I spent Monday and Tuesday of this week at Rice University in Houston, Texas. The occasion of my visit was a symposium to inaugurate the university’s new Center for Quantum Materials. Besides meeting researchers and learning about their work, I participated in a panel discussion entitled “Quantum Materials—Perspectives and Opportunities.”
My background is in astronomy, not condensed-matter physics. I’m hardly qualified to talk about research opportunities, but having written about topological insulators, iron-based superconductors, the spin Hall effect, and other discoveries in quantum materials, I could offer a perspective: that of someone who has striven to engage the interest of nonspecialists in condensed-matter physics.
If you want to get people excited about condensed-matter physics, you could tout possible technological payoffs. That’s sometimes a good tactic. Albert Fert and Peter Grünberg discovered giant magnetoresistance in 1988. Within a decade, IBM was marketing the first devices based on the effect: disk-drive read-heads. John Bardeen, Walter Brattain, and William Shockley demonstrated the transistor in 1947. Texas Instruments introduced the first commercial transistor just seven years later.
But there are plenty of phenomena in condensed matter whose likely technological applications are remote or even nonexistent. Some, like the fractional quantum Hall effect, take place at impractically low temperatures. Others, like nematic phases in cuprate superconductors, can seem like the patterns adopted by snowflakes: beautiful, fascinating, and otiose.
Astronomers and particle physicists don’t let the impracticality of their science hold them back from sharing the wonder they feel with the general public. Googling “astronomy open day” yields 21 million hits. Fermilab’s video “What is a Higgs boson?” has been viewed 2 million times.
Granted, astronomers and particle physicists have it easy. They can say their science is about the nature of the universe and its ultimate constituents. Galaxies, solar systems, comets are inspiring. And while the Higgs boson and other subatomic particles are unimaginably tiny, the machines that make and detect them are impressively huge.
But condensed matter’s lack of obvious public appeal is a challenge to be overcome, not one to shrink from. When I write about the field, I try to find the human stories behind the research. How, for example, did Jun Akimitsu come to discover magnesium diboride’s superconductivity in 2000 when previous researchers, decades earlier, had overlooked it? Why did Laurens Molenkamp and Shoucheng Zhang look for the quantum spin Hall effect in a material developed by the military for night-vision goggles?
I also try to connect condensed-matter physics to fundamental physics. The quest to perform topological quantum computations in ultracold wafers of gallium arsenide was inspired, in part, by Edward Witten’s discovery of a duality uniting the Jones polynomial, a mathematical invariant that characterizes knots in three dimensions, and a two-dimensional conformal field theory.
A skyrmion lattice reveals itself in a neutron diffraction pattern as a set of six hexagonally distributed spots, as shown on the left. The underlying crystal lattice, being cubic, can’t yield such a pattern. The configuration of spins in the skyrmion lattice is shown on the right. Each skyrmion’s axis extends into the sample and follows the direction of the applied magnetic field, even when the sample’s orientation in the field is changed. (Figure and caption taken from my news story, “Exotic spin textures show up in diverse materials,” which appeared in Physics Today in April 2009.)
Sometimes it’s possible to tell a personal story and make a fundamental connection. For Physics Today‘s April 2009 issue, I wrote about Christian Pfleiderer’s discovery of a hexagonal lattice of magnetic vortices in manganese silicide, a bulk ferromagnet. Mathematically, the vortices resemble the structures that Tony Skyrme devised in 1962 to account for the symmetries and varieties of hadrons. Pfleiderer was looking for those vortices, which he expected to be arrayed with two- or four-fold symmetry. He discovered their three-fold symmetry serendipitously when he positioned his sample at the wrong angle in a neutron beam.
Those fundamental connections and human-interest anecdotes are not rare—because they inspire basic research and characterize the way humans carry out their research. Whatever flavor of physics you do, consider recounting anecdotes and making fundamental connections in your next public talk, school show-and-tell, and congressional visit. You’re already doing those things, right?
