From The College of Engineering At Cornell University Via “phys.org” : “Researchers flip the switch on electric control of crystal symmetry”
From The College of Engineering
At
Via
1.19.23
David Nutt
Atomic-resolution images of the BFO/TSO superlattice. Simultaneous a) HAADF-STEM and b) annular bright-field (ABF-) STEM image of the [(BFO)20/(TSO)10]20//TSO superlattice along the [100]pc zone axis corresponding to Fig. 1f in the main text. Drastic contrast differences in ABF-STEM are observed between the antipolar Pnma-AFE (left) and polar (right) phases. Zoomed in regions for the c) polar and d) anti-polar phases from red and blue boxes in (a), respectively. We note the presence of Bi dumbbells in the polar phase, which is not observed in the ground-state polar R3c phase of BiFeO3. Credit: Nature Materials (2022).
By bringing together the right materials duking it out, a Cornell-led collaboration has for the first time used voltage to turn on and off a material’s crystal symmetry, thereby controlling its electronic, optical and other properties—a discovery that could have a profound impact on building future memory and logic devices.
The group’s paper, “Non-Volatile Electric-Field Control of Inversion Symmetry,” was published Dec. 19, 2022, in Nature Materials [below]. The paper’s co-lead authors are former postdoctoral researcher Yu-Tsun Shao, now a professor at the University of Southern California, and Lucas Caretta of University of California-Berkeley.
The technique is made possible by leveraging the rivalry between the atomic arrangements of two materials: bismuth ferrite and terbium scandate.
“We like to arrange a boxing match between different materials that compete with each other, and at their interface, they’re having a nice struggle,” said co-senior author Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry in Cornell Engineering.
“We make each material just a few atomic layers thick so they can have great influence on each other, and then make slight adjustments to the thicknesses of the layers to make it an even match. When neither layer dominates and suffers significant perturbation from the other material, interesting things can happen. By setting up this frustration, this tug of war or boxing match, the emergent phenomenon turned out to be electrical control of symmetry, which is unheard of, and we’re really excited about it.”
Schlom’s team used molecular-beam epitaxy to create a sandwich of alternating layers of bismuth ferrite—a ferroelectric with the highest polarization of any known material—and terbium scandate, which is not a ferroelectric. Next, Shao and co-senior author David Muller, the Samuel B. Eckert Professor of Engineering, used their lab’s electron microscope pixel array detector (EMPAD)—which is capable of seeing atoms at record resolution—to understand the atomic structure of the sandwich of layers and its polar and nonpolar phases.
“To robustly image this material is quite tricky because systematic artifacts occur when the atoms don’t line up perfectly along a column,” Shao said. “We had to develop a new imaging mode using the EMPAD to decouple the structural information from those errors.”
A group led by co-senior author Ramamoorthy Ramesh at UC Berkeley and The DOE’s Lawrence Berkeley National Laboratory then determined how to electrically switch on and off its inversion symmetry.
Control of such symmetry is an important feature because the behavior of all solid materials is determined by the specific arrangement of their atoms. Inversion symmetry is essentially the characteristic of an object that can be turned inside out without changing its properties, such as a bag or balloon, whereas a left-handed glove that is reversed becomes right-handed and its symmetry is broken.
“Generally, symmetry influences properties. So to be able to control symmetry with an electric field is really powerful,” Schlom said. “It could influence lower-power microelectronics in the area of logic and memory. Because these things don’t forget when you turn off the voltage. It’s nonvolatile. So it wakes up and it knows exactly what state it’s in.”
Bismuth ferrite is usually an insulator, but applying an electric field to the superlattice changes its resistivity by five orders of magnitude, turning it into a semiconductor. The technique also generates changes in the material’s nonlinear optical response of over three orders of magnitude and can “erase” its polarization.
Until now, voltage has almost always broken or removed symmetry. The researchers say it’s unprecedented to find a system that can also turn it on or bring it back.
The team is hopeful the electrical control of symmetry will lead to discoveries in other areas.
“Bismith ferrite is a ferroelectric, and it’s a weak antiferromagnet. So it has both, which is kind of rare in nature already,” Shao said. “Now that we can turn on and off the ferroelectricity, we’re thinking: Can we turn on and off the magnetism as well?”
