Prof. Myriam P. Sarachik, 2005 Laureate for important experiments on electrical conduction and the transition between metals and insulators
For important experiments on electrical conduction and the transition between metals and insulators.
Who she is. Myriam P. Sarachik is a Distinguished Professor of Physics, City College of New York (CUNY), New York, USA. For more than 40 years, Myriam P. Sarachik has been a prominent experimental condensed matter physicist and a leader in the international physics community. After earning a PhD from Columbia University in 1960, she did postdoctoral work at IBM Watson and Bell Laboratories before joining the faculty at the City College of the City University of New York, where she has been teaching since 1964. In 2003 she served as president of the American Physical Society, the third woman president in the society’s 105-year history.
What she does.
Professor Sarachik’s career in experimental condensed matter physics has focused on superconductivity, disordered metallic alloys, metal-insulator transitions, hopping transport in solids, and the properties of molecular nano-magnets. In particular, she has made seminal contributions to Kondo physics, a central theme in condensed matter physics, and the metal-insulator transition (MIT). She has shown that, contrary to conventional wisdom, a true phase transition may occur in two-dimensional systems; her group has also demonstrated quantum mechanical spin dynamics in molecular magnets. In her laboratory, she and her team are currently pursuing the study of condensed matter properties at low temperatures, with particular focus on two areas: molecular nano-magnets and the novel behavior of two-dimensional electron systems.
In addition to her accomplishments as an internationally recognized researcher, Myriam P. Sarachik has a distinguished record as a teacher of undergraduate students, graduate students, and post-doctoral associates. She is the author of 150 articles in professional journals and has given colloquia, talks and seminars in many countries. She has testified before the U.S. Congress and works to promote collaboration between physicists in the U.S. and Africa. She received a 2004 Sloan Public Service Award from the City of New York for “blazing trails as a scientist, researcher, teacher, mentor, and humanitarian” and the 2005 Oliver E. Buckley Prize in Condensed Matter Physics. Professor Sarachik is a member of the U.S. National Academy of Sciences and a fellow of the American Academy of Arts and Sciences.
Context of the Laureate’s research
The conducting behavior of solids
An atom consists of a positively charged nucleus, surrounded by electrons that have a negative charge. In many solid materials the atoms are regularly spaced in three dimensions forming a crystal structure which can be insulating or metallic. In the insulator “phase” the electrons continue to be tied to the nucleus, and the material does not conduct electricity. In metals some of the electrons (those furthest from the nucleus) can move freely throughout the solid: a metallic phase is conducting. Semiconductors are intermediate between the two: pure semiconductors are insulators at very low temperatures, while they become metallic with the addition of controlled amounts of “dopant” substances at higher temperatures. “Doped” semiconductors are the basis for much of our technology. For example, semiconductors are used to make transistor switches, where the presence or absence of a current denotes a “0″ or “1″ in digital electronics and computers.
The Kondo effect before Kondo
Myriam P. Sarachik has studied electrical transport and magnetic properties of a variety of materials, mostly at low temperatures. Some of these materials have potential applications for memory storage and quantum computation. Much of her research has centered around semiconductors, which are the basis of the solid-state optical and electronic devices that have revolutionized communications, computation, and information gathering during the twentieth century. In her own words: “The better we understand their fundamental properties, the better we can utilize them to full capacity.”
Professor Sarachik worked as a Postdoctoral Research Associate at the illustrious Bell Laboratories, where she did a seminal measurement of the resistivity of alloys containing magnetic iron impurities. She found that an unexplained increase in the resistance of the alloy with decreasing temperature was correlated with the presence of the magnetic impurity. The effect was explained shortly thereafter by the legendary Japanese physicist J. Kondo, who cited Myriam Sarachik’s work as the major experimental evidence that the anomaly in the resistivity was associated with magnetic impurities.
