Work on 2D Magnets Featured in Nature Physics Journal

University of Maryland Professor Cheng Gong (ECE), along with his postdocs Dr. Ti Xie, Dr. Jierui Liang and collaborators in Georgetown University (Professor Kai Liu group), UC Berkeley (Professor Ziqiang Qiu), University of Tennessee, Knoxville (Professor David Mandrus group) and UMD Physics (Professor Victor M. Yakovenko), have made a new discovery on controlling the magnetic domain behaviors in two-dimensional (2D) quantum magnet, with a paper published in 2025 July issue of Nature Physics. Titled “High-efficiency optical training of itinerant two-dimensional magnets”, the work developed a new approach to using ultralow-power optical incidence to control the size and spin orientations of the formed magnetic domains. Prof. Victor Yakovenko, Dr. Ti Xie, and Prof. Cheng Gong. Photo credit: Shanchuan Liang and Dhanu ChettriProf. Victor Yakovenko, Dr. Ti Xie, and Prof. Cheng Gong. Photo credit: Shanchuan Liang and Dhanu Chettri

Generally, nature likes to evolve towards lower energy for the sake of stability. For example, water flows from mountains down to valleys. However, we often see that water puddles are trapped on the hillside, instead of sliding all the way down to the valleys due to the physical barriers that prevent the stream’s continuous drop. In a nutshell, even though a physical system tends to develop itself into the lowest energy state (i.e., ground state), it can be trapped at many local energy minima (i.e., metastable states). Controlling the kinetic process can guide a system into numerous previously unexplored metastable configurations.

In the recent Nature Physics article, Gong’s team sheds light on 2D magnets to control their magnetic phase transition kinetics, easily weaving a plethora of distinct metastable spin textures onto the atomically thin magnetic flatlands. “The stereotype notion is that a material’s properties are set once its atomic composition and structure are set,” Gong explained, “this is not always the case. The electron spins can arrange themselves in distinct spatial patterns on top of an atomic lattice. Each spin pattern corresponds to the series of associated physical properties magnetically, electrically, optically, and even thermally. This means that one can create numerous quantum materials by magnetic dressing, without the need of changing the material’s compositional skeleton at all."

“The idea is out of the box, yet easily understandable.” Gong further introduced their design, “we implant optically excited spin polarized electrons as tiny magnetic seeds throughout the 2D magnet, by shining a circularly polarized light during the cooling process. When a large-size 2D magnet flake is cooled down across its magnetic phase transition temperature, the electron spins will be aligned to form many domains of either up or down orientation, usually with 50% by 50% populations. However, with the help of magnetic seeds, all the spins nearby can be aligned towards the same orientation following the seeds, resulting in enlarged domain size or even single magnetic domain across the whole material. The orientation of the single magnetic domain can be dictated by the handedness of the circular light”. Their research article includes details on using optical helicity and ultralow optical power density (approximately 20 microwatts per micrometer square) to control the size and orientation of the formed domains. “Well, clearly, this is a non-chemical, reconfigurable method to create artificial quantum materials with arbitrarily designed spin textures, with hopefully on-demand properties,” Gong added.

“The work of the Gong group developed the innovative, non-synthetic method to create artificial quantum magnets by magnetically dressing 2D materials with designed spin textures, potentially reshaping the landscape of quantum materials. This advance is a valuable contribution to the ongoing Quantum Information Science initiatives in the U.S.,” remarked UMD Professor and Quantum Technology Center (QTC) Founding Director Ronald Walsworth.

The novel strategy of optical training of 2D magnets may lead to energy-efficient technology innovations at large. Don Woodbury, Director of Innovation and Partnerships, Clark School of Engineering at University of Maryland, said “The technology developed in the Gong group represent state-of-the-art innovations in 2D spintronic and opto-spintronic devices in ultracompact footprint, with wide implications in integrated nanoelectronics, nanophotonics and magnetoelectric sensors that could find use in both defense and civilian domains.”

Professor Sennur Ulukus, Chair of Department of Electrical and Computer Engineering, University of Maryland, summarized, “The original research led by Professor Gong lies at the intersection of quantum materials and spintronic devices, resonating with the U.S. Quantum Information Science legislation and CHIPS and Science Act. Gong’s sustained high-profile research achievements featured by prestigious journals are successful testimonies of UMD’s quantum and microelectronic workforce.” 

