plasma state has opened up new applications in the semiconductor industry and for sterilizing medical equipment while heralding new industries such as nuclear fusion.
Following the discovery of plasma, researchers have focused on extreme ultra-low temperatures or high pressures and magnetic fields to newer states of matter, where materials behave strangely and unexpectedly.
The research approach used by Rutgers scientists could help our understanding of newer states of matter and even accelerate their discovery, the press release added.
Exotic materials used
The researchers used Weyl semimetals and spin ice in their discovery of the new state of matter. Both these materials are considered exotic since they showcase unique and complex properties.
Weyl semimetals allow electricity to flow very quickly and with zero energy loss. This occurs due to quasiparticles called Weyl fermions in them, which allow electricity to flow in this unusual way.
The other exotic material used, spin ice, is highly magnetic, where tiny magnetic fields within the material resemble the position of hydrogen atoms in ice.
“Although each material has been extensively studied, its interaction at this boundary has remained entirely unexplored,” explained Tsung-Chi Wu, a doctoral student at Rutgers, who was involved in the work.
The researchers combined these two materials at extremely high magnetic fields and found a new state of matter, which they refer to as quantum liquid crystal.
“We observed new quantum phases that emerge only when these two materials interact. This creates a new quantum topological state of matter at high magnetic fields,” Wu added in the press release.
Properties of quantum liquid crystal
The researchers found that in this new state of matter, the electronic properties of Weyl semimetal were influenced by the magnetic properties of spin ice. This leads to electronic anisotropy – a rare phenomenon where a material conducts electricity differently in different directions.
The team found that within the 360 degrees of a circle, the material conductivity was the lowest in six specific directions. Interestingly, when the magnetic field was increased, the electrons started flowing in opposite directions. This is similar to a rotational symmetry breaking, a phenomenon seen in quantum states that is used to identify the occurrence of new quantum states under high magnetic fields.
While much of the experimental work needed to achieve this was carried out at the National High Magnetic Field Laboratory (MagLab) in Tallahassee, the researchers also needed a lot of theoretical inputs provided by Jedediah Pixley, associate professor at the Department of Physics and Astronomy at the university.
“It took us more than two years to understand the experimental results. The credit goes to the state-of-the-art theoretical modeling and calculations done by the Pixley group,” said Wu in the press release.
“This is just the beginning. There are multiple possibilities for exploring new quantum materials and their interactions when combined into a heterostructure. We hope our work will also inspire the physics community to explore these exciting new frontiers,” concluded Wu.
The research findings were published in the journal Science Advances.