Kondo’s calculations showed that electrons of the conducting host metal shield the magnetism in the local vicinity of the magnetic impurity by collectively establishing a “cloud of electrons” with magnetism in the opposite direction. As the temperature is reduced, the shielding becomes more effective and the electron cloud surrounding the impurity presents a bigger obstacle and a larger resistance to current flow. The Kondo effect is now ubiquitous and central in solid state physics and many people think that this discovery and its explanation were worth a Nobel recognition.
A large spectrum of creativity
Myriam P. Sarachik has been interested in the behavior of systems as they transform from one “phase” to another. For example, materials can be in the solid, liquid or gas phase, and the transitions between them are called “phase transitions” (e. g. ice melts to become water, water boils to become steam). Another example is the “metal-insulator” transition between a metallic phase (where a material conducts electricity) and an insulating phase (where it does not). Professor Sarachik has investigated “metal-insulator” transitions in semiconductors, and more recently in two-dimensional layers. It has been believed for many years that a metallic phase cannot exist in two dimensions (in contrast to the three dimensional world we live in). With coworkers, she has shown that there is an apparent transition to a metallic phase, where the electrons are free to move in the plane of the layer. Whether a true metallic phase can exist in two dimensions is currently a matter of great interest that is being hotly debated.
Myriam P. Sarachik has been interested in many subjects and has changed fields of interest many times. She is now also investigating an interesting class of materials called molecular nanomagnets, or “single molecule magnets”. These are insulating solids that contain a very large number of identical molecules that are tiny little magnets regularly arranged on a crystal structure. These materials are fascinating because they display behavior that straddles the classical (macroscopic) world we are all familiar with, and the bizarre world of quantum mechanics which dominates at very small distances. Professor Sarachik’s group demonstrated quantum mechanical flipping of these tiny magnets at low temperatures, a major finding in the field. Molecular magnets are also interesting because of their potential for high density storage of information, a nanomagnet pointing up or down representing a “0″ or “1″; and possibly as an element (or “qubit”) for a quantum computer. Although no one has yet succeeded in implementing it on a useful scale, quantum computation is under investigation as a novel computational paradigm.
Instead of the two states, “1″ and “0″, of classical physics, qubits deal with combinations (or “superpositions”) of “1″ and “0″, thereby taking advantage of the much broader, rich complexity of quantum mechanics. Beyond doubt, Myriam Sarachik has maintained a high level of creativity and open mindedness throughout her life.
Myriam P. Sarachik is an experimental condensed matter physicist with almost 150 published articles to her name. She has been President of the American Physical Society, and is Distinguished Professor of Physics at the City College of the City University of New York, where she has been teaching since 1964.
Born in Antwerp, Belgium, Myriam P. Sarachik was almost 7 when World War II broke out and her family had to flee the country, arriving in Havana in late 1941. They remained in Cuba for five and a half years before emigrating to the United States.
Professor Sarachik leads an active, busy and rewarding life. While her professional life is in physics, she derives pleasure and inspiration from music, the arts, her family, friends and colleagues
Do not look for the enemy behind every tree!
Myriam P. Sarachik knows from her own experience how hard it is to counsel others. What advice would you give to a young woman scientist?“I worry that I might sound like pompous Polonius in ‘Hamlet’, spouting insights that sound wise but are shallow…Nevertheless, I shall try. I would urge women to look for their inner strength, trust in it, to respect themselves and their worth. It is important to choose something you love to do, and to invest yourself in it wholeheartedly. Do not let anything or anyone talk you out of it. But be prepared to work hard. And do not look for the enemy behind every tree: most people are on your side and many will help you accomplish your goals if you give them the chance.”
While conditions for women have changed, in many ways they are quite the same
Myriam P. Sarachik knows from her own experience how hard it is to counsel others. “What advice would you give to a young woman scientist?”