The research work published in this Nature Physics article is primarily supported by the grants from the Air Force Office of Scientific Research under award no. FA9550-22-1-0349 and National Science Foundation under award nos. DMR-2340773, FuSe-2425599, DMR-2326944, ECCS-2429994, DMR-2005108 and ECCS-2429995.

 Original story: https://ece.umd.edu/news/story/discovery-led-by-professor-cheng-gong-featured-in-nature-physics-journal

NASA’s Parker Solar Probe Reveals a Key Particle Accelerator Near the Sun

Flying closer to the sun than any spacecraft before it, NASA’s Parker Solar Probe uncovered a new source of energetic particles near Earth’s star, according to a new study co-authored by University of Maryland researchers. 

Published in The Astrophysical Journal Letters on May 29, 2025, the paper suggests that a process linked to magnetic reconnection—the explosive merging and realigning of magnetic field lines—could propel particles near the sun to extremely high energy. The data sheds light on processes that were impossible to observe in such a harsh environment before Parker launched in 2018, according to study co-author and University of Maryland researcher James Drake.As NASA’s Parker Solar Probe (trajectory shown in green) crossed the heliospheric current sheet, it encountered merging magnetic islands (areas shown in blue) and protons accelerated toward the sun, establishing reconnection as their source. Image credit: JHUAPL. As NASA’s Parker Solar Probe (trajectory shown in green) crossed the heliospheric current sheet, it encountered merging magnetic islands (areas shown in blue) and protons accelerated toward the sun, establishing reconnection as their source. Image credit: JHUAPL.

“We now, for the first time, have a spacecraft that is going through an enormous magnetic reconnection event and can directly measure everything, and that's simply never happened before,” said Drake, a Distinguished University Professor in UMD’s Department of Physics and Institute for Physical Science and Technology (IPST).

Study co-author and Parker Solar Probe project scientist Nour Rawafi, who is also a heliophysicist at the Johns Hopkins Applied Physics Laboratory, added that Parker is enabling researchers to see unexplored regions of the sun.

“Parker Solar Probe was designed to solve some of the sun’s biggest mysteries and uncover hidden processes we couldn’t detect from afar,” Rawafi said, “and this discovery hits right at the heart of that mission.”

Drake and Marc Swisdak, a research scientist in UMD’s Institute for Research in Electronics & Applied Physics (IREAP), were tapped to help analyze Parker Solar Probe data because of their expertise in magnetic reconnection. The two UMD researchers previously identified the mechanism driving the sun’s fast wind and have now interpreted data from a massive magnetic reconnection event measuring four times the size of the sun, according to Drake. 

This data was collected during Parker’s fourteenth swing by the sun in December 2022, when the probe crossed the heliospheric current sheet (HCS), an undulating structure invisible to human eyes. Like a twirling flamenco skirt, the sheet separates regions where the sun’s magnetic field points in opposite directions.

Ripples in the current sheet cause the magnetic fields to merge and rearrange through magnetic reconnection. This releases energy explosively, catapulting a jet of charged particles away as an “exhaust” of energized particles. That same phenomenon affects the Earth-space environment, creating auroral shows at Earth’s poles and geomagnetic storms capable of disrupting satellite communications and causing blackouts.

For nearly four hours in late 2022, Parker passed through the exhaust generated by these reconnection events in the HCS. There, it encountered protons being accelerated, unexpectedly, toward the sun—quashing any doubt over where this energy came from.

“These findings indicate that magnetic reconnection in the HCS is an important source of energetic particles in the near-sun solar wind,” said the study’s lead author Mihir Desai, a solar physicist at the Southwest Research Institute.

Some of the protons that Parker measured had nearly 1,000 times more energy than what could have been transferred by the available magnetic energy. To help pinpoint the mechanism for this surprising energy gain, Drake, Swisdak and IREAP Faculty Assistant Zhiyu Yin (Ph.D. ’24, physics) ran a simulation using a computational model that had been in development for several years at UMD. This study marks the first time their model has been used to directly simulate an observable event. 

“From that simulation, we calculated the spectrum of energetic particles and then compared that with what was seen in the Parker data, and we were able to get a pretty good match,” Drake explained.

Their simulations also confirmed earlier studies, including a 2006 paper co-authored by Drake and Swisdak, which identified “magnetic islands”—loops of the magnetic field that pinch off like water droplets when field lines merge—as the source of this extra energy boost. Particles trapped within the loops get an additional kick as the islands merge and shed their own energy, accelerating some particles nearly to the speed of light. 