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The College of Engineering is a division of Cornell University that was founded in 1870 as the Sibley College of Mechanical Engineering and Mechanic Arts. It is one of four private undergraduate colleges at Cornell that are not statutory colleges.
It currently grants bachelors, masters, and doctoral degrees in a variety of engineering and applied science fields, and is the third largest undergraduate college at Cornell by student enrollment. The college offers over 450 engineering courses, and has an annual research budget exceeding US$112 million.
The College of Engineering was founded in 1870 as the Sibley College of Mechanical Engineering and Mechanic Arts. The program was housed in Sibley Hall on what has since become the Arts Quad, both of which are named for Hiram Sibley, the original benefactor whose contributions were used to establish the program. The college took its current name in 1919 when the Sibley College merged with the College of Civil Engineering. It was housed in Sibley, Lincoln, Franklin, Rand, and Morse Halls. In the 1950s the college moved to the southern end of Cornell’s campus.
The college is known for a number of firsts. In 1889, the college took over electrical engineering from the Department of Physics, establishing the first department in the United States in this field. The college awarded the nation’s first doctorates in both electrical engineering and industrial engineering. The Department of Computer Science, established in 1965 jointly under the College of Engineering and the College of Arts and Sciences, is also one of the oldest in the country.
For many years, the college offered a five-year undergraduate degree program. However, in the 1960s, the course was shortened to four years for a B.S. degree with an optional fifth year leading to a masters of engineering degree. From the 1950s to the 1970s, Cornell offered a Master of Nuclear Engineering program, with graduates gaining employment in the nuclear industry. However, after the 1979 accident at Three Mile Island, employment opportunities in that field dimmed and the program was dropped. Cornell continued to operate its on-campus nuclear reactor as a research facility following the close of the program. For most of Cornell’s history, Geology was taught in the College of Arts and Sciences. However, in the 1970s, the department was shifted to the engineering college and Snee Hall was built to house the program. After World War II, the Graduate School of Aerospace Engineering was founded as a separate academic unit, but later merged into the engineering college.
Cornell Engineering is home to many teams that compete in student design competitions and other engineering competitions. Presently, there are teams that compete in the Baja SAE, Automotive X-Prize (see Cornell 100+ MPG Team), UNP Satellite Program, DARPA Grand Challenge, AUVSI Unmanned Aerial Systems and Underwater Vehicle Competition, Formula SAE, RoboCup, Solar Decathlon, Genetically Engineered Machines, and others.
Cornell’s College of Engineering is currently ranked 12th nationally by U.S. News and World Report, making it ranked 1st among engineering schools/programs in the Ivy League. The engineering physics program at Cornell was ranked as being No. 1 by U.S. News and World Report in 2008. Cornell’s operations research and industrial engineering program ranked fourth in nation, along with the master’s program in financial engineering. Cornell’s computer science program ranks among the top five in the world, and it ranks fourth in the quality of graduate education.
The college is a leader in nanotechnology. In a survey done by a nanotechnology magazine Cornell University was ranked as being the best at nanotechnology commercialization, 2nd best in terms of nanotechnology facilities, the 4th best at nanotechnology research and the 10th best at nanotechnology industrial outreach.
Departments and schools
With about 3,000 undergraduates and 1,300 graduate students, the college is the third-largest undergraduate college at Cornell by student enrollment. It is divided into twelve departments and schools:
School of Applied and Engineering Physics
Department of Biological and Environmental Engineering
Meinig School of Biomedical Engineering
Smith School of Chemical and Biomolecular Engineering
School of Civil & Environmental Engineering
Department of Computer Science
Department of Earth & Atmospheric Sciences
School of Electrical and Computer Engineering
Department of Materials Science and Engineering
Sibley School of Mechanical and Aerospace Engineering
School of Operations Research and Information Engineering
Department of Theoretical and Applied Mechanics
Department of Systems Engineering
Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.
Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.
On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.
