Everything in our universe, from the blood coursing through our veins to the gasoline we pump into our cars, are made up of atoms, which encompass protons, neutrons and electrons. Although they form the basic foundation of life, atoms continue to be the center of modern day discoveries, and one of the latest findings was made by a UCSB professor and his team.
Stephen Wilson researches and teaches in the field of materials science as a UCSB professor. Materials science blends chemistry, physics and engineering to better understand metals and minerals. According to Dr. Wilson, some of the questions asked in this interdisciplinary field include “What makes metals good conductors? What makes certain metals hard?”
To answer these questions, scientists must take a hard look at atoms and the movement of electrons. Even a fridge magnet can reveal its atomic secrets if one takes the time to investigate.
Fridge magnets are in a ferromagnetic state, which is when the electrons’ spins (or moments) point in the same direction.
“All the electrons are pointing in the same direction, and they all kind of cooperatively add up to this big north pole, south pole…” said Dr. Wilson.
But electrons are typically not always pointing in the same direction.
“The more common state is when the electrons actually talk to each other and decide they want to point antiparallel to one another,” Dr. Wilson said. “We don’t actually experience that so often…(because) they’re all pointing antiparallel to their neighbors and so their net magnetic field all cancels out.”
These electrons, though, still form a magnetic state.
“But we call it an antiferromagnet,” said Dr. Wilson. “This thing, there’s no magnetic field, and this thing won’t stick to your fridge.”
Ferromagnets and antiferromagnets are known as the classical magnetic states. Electrons of ferromagnets and antiferromagnets are based in rectangular structures, in an order that they have formed after interacting and “talking” with each other. This communication about order takes place more easily among electrons lower under lower temperatures, when electrons do not have to deal with the energy associated with heat.
“What if I can dream up a magnet that actually doesn’t ever order? The moments never decide that they all agree on some pattern to pick. What kind of state would that be and how would we define that state?” asked Dr. Wilson.
This frustration seems to occur when a structure is no longer rectangular but instead triangular. And just like human beings, electrons get energized when faced with frustration: frustrated electrons need lower levels of temperature to find order.
“Magnetic frustration lowers the ordering temperature…” said Dr. Wilson. When ordering temperature is lowered “quantum fluctuations eventually take over and the system can stabilize into a fundamentally disordered quantum spin state.”
