Dr. Michel Gingras, Professor at the University of Waterloo since 1999, is a leading theoretical physicist in the area of condensed matter physics and frustrated magnetism. He is a Canada Research Chair and was recently elected a Fellow of Royal Society of Canada for his contributions in the theory of magnetic systems.
As a young physicist, Gingras was drawn to laser physics and optics. He obtained a Master degree in laser physics before he switched to condensed matter physics. The latter field offered Gingras a way to combine his interest in mathematics and theoretical work with experimental activities in the field, and to enter into dialogues and close collaborations with experimental colleagues. He was also drawn to the competitive and collaborative nature of the field.
Gingras’ passion for physics cohabitates with his life-long love for skiing. One of the most important directions of Gingras’ work was kick-started one day by a simple conversation during a ski trip. A couple of years into his early academic career, Gingras was skiing with a friend and colleague, a solid-state chemist named Dr. Steve Bramwell. “We were skiing, said Gingras, and between every single ski run you have to ride the chairlift, so you get plenty of time to talk.” Steve and colleague Mark Harris had discovered something for which they had coined the name “spin ice” and Bramwell had given a talk about it that Gingras had just heard the day before their skiing outing. Gingras recounted the conversation: “I said, ‘Your results are very interesting, but I’m not sure I quite believe the theoretical model you propose.’” Bramwell extended an invitation for the physicist to join his study of spin ice. “He said, ‘Just think about it.’” Years later, the physicist is still thinking about spin ice, though it has been a long and ramified journey.
Spin ice is a magnetic material that has atomic magnetic moments as elementary degrees of freedom that are subject to what are known as frustrated, or competing, interactions. “Lots of my colleagues joke and say I’m trying to improve fridge magnets,” said Gingras. “But of course, magnetism is very important…. There’s a very broad effort in physics to try to understand what happens when you have many degrees of freedom or many particles that interact together — what do they do?” In a world in which physicists seek to understand questions from galaxy formation to protein folding, the question of many-body physics is one that touches all corners of the discipline. What arises from the study of many-body physics is a set of questions about the principles by which large collectivities of particles organize themselves spontaneously. “If there are universal principles behind collective physical phenomena, one ought to be able to expose those studying the simplest platform – the simplest one being magnetism”, explained Gingras.
In the late 1980s, scientists discovered high-temperature superconductivity in a new class of copper-oxide materials. Superconductivity is the ability of a material to conduct electricity without any (Ohmic) electrical resistance, or energy dissipation. It became clear very early on that some form of “avoided” magnetism is involved in these materials, requiring the development of theories where such “avoided” magnetism behaves profoundly quantum mechanically, in contrast with the magnetic systems studied from the 1930s to the late 1980s, which were, for the large majority of them, largely described by semi-classical theories in which quantum effects are “small correction details.” Scientists wondered what happens when magnetism fails to robustly develop at sufficiently low temperature, or is just on the fringes of appearing, but does not. In such cases, some materials decline to become magnets and may, instead, become superconductors.
“We don’t really fully understand magnetic systems where the interactions are frustrated and where quantum mechanics take full control of the physics,” said Gingras. A better understanding of frustrated magnetism could possibly lead to the ability to better guide the synthesis of new materials that superconduct at higher temperatures. “If one had materials that superconduct above or at room temperature, it would be totally revolutionary. It would be a transformative discovery akin to when we moved from the lamp tube to the transistor, perhaps even more!”
Spin ice was discovered in the search for frustrated quantum magnets. It turns out that spin ice compounds are, in fact, not quantum in their behaviour. Yet, they have become a crucial springboard to understand the broader scope of frustrated magnets, classical and quantum — a kind of intermediate step to help bridge classical and quantum frustrated magnetism. According to Gingras, the study of frustrated magnetic systems such as spin ice may allow condensed matter physicists to efficiently understand the principles that govern the behavior of vast classes of condensed matter systems subject to strongly competing interactions between the particles. Meanwhile, the search for a quantum variant of spin ice, or quantum spin ice, continues.
Gingras collaborates with experimentalists in Canada and internationally to rationalize experimental results as well as conceive new experiments to test theoretical ideas. His research group employs a wide variety of analytical methods and computational techniques, including the use of large scale numerical simulations. The challenge comes in connecting the theoretical work with the experimental effort, a labor that is not always straightforward. “In this field of frustrated quantum magnetism, there are no textbooks yet, so we’re trying to develop ideas, methods, and tricks to push forward the understanding of these systems”, said Gingras, “but the challenges provide also great opportunities and bring new ideas”. “Having a wonderful group of students and collaborators at Waterloo and strong collaborative network around the world, said Gingras, provides me with great excitement and satisfaction of contributing to the progress of this very important field of research”.