Cornell University is a private, statutory, Ivy League and land-grant research university in Ithaca, New York. Founded in 1865 by Ezra Cornell and Andrew Dickson White, the university was intended to teach and make contributions in all fields of knowledge—from the classics to the sciences, and from the theoretical to the applied. These ideals, unconventional for the time, are captured in Cornell’s founding principle, a popular 1868 quotation from founder Ezra Cornell: “I would found an institution where any person can find instruction in any study.”
The university is broadly organized into seven undergraduate colleges and seven graduate divisions at its main Ithaca campus, with each college and division defining its specific admission standards and academic programs in near autonomy. The university also administers two satellite medical campuses, one in New York City and one in Education City, Qatar, and Jacobs Technion-Cornell Institute 8in New York City, a graduate program that incorporates technology, business, and creative thinking. The program moved from Google’s Chelsea Building in New York City to its permanent campus on Roosevelt Island in September 2017.
Cornell is one of the few private land-grant universities in the United States. Of its seven undergraduate colleges, three are state-supported statutory or contract colleges through the SUNY – The State University of New York system, including its Agricultural and Human Ecology colleges as well as its Industrial Labor Relations school. Of Cornell’s graduate schools, only the veterinary college is state-supported. As a land grant college, Cornell operates a cooperative extension outreach program in every county of New York and receives annual funding from the State of New York for certain educational missions. The Cornell University Ithaca Campus comprises 745 acres, but is much larger when the Cornell Botanic Gardens (more than 4,300 acres) and the numerous university-owned lands in New York City are considered.
Alumni and affiliates of Cornell have reached many notable and influential positions in politics, media, and science. As of January 2021, 61 Nobel laureates, four Turing Award winners and one Fields Medalist have been affiliated with Cornell. Cornell counts more than 250,000 living alumni, and its former and present faculty and alumni include 34 Marshall Scholars, 33 Rhodes Scholars, 29 Truman Scholars, 7 Gates Scholars, 55 Olympic Medalists, 10 current Fortune 500 CEOs, and 35 billionaire alumni. Since its founding, Cornell has been a co-educational, non-sectarian institution where admission has not been restricted by religion or race. The student body consists of more than 15,000 undergraduate and 9,000 graduate students from all 50 American states and 119 countries.
History
Cornell University was founded on April 27, 1865; the New York State (NYS) Senate authorized the university as the state’s land grant institution. Senator Ezra Cornell offered his farm in Ithaca, New York, as a site and $500,000 of his personal fortune as an initial endowment. Fellow senator and educator Andrew Dickson White agreed to be the first president. During the next three years, White oversaw the construction of the first two buildings and traveled to attract students and faculty. The university was inaugurated on October 7, 1868, and 412 men were enrolled the next day.
Cornell developed as a technologically innovative institution, applying its research to its own campus and to outreach efforts. For example, in 1883 it was one of the first university campuses to use electricity from a water-powered dynamo to light the grounds. Since 1894, Cornell has included colleges that are state funded and fulfill statutory requirements; it has also administered research and extension activities that have been jointly funded by state and federal matching programs.
Cornell has had active alumni since its earliest classes. It was one of the first universities to include alumni-elected representatives on its Board of Trustees. Cornell was also among the Ivies that had heightened student activism during the 1960s related to cultural issues; civil rights; and opposition to the Vietnam War, with protests and occupations resulting in the resignation of Cornell’s president and the restructuring of university governance. Today the university has more than 4,000 courses. Cornell is also known for the Residential Club Fire of 1967, a fire in the Residential Club building that killed eight students and one professor.
Since 2000, Cornell has been expanding its international programs. In 2004, the university opened the Weill Cornell Medical College in Qatar. It has partnerships with institutions in India, Singapore, and the People’s Republic of China. Former president Jeffrey S. Lehman described the university, with its high international profile, a “transnational university”. On March 9, 2004, Cornell and Stanford University laid the cornerstone for a new ‘Bridging the Rift Center’ to be built and jointly operated for education on the Israel–Jordan border.
Research
Cornell, a research university, is ranked fourth in the world in producing the largest number of graduates who go on to pursue PhDs in engineering or the natural sciences at American institutions, and fifth in the world in producing graduates who pursue PhDs at American institutions in any field. Research is a central element of the university’s mission; in 2009 Cornell spent $671 million on science and engineering research and development, the 16th highest in the United States. Cornell is classified among “R1: Doctoral Universities – Very high research activity”.
For the 2016–17 fiscal year, the university spent $984.5 million on research. Federal sources constitute the largest source of research funding, with total federal investment of $438.2 million. The agencies contributing the largest share of that investment are the Department of Health and Human Services and the National Science Foundation, accounting for 49.6% and 24.4% of all federal investment, respectively. Cornell was on the top-ten list of U.S. universities receiving the most patents in 2003, and was one of the nation’s top five institutions in forming start-up companies. In 2004–05, Cornell received 200 invention disclosures; filed 203 U.S. patent applications; completed 77 commercial license agreements; and distributed royalties of more than $4.1 million to Cornell units and inventors.
Since 1962, Cornell has been involved in unmanned missions to Mars. In the 21st century, Cornell had a hand in the Mars Exploration Rover Mission. Cornell’s Steve Squyres, Principal Investigator for the Athena Science Payload, led the selection of the landing zones and requested data collection features for the Spirit and Opportunity rovers. NASA-JPL/Caltech engineers took those requests and designed the rovers to meet them. The rovers, both of which have operated long past their original life expectancies, are responsible for the discoveries that were awarded 2004 Breakthrough of the Year honors by Science. Control of the Mars rovers has shifted between National Aeronautics and Space Administration’s JPL-Caltech and Cornell’s Space Sciences Building.
Further, Cornell researchers discovered the rings around the planet Uranus, and Cornell built and operated the telescope at Arecibo Observatory located in Arecibo, Puerto Rico until 2011, when they transferred the operations to SRI International, the Universities Space Research Association and the Metropolitan University of Puerto Rico [Universidad Metropolitana de Puerto Rico].
The Automotive Crash Injury Research Project was begun in 1952. It pioneered the use of crash testing, originally using corpses rather than dummies. The project discovered that improved door locks; energy-absorbing steering wheels; padded dashboards; and seat belts could prevent an extraordinary percentage of injuries.
In the early 1980s, Cornell deployed the first IBM 3090-400VF and coupled two IBM 3090-600E systems to investigate coarse-grained parallel computing. In 1984, the National Science Foundation began work on establishing five new supercomputer centers, including the Cornell Center for Advanced Computing, to provide high-speed computing resources for research within the United States. As an National Science Foundation center, Cornell deployed the first IBM Scalable Parallel supercomputer.
In the 1990s, Cornell developed scheduling software and deployed the first supercomputer built by Dell. Most recently, Cornell deployed Red Cloud, one of the first cloud computing services designed specifically for research. Today, the center is a partner on the National Science Foundation XSEDE-Extreme Science Engineering Discovery Environment supercomputing program, providing coordination for XSEDE architecture and design, systems reliability testing, and online training using the Cornell Virtual Workshop learning platform.
Cornell scientists have researched the fundamental particles of nature for more than 70 years. Cornell physicists, such as Hans Bethe, contributed not only to the foundations of nuclear physics but also participated in the Manhattan Project. In the 1930s, Cornell built the second cyclotron in the United States. In the 1950s, Cornell physicists became the first to study synchrotron radiation.
During the 1990s, the Cornell Electron Storage Ring, located beneath Alumni Field, was the world’s highest-luminosity electron-positron collider. After building the synchrotron at Cornell, Robert R. Wilson took a leave of absence to become the founding director of DOE’s Fermi National Accelerator Laboratory, which involved designing and building the largest accelerator in the United States.
Cornell’s accelerator and high-energy physics groups are involved in the design of the proposed ILC-International Linear Collider(JP) and plan to participate in its construction and operation. The International Linear Collider(JP), to be completed in the late 2010s, will complement the The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] <a href="http://“>Large Hadron Collider(CH) and shed light on questions such as the identity of dark matter and the existence of extra dimensions.
As part of its research work, Cornell has established several research collaborations with universities around the globe. For example, a partnership with the University of Sussex(UK) (including the Institute of Development Studies at Sussex) allows research and teaching collaboration between the two institutions.
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