Using this method could advance technologies like memory devices and sensors, as well as pave the way to future soft materials that are both smart and flexible. 

Liquid crystals, which are used in liquid crystal display (LCD) screens for TVs and phones,  utilize their molecules to mimic the properties of both liquids and solids, giving them unique properties. While soft materials like liquids, gels and polymers have been widely used for their easy-to-process structures and lightweight properties, they tend to deform easily and often require replacement.

Everyday materials are made of molecules that align themselves in preferred directions. But liquid crystals could become much more useful if their molecules are all facing in one direction – obtaining what is called polar order.  

That can be difficult to do in soft materials, said Xiaoguang Wang, co-author of the study and an assistant professor in chemical and biomolecular engineering at The Ohio State University.

“Soft matter can’t compete with existing solid-state storage in speed, reliability or miniaturization, so the question becomes how might we control its internal structure to make it competitive or comparable to traditional hard materials,” said Wang. 

In searching for a solution, researchers found that they could program the movement of liquid crystals with the help of external forces, such as liquid or electricity. In this study’s case, water droplets were used to determine if scientists could influence the liquid crystal’s interface. 

First, the team etched pillars into a piece of silicon and infused liquid crystals between the spaces. Then a layer of water was introduced on top. 

Similarly to how a magnet’s north and south poles would react to a magnetic field, researchers saw that depending on where the droplet was moved, the molecules would immediately respond by pointing in that direction. By moving the droplet over the liquid crystals a second time, that movement could then be changed and pointed in a new direction, said Wang.

Significantly, the experiment also revealed that liquid crystal molecules could be taught to remember their orientation, opening up new ways for soft materials to exchange information without the need for electronics. “It can memorize the directionality of the information that we write into it, which means that our vector-based system operates like a memory device,” said Wang.

The study was recently published in Nature Physics.

While scientists are still working to incorporate this method into bigger projects, gaining the ability to control the position of liquid crystals’ molecules could lead not only to new functionalities for all sorts of technologies, but also new types of physics, said Ufuoma Kara, lead author of the study and a former graduate research associate at Ohio State.

“By imposing a greater level of polarity within these liquid crystal materials, we can explore new levels of applications,” he said. “Part of that includes expanding the amount of knowledge able to be embedded in their systems.” 

While it’s no easy feat, being able to cultivate materials with such abilities on a larger scale would suggest that the next generation of liquid crystals could one day act as both super-small computer processors and vast, reprogrammable memory storage devices. 

“There’s something very exciting in this discovery, and I think it’s a great foundation to spark some curiosity in young people who want to pursue this type of science,” said Kara.

Other co-authors include Boyuan Chen, Rajdeep Mamtani, Yang Xu, Alan Weible, Eric Boerner and Zhan Yang from Ohio State, as well as Simon Čopar and Uroš Tkalec from the University of Ljubljana, Shucong Li from the Georgia Institute of Technology, Yuxing Yao from the California Institute of Technology, and Robin L. B. Selinger from Kent State University.

This work is supported by the National Science Foundation, the Ohio State Materials Research Seed Grant Program, the Center for Emergent Materials, the Center for Exploration of Novel Complex Materials, and the Institute for Materials Research. 

To measure these tiny high-speed events, known as attoseconds, researchers used a laser to generate intense X-ray flashes that allowed them to map the inner workings of an atom. 

Their findings revealed that when electrons are ejected by X-rays, they interact with another type of particle called the Auger-Meitner electron, causing a secondary pause that’s never been detected before. These results have implications for a wide range of research fields, as learning more about these interactions can reveal novel ideas about complex molecular dynamics, said Lou DiMauro, co-author of the study and a professor of physics at The Ohio State University.

“X-rays are interesting probes of matter,” DiMauro said. “You could use them to take a series of stop-action snapshots of a molecule as it evolves before or during a chemical reaction.” 

The study was recently published in Nature.

While there have been many noteworthy leaps in scientists’ ability to study attosecond delays using ultraviolet light over the past two decades, for years it was a task made all the more challenging due to the scarcity of advanced tools needed to produce them. 

It was so difficult that Pierre Agostini, an emeritus professor of physics at Ohio State, was awarded the 2023 Nobel Prize in Physics for his past work developing techniques to study electron dynamics using pulses of light that lasts for hundreds of attoseconds, a unit of time equivalent to one quintillionth of a second.

It wasn’t until relatively recently that new technologies such as the Linac Coherent Light Source (LCLS), a massive free electron laser device at Stanford University’s SLAC National Accelerator Laboratory, made these pulses much easier to create and visualize in the lab, said DiMauro. 

Using the LCLS, the team studied how electrons inhabit a nitric oxide molecule, focusing on the electron particles that reside near the atom’s oxygen core. They found that there were unexpectedly large delays that ranged up to 700 attoseconds, a pattern that suggests more complicated factors could be at play when determining what causes them, said Alexandra Landsman, a co-author of the study and professor of physics at Ohio State. 