“I worry that I might sound like pompous Polonius in ‘Hamlet’, spouting insights that sound wise but are shallow…Nevertheless, I shall try. I would urge women to look for their inner strength, trust in it, to respect themselves and their worth. It is important to choose something you love to do, and to invest yourself in it wholeheartedly. Do not let anything or anyone talk you out of it. But be prepared to work hard. And do not look for the enemy behind every tree: most people are on your side and many will help you accomplish your goals if you give them the chance.”
While conditions for women have changed, in many ways they are quite the same
“I was one of a handful of women doing graduate work in physics. The (largely male) faculty did not take me seriously, but I was nevertheless expected to measure up to the same standards as the men. Obtaining a position and staying in the field was an enormous challenge.”
“Today many more women earn advanced degrees in the sciences, and they have more opportunities. Still, the numbers are too small, particularly in the physical sciences, and I find this puzzling. Women ‘drop out’ at a substantially greater rate than men, and there are far too few women in high positions.”
“While conditions for women have changed since I was a child, in many ways they’re quite the same – ‘Plus ça change, plus c’est la même chose’: we have made little progress in resolving some of the underlying problems. Married couples continue to have great difficulty obtaining two positions in the same geographical location. Moreover, although men and women now share household chores and childrearing to a greater degree, it is still the woman who generally bears the greater responsibility for the family and the larger share of the work. And child care is an enormous problem. I believe we need more imaginative solutions to these problems.”
Physics looked like something you can sink your teeth into… Like most college students, Myriam P. Sarachik had a tough decision to make when it was time to choose her major. She had to decide between mathematics, music, languages and physics, among other things.
“Physics was very challenging, very highly regarded, and I was very good at mathematics; it looked like something I could sink my teeth into, and it was fun. My father did not have the opportunity to get a formal education. Self-taught, he was an exceptionally well-informed and intelligent man who had enormous respect for intellect and intellectual pursuits. My father admired physics above all other disciplines. My mother had (and still has) very high expectations for her children. So, I was strongly encouraged to pursue my love of literature, music, and mathematics. I read voraciously and I was intrigued and challenged by puzzles, concepts and patterns. However, there was no expectation that I would actually use any of this. My role in life was to marry, to have children, and to raise them (at home). Women worked only out of economic necessity if their husbands were unable to provide for them adequately. So my family did not object to my interest in the sciences. Rather, the issue was my choice to pursue any career at all. I had internalized these assumptions, both overt and tacit, and I had to deal with my own expectations regarding the role of women in society.”
here is great pleasure in stretching the brain. “When doing research, the sudden moments of transparency and insight are quite wonderful. I remember one occasion lying on the grass on a lovely summer evening enjoying an open-air concert in Central Park in the middle of Manhattan. The music and the weather were quite marvelous. Some recent data that I did not understand kept racing back and forth inside my head. And a pattern (in the form of an unexpected, but robust relation between two fundamental parameters) suddenly fell into place. I had no pencil, no paper, I could not be sure! But I checked it mentally again and again. Such moments are truly exhilarating. There is great pleasure (also work and occasional pain) in stretching, stretching, stretching the brain. That result held fast, and appears in one of my publications. I should tell you, however, that other ‘insights’ that came to me, sometimes in the middle of the night, did not survive careful scrutiny. I think that the brain is constantly attempting to resolve the puzzles, often in the background when you’re not aware of it. It’s quite special.”
I have many questions to ask the genie in the bottle. “There are questions that emanate from my own research on which I have spent a great deal of time. I am interested in the behavior of systems as they transform from one ‘phase’ to another. For example, materials can be in solid, liquid or gas phases, and we study the transitions between them (e.g. ice melts to become water, water boils to become steam). Another example is the transition between a metallic phase (where a material conducts electricity) and an insulating phase (where it does not); this is referred to as the ‘metal-insulator’ transition. It has been believed for many years that a metallic phase cannot exist in two dimensions (in contrast to the three-dimensional world we live in). We have been investigating materials in two dimensions that unexpectedly appear to be metallic. I would ask my friend the genie to guide me towards a definitive experiment that would settle whether what we are studying is a metal or not.”