“The mechanisms we saw in this study seem consistent with what we have been working on for nearly 20 years, but what surprised me is that these particles gain so much energy,” Drake said. “One important thing about this set of observations is that it demonstrates that magnetic energy can get focused into a small number of extremely energetic particles.”

In addition to demystifying energy exchanges near the sun, learning more about magnetic reconnection—and any resulting solar flares—can help astronauts stay safe.

“These energetic particles are a threat to astronauts if they're out in space,” Drake said. “In a solar flare, you can get some dangerous particles that reach extremely high energies.”

As researchers continue to explore these problems through Parker Solar Probe data, Drake hopes that future observations will chart the spectra of electrons in magnetic reconnection events—a missing piece of the puzzle.

“Our simulations show that the electrons have a lot of energy, but the data we published in this paper don't show the electron spectrum at all,” Drake explained. “One of the important questions is, ‘What carries more energy: the protons or the electrons undergoing acceleration?’ That's one important aspect that we would really like to follow up on.”

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This article was adapted from text provided by the Johns Hopkins Applied Physics Lab and the Southwest Research Institute. 

Their paper, “Magnetic Reconnection–driven Energization of Protons up to ∼400 keV at the Near-Sun Heliospheric Current Sheet,” was published May 29, 2025, in The Astrophysical Journal Letters.

This research was supported by NASA's Parker Solar Probe Mission (Contract No. NNN06AA01C), NASA grants (Nos. 80NSSC20K1815, 80NSSC18K1446, 80NSSC21K0112, 80NSSC20K1255, 80NSSC21K0971 and 80NSSC21K1765), the U.S. National Science Foundation (Grant No. PHY2109083) and Princeton University. This article does not necessarily reflect the views of these organizations.

 

Brenda Dingus Elected to National Academy of Sciences

Visiting Research Scientist and alumna Brenda Dingus (M.S. ’86, Ph.D. ’88, physics) has been elected to the National Academy of Sciences (NAS) for her pioneering work in gamma-ray astrophysics. Brenda Dingus. Image courtesy of Andrew Smith. Brenda Dingus. Image courtesy of Andrew Smith.

Dingus is one of 120 members and 30 international members elected by their peers in 2025, joining a select group of 2,662 scientists around the country recognized for their influential research. She’s one of 26 current UMD faculty members in the National Academy of Sciences and is among 75 named to various esteemed honorary academies.

“This is an incredible honor,” Dingus said. “It is a wonderful recognition of the scientific importance of this new area of astronomy. Gamma-ray astrophysics is a very collaborative and interdisciplinary field, and I want to recognize and thank all the excellent scientists with whom I have had the pleasure to work.”

An astrophysicist who studies the highest-energy light from astrophysical sources, Dingus investigates how nature accelerates particles to extremely high energies, producing gamma rays in space that can be detected from Earth. She is best known for her work in developing innovative gamma-ray detectors and analyzing data to understand cosmic phenomena occurring in extreme environments such as around neutron stars and supermassive black holes.

“Brenda has been a true pioneer in particle astrophysics, with a remarkable breadth and depth of contributions that have profoundly shaped the field,” said Distinguished University Professor of Physics Jordan Goodman, a long-time collaborator who has worked with Dingus on several projects including the Cygnus air shower experiment in 1986. That experiment, conducted at the Los Alamos National Laboratory to study the composition and energy of cosmic rays as they interacted with Earth’s atmosphere, laid the groundwork for future studies in the then-emerging field of cosmic and gamma-ray research.

After earning her Ph.D. from UMD in 1988 under the supervision of Gaurang Yodh, she spent seven years at NASA's Goddard Space Flight Center. She then held tenured faculty positions at the University of Utah and the University of Wisconsin before joining Los Alamos National Laboratory as a staff scientist in 2002. Dingus has been a visiting research scientist at UMD since 2020. 

Throughout her career, Dingus led the development of increasingly sophisticated instruments for detecting gamma rays from space and on Earth. Following her doctoral studies in experimental cosmic-ray physics at UMD, she contributed to the development and implementation of several instruments at NASA Goddard, including the Fermi Gamma-ray Space Telescope and its predecessor, the Energetic Gamma Ray Experiment Telescope (EGRET) on NASA’s Compton Gamma Ray Observatory satellite. Because lower-energy gamma rays cannot be detected on Earth’s surface, EGRET was specifically built to detect and gather data on lower-energy gamma rays in space. The project played a crucial role in mapping the Milky Way and detecting blazars (regions found in the center of galaxies that emit extremely powerful jets of radiation) and continues to influence NASA’s gamma-ray research.