“We looked at what happens when you take out the electron from deep inside an atom, and what surprised me was how complex the dynamics of those deeply bound electrons were,” said Landsman. “This means that behavior is much more complex than scientists thought, and we need better theoretical descriptions to fully describe the light-matter interaction.”

Yet despite more research being needed to further understand the structure of these interactions, uncovering formerly hidden details about them also gives scientists new insights to consider, said DiMauro.

For example, if scientists can get a better grasp on intra-particle behavior, some experts speculate that their discoveries could be vital to breakthroughs for early cancer detection technologies, such as being able to use molecular markers to diagnose blood cancers or detect malignant tumors.

Furthermore, this paper suggests that, combined with theoretical models, researchers could use advances in attosecond science to glimpse matter on some of the smallest scales imaginable, as well as study in greater detail many broader mysteries of the physical universe. 

“I’m looking forward to seeing how we use attosecond pulses to learn more about science, engineering or nature in general,” said DiMauro. “Because what’s described in this paper is an indication of a field that’s really going to blossom.”

This study was supported by the U.S. Department of Energy’s Office of Science and Office of Basic Energy Sciences. James Cryan, senior scientist at Stanford’s SLAC National Accelerator Laboratory and an Ohio State alum, was the lead author of the study. Lisa Ortmann of Ohio State was also a co-author. 

This alarming educational gap may be due in part to a mismatch between the mathematics preparation that many undergraduate students have and the math requirements for STEM students in introductory physics courses, said Geraldin​​e Cochran, an associate professor of physics at The Ohio State University. 

To help solve this issue, Cochran, whose research revolves around improving and expanding access to undergraduate and graduate physics education, was recently awarded a $500,000 grant from the National Science Foundation to lead a project aimed at transforming introductory physics courses to help broaden participation in STEM. 

“Nationally, people are rethinking college admissions processes to support every student, especially at public institutions,” Cochran said. “The models I’m trying to document and evaluate are creating physics courses that are really aimed at supporting all enrolled students, regardless of math preparation.”

Her project, titled “INCLUDES Network Connector: A Network to Facilitate Transforming Introductory Physics Courses to Support All Students,” will seek to create physics courses that reduce course-specific math requirements for students by integrating quantitative literacy, a method that involves interpreting numerical information and applying it to real-world examples to solve scientific problems, and in-context math skills. 

NSF connector awards are typically centered around research that relies on shared visions, leadership, communication and scalability to help drive systemic change in education. 

In this case, Cochran plans to build a national community of instructors and researchers interested in making systemic changes to undergraduate physics education. Because a one-size-fits-all model of teaching doesn’t work well, Cochran’s project will document, evaluate and redesign introductory physics courses of various styles to better fit the needs of students. 

To investigate the efficacy of these material adjustments, project members will conduct a mixed-methods study to compare long-term student success through traditional teaching versus the newly transformed models. This process will include analyzing the next-year performances of those in sophomore and junior courses as well as the success rate for students of various demographics. 

Future probes will also encourage participants to share how their experiences with an altered physics sequence impacted their physics, math and engineering identity and if they have any reflections on the course experience post-graduation. 

The plan builds on work already done at the University of Washington, Rutgers University and Lamar University, whose programs sought to foster policies that support students from all backgrounds at the undergraduate level by allowing students to incorporate their real-world knowledge of physics in traditional assessments and created additional time to be mentored by approachable physics faculty members and advanced undergraduates.

One of the ways the project will seek to do something similar at Ohio State is by incorporating skills from algebra, trigonometry and calculus into the physics class. 

“One of the reasons that so many people are resistant to math is because they don’t understand its usefulness,” said Cochran. “They don’t see it in context, but physics can illuminate the real world and connect problems you want to solve.”

Funding from the award will support the creation of additional physics sequences within three participating universities’ physics departments. At Ohio State, one such physics course with the new curriculum, which will be taught by Cochran, will begin this coming fall. 

Cochran, who has worked with Ohio State’s Thomas Gramila, Lisa Barclay and Mary Leist to better understand students’ current needs, hopes to collaborate with other members of the Ohio State community engaged in similar work. For instance, because many individuals in the class will be majoring in engineering, Cochran will also collaborate with Ohio State’s CARE Office to support the development of students’ engineering identities. 

“Regardless of their math background, all accepted students should have the opportunity to succeed in physics and enjoy themselves while doing it,” Cochran said.   

Spintronic memories, like those used in some high-tech computers and satellites, use magnetic states generated by an electron’s intrinsic angular momentum to store and read information. Depending on its physical motion, an electron’s spin produces a magnetic current. Known as the “spin Hall effect,” this has key applications for magnetic materials across many different fields, ranging from low power electronics to fundamental quantum mechanics. 

More recently, scientists have found that electrons are also capable of generating electricity through a second kind of movement: orbital angular momentum, similar to how Earth revolves around the