Department of Applied Physics and Materials Science - Materials Science

News & Events


Exact Optical Frequencies on Demand


Professor Kerry J. Vahala and colleagues have developed a prototype of a miniature device that synthesizes frequencies on demand with about 1 Hertz accuracy. It combines a frequency comb developed at the National Institute of Standards and Technology (NIST) with a "fine-toothed" frequency comb developed at Caltech. To create the finely spaced comb teeth, the Caltech resonator must be about 100 times larger than the NIST device. Its larger size can potentially make this comb very power hungry. "Too much power in a small space can damage any electronics to which the resonator is connected," Professor Vahala says. "Also, in the future, these synthesizer devices could operate on battery power in smartphone-sized devices where they cannot draw much power." But the Caltech comb can generate specific frequencies with minimal amounts of power. [Caltech story]

Tags: APhMS research highlights Kerry Vahala

Building the Starshot Sail


Professor Harry A. Atwater, Jr. is an advisor to a multi-disciplinary $100-million project aimed at designing a spacecraft that can be launched to planets surrounding other stars and reach them within our lifetime. The Breakthrough Starshot Program has three big technical challenges: The first is to build the so-called photon engine, the laser that's capable of propelling the sail; the second is to design the sail itself; and the third is to design the payload, which will be a tiny spacecraft capable of taking images and spectral data and then beaming them back to the earth. Professor Atwater’s role is to help the program define pathways to making a viable lightsail that's compatible with the other objectives of the whole program. [Caltech story]

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Quantum and non-linear forces yield peculiar thermal expansion in silicon


Most materials expand when heated. At temperatures below room temperature, silicon shows the opposite behavior, shrinking as it is heated. Even at room temperature the normal thermal expansion of silicon is rather small. A team led by Professor Brent Fultz wanted to know why, and found that the unusual property is the result of quantum effects coupled by the nonlinear forces between atoms in silicon. [Read the paper]

Tags: APhMS research highlights Brent Fultz Dennis Kim

Solving Pieces of the Genetic Puzzle


Postdoctoral scholar Nathan Belliveau working in the laboratory of Professor Rob Phillips has applied a method called Sort-Seq to mutate small pieces of noncoding regions in E. coli and determined which regions contain binding sites. Binding sites are the locations where specialized proteins that are involved in transcription—the first step in the process of gene expression—attach to DNA. "Humans have such a wide variety of cells—muscle cells, neurons, photoreceptors, blood cells, to name a few," says Professor Phillips. "They all have the same DNA, so how do they each turn out so differently? The answer lies in the fact that genes can be regulated—turned on or off, dialed up and dialed down—differently in different tissues. Until now, there have been no general principles to help us understand how this regulation was encoded." [Caltech story]

Tags: research highlights Rob Phillips APh postdocs Nathan Belliveau

Material Science Student Joins Inaugural Class of Knight-Hennessy Scholars


Aadith Moorthy, a senior majoring in materials science and computer science, has been named to the inaugural class of Knight-Hennessy Scholars, a graduate-level scholarship program founded by Stanford University. The program aims to develop a community of future global leaders to address complex challenges through collaboration and innovation. Aadith will receive a scholarship providing full tuition, room and board, and a living stipend while he pursues a PhD in materials science. [Caltech story]

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New Process Allows 3-D Printing of Nanoscale Metal Structures


Professor Julia Greer and graduate student Andrey Vyatskikh have created complex nanoscale metal structures using 3-D printing. The process, once scaled up, could be used in a wide variety of applications and opens the door to the creation of a new class of materials with unusual properties that are based on their internal structure. [Caltech story]

Tags: research highlights MedE MCE Julia Greer MatSci Andrey Vyatskikh

Professor Fultz Named TMS Fellow


Brent Fultz, Barbara and Stanley R. Rawn, Jr., Professor of Materials Science and Applied Physics, has been named a 2018 Fellow of the Minerals, Metals, and Materials Society (TMS). Professor Fultz received the award for leadership in establishing the importance of vibrational entropy to the phase stability of alloys and for transformational advances in measurement techniques. This is a pinnacle award for the society and it recognizes outstanding contributions to the practice of metallurgy, materials science, and technology. [List of TMS fellows]

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Professor Bernardi Receives NSF CAREER Award


Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, has been awarded the National Science Foundation's (NSF) Faculty Early Career Development (CAREER) Award for his 5-year project, “First-Principles Electron and Spin Dynamics in Materials with Spin-Orbit Coupling”. The CAREER program is NSF's most prestigious awards for junior faculty members. The level and 5-year duration of the awards are designed to enable awardees to develop careers as outstanding teacher-scholars. Awardees are chosen because they exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organizations. [Caltech story]

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Professors Recognized as Highly Cited Researchers


Professors Harry A. Atwater, Jr., Babak Hassibi, Oskar J. Painter, John Seinfeld, Joel A. Tropp, Kerry J. Vahala, and Paul Wennberg have been named by Clarivate Analytics and Web of Science as 2017 Highly Cited Researchers. Their research ranks among the top 1% most cited works in their fields and they are being recognizes for their dedication and focus to expanding the sphere of human knowledge.  [List of recipients]

Tags: APhMS honors Harry Atwater Paul Wennberg Oskar Painter John Seinfeld Joel Tropp Kerry Vahala Babak Hassibi

The Microscopic Origin of Efficiency Droop in LEDs


Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]

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