Dingus at the High Altitude Water Cherenkov Observatory in Mexico. Photo courtesy of Jordan Goodman.Dingus at the High Altitude Water Cherenkov Observatory in Mexico. Photo courtesy of Jordan Goodman.Dingus was also an instrumental member of the team responsible for the Milagro experiment, a NASA and U.S. National Science Foundation-funded project that used a water Cherenkov detector placed at high altitude to observe gamma rays from the ground. Milagro’s successor, the High Altitude Water Cherenkov (HAWC) Observatory in Mexico, has identified more than 100 gamma-ray sources since it began operations in 2015, with Dingus serving as U.S. spokesperson, operations manager and principal investigator of the project. HAWC’s notable findings include the first detections of gamma rays exceeding 100 tera-electronvolts (TeV) and “microquasars,” rare binary star systems in which a black hole orbits a normal star. 

An elected Fellow of the American Physical Society and a Los Alamos National Laboratory Fellow, Dingus was awarded a Presidential Early Career Award for Scientists and Engineers in 2000 and an Honorary Medal from the Mexican Physical Society in 2017. Over her 40-year career, Dingus has co-authored 249 publications, which have garnered over 24,000 citations. Dingus also served on numerous advisory committees to the American Physical Society, NASA, the National Science Foundation and the Department of Energy and currently serves on the Board of Trustees of the New Mexico Museum of Natural History and Science.

Dingus continues to work on cosmic- and gamma-ray instrumentation at UMD, collaborating with Goodman and physics research scientist Andrew Smith on the Southern Wide-field Gamma-ray Observatory. Planned for construction in northern Chile in 2026, the observatory will detect air shower particles produced by gamma rays as they interact with Earth’s atmosphere and study extreme astrophysical phenomena, including gamma-ray bursts and supernova remnants. 

Original story by Georgia Jiang: https://cmns.umd.edu/news-events/news/umds-brenda-dingus-elected-national-academy-sciences

Chandra Turpen Cited for Mentorship

Chandra Turpen has been named a University of Maryland Graduate Faculty Mentor of the Year for 2025.

The award recognizes faculty members who have made exceptional contributions to a student’s graduate experience. It both acknowledges outstanding mentoring provided by individual faculty and reminds the university community of the importance of mentoring to graduate studies.Xiechen Zheng, Kellen O'Brien, Stephanie Williams, Chandra Turpen, Yan Li, Patrick Banner and Donna Hammer at the awards ceremony.Xiechen Zheng, Kellen O'Brien, Stephanie Williams, Chandra Turpen, Yan Li, Patrick Banner and Donna Hammer at the awards ceremony.

 “I am consistently amazed at how thoughtful Chandra is as a mentor to her students,” said Physics graduate student Patrick Banner, who organized the nomination. “Whether it's developing our professional skills, advocating for our work to her colleagues, or building up our self-efficacy and confidence in our work, Chandra is a considerate, creative, and careful mentor. Everyone who works with her is so lucky!”

After studying physics and chemistry as an undergraduate at the University of California, Santa Cruz, Turpen earned her Ph.D. in physics at the University of Colorado, Boulder. Following a postdoctoral appointment at Western Michigan University, she joined the University of Maryland in 2011.  She was named an Assistant Research Professor in 2016, and promoted to Associate Research Professor in 2024. Turpen studies the process of learning physics and applies this research to inform the design of curriculum and instruction.  She previously co-chaired a Department of Physics committee devoted to improving the teaching of quantum mechanics. In recent semesters, Turpen has taught PHYS 401 (Quantum Physics 1) and PHYS 371 (Modern Physics). 

Turpen was one of six Graduate Faculty Mentors selected from 33 nominees for this award in 2025.  A campus-wide selection committee of graduate students and past Mentor of the Year Award recipients evaluated the nominations.  

"Dr. Turpen is an incredible mentor, and I am deeply thankful for her guidance throughout my career; she encouraged me to consider graduate school, consistently shares opportunities for growth, and connects me with other scholars,” said Stephanie Williams of the department’s Office of Student and Education Services. “I admire how she shares her own continual growth journey with me, and the ways she has evolved in supporting physics students in the last few years. Anyone would be lucky to know Chandra, and even luckier to have her as a mentor."

The award carries an honorarium of $1,000 to support mentoring activities. Turpen and the other awardees were honored at the Graduate School’s Fellowship and Award Celebration on May 13.