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CMP FAQ

Q1: What is condensed matter physics?

According to Wikipedia, condensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of constituents in a system is extremely large and the interactions between the constituents are strong. To get better idea, here is the description from Condensed-matter and materials physics - Basic research for tomorrowś technology (National Research Council, 1999): 

Condensed matter physics has played a key role in the technological advances that have changed our lives dramatically in the last 50 years. Driven by discoveries in condensed matter and materials physics, these advances have brought us the integrated circuit, magnetic resonance imaging (MRI), low-loss optical fibers, solid-state lasers, light-emitting diodes, magnetic recording disks, and high-performance composite materials. These in turn have led to the spectacular growth of modern computer and telecommunications industries and consequently, to the information revolution.
For many years after the invention of the transistor, the major intellecual challenge facing researchers in condensed matter physics was to understand the physical properties of nearly perfect single crystals of elements, simple compounds, and alloys. Most of these materials occur in some form in nature. On a basis of increased knowledge and powerful new synthesis techniques, today´s condensed matter physics is directed toward creating entirely new classes of materials --- so-called "artificially structured" materials --- that do not exist in nature and whose sizes reach all the way down to the atomic domain. At the same time, a growing number of researchers are using new theoretical and experimental tools to extend our understanding to much more complex forms of matter.... Condensed matter physics is multifaceted and diverse interdisciplinary field, strongly linked to other science and engineering disciplines that both benefit from and contribute to its successes. 

Q2: What are quantum materials and why are they interesting?

Quantum materials are substances that, when subjected to extreme temperatures and other circumstances, produce new and unusual phenomena at the subatomic level. Quantum materials can become endowed with superconductivity, unusual forms of magnetism, strange phase transitions, and other physical qualities that we are only beginning to understand. (From the CIAR Quantum materials site.)

Perhaps the most important lesson learned from studying the physics of systems that contain many particles is that when the number of particles in the system is large enough, entirely new phenomena can appear. These new behaviors of the whole system may not have any obvious relationship to the properties of the individual particles, but rather may arise from collective or cooperative behavior of all the particles. Such phenomena are often referred to as "emergent phenomena" because they emerge as the complexity of a system grows with the addition of more particles. 

This spirit is succintly summarized as "More is different" by Philip Anderson (Nobel prize in physics 1977) in his famous article in 1972. Recently published book, "A Different Universe: Reinventing Physics from the Bottom Down" written by Robert Laughlin (Nobel prize in physics 1998) stresses this emergent aspect of condensed matter physics.

Another important aspect of quantum materials is the strong correlation between electrons. Sometimes they are referred to as "strongly correlated electron systems". One electron theory that most students learn in the elementary solid-state physics courses (based on Kittel, or Ashcroft+Mermin) has been remarkably successful in describing most of simple materials in the last 50 years. However, more complex materials require complete rethinking and new theoretical approaches, since the interactions among electrons cannot be ingored any longer.

For further information about the big challenges facing condensed matter physics, one should read the eleven big questions website at http://frontiers.physics.rutgers.edu/qcrit3_files/bigquestions.html

Q3: Why do I want to spend 5 (or more) years of my life on studying condensed matter physics?

First, you are not alone. Condensed matter physics is by far the largest subdiscipline of physics, and there are enormous range and depth of the field. Since the training in condensed matter physics can be easily adapted to other disciplines, it is an excellent opportunity for the people who wants to pursue interdisciplinary career. As a matter of fact, many materials scientist, biophysicist, electrical engineers began their careers as condensed matter physicsists.

Second, problems in quantum materials are extremely challenging, and therefore intellectually very rewarding. As one can see from the big questions list in Q2, there are many fundamental problems to solve. 

Third, you will have ample opportunities to interact with professors. Thanks to relatively small group size (see Q3), faculty members tend to be more hands-on about the daily research activities and progress.

In addition, quantum materials research in Canada is very collaborative, thanks to CIAR. You will meet, discuss, and collaborate with many distinguished scientists all over Canada and world. Many experiments are conducted at x-ray and neutron sources, or high-magnetic field facilities, which provide additional opportunities for students to learn from experts around the world.

Q4: Should I become an experimentalist or a theorist?

No one can definitely answer this question. However, prior exposure or experience is not the best way to judge this. For example, experimental research can be quite different from your undergraduate lab experience, and the nature of expertise required can quite differ between research groups. You should talk to other graduate students to find out what it is like to be a member of individual research group.

Q5. What is the reputation of condensed matter physics at UofT?

UofT has been a major force in condensed matter physics in Canada, especially in the field of low temperature physics in the 20th century. You can find the brief history about the department and McLennan (yes, the namesake of the building) at http://www.physics.utoronto.ca/physics-at-uoft/history.
Due to recent faculty movements, condensed matter physics group has been almost completely rebuilt in the last 5 years, and as a result, the size of the group is relatively small compared to other major physics departments. However, U of T is internationally recognized as having one of the top research programs in the focused area of quantum materials. Stephen Julian has recently joined us from Cambridge University, and holds a Canada Research Chair (Tier 1). Three additional faculty members (YB Kim, Kee, YJ Kim) hold Tier 2 Canada Research Chairs. Four (Julian, YB Kim, Kee, Wei) are members of the quantum materials program of CIAR. Three (YB Kim, Kee, Paramekanti) have won Sloan Fellowships.

Q6. What are the choices?

Quantum materials research group at U of T has wide range of interests in various topics. Some of them include

  • Novel quantum phases and quantum phase transition
  • High temperature superconductivity
  • Nanostructure and nanomagnetism
  • Electronic structure
  • Heavy fermion compounds
  • Unconventional superconductivity
  • Quantum magnetism

You can find possible PhD research topics in individual group webpages. Please see CMP homepage.

Q7. What can I do with PhD in condensed matter physics?

As mentioned in Q3, PhD in condensed matter physics can be a valuable starting point for successful research career in various disciplines. Most of our graduates go on to do further postdoctoral research in universities, national laboratories. It is relatively easy to get a job in industry, since condensed matter physics is most directly related to industrial applications. For example, electronics, semiconductors, telecommunications, advanced materials, petroleum, and pharmaceutical companies all recruit condensed matter physicists.

Q8. How do I begin?

Come and talk to grad students, postdocs, profs listed in the main research page (or email them). Also coming to condensed matter seminar (Monday noon, and announced on the physics homepage) is a good way to learn about current research and meet people. In addition, there is a journal club run by students and postdocs, for details on this, contact John Hopkinson.

Q9. What courses should I take?

See our recommendations.

Q10. Are there opportunities for doing nanoscience?

Yes, there will be opportunities for studying physics at nanometre scale, which turns out to be both surprising and technologically relevant. For example, John Wei group examines the electronic properties of unconventional superconducting and magnetic materials at nanoscale, where the quantum ordering effects occur coherently without being averaged out over macroscopic distances, and manifest themselves as novel phenomena. They utilize an unique combination of cryomagnetic, nanoprobe and nanofabrication techniques in this investigation. In addition, Y-J Kim group investigates novel quantum magnetism behavior in molecular magnets. Contact individual research groups for details.

Q11. What kind of research facilities are available?

Shared experimental facilites are widely available to all members of condensed matter physics. These include PPMS (Magnetometry, specific heat, resistivity, magnetoresistance up to 14T field), crystal growth facilities (furnaces, image furnace), e-beam lithography, pulsed laser deposition system, x-ray diffractometer, Laue machine, MPMS (SQUID magnetometer), spectroscopic ellipsometer, He liquefier, and student machine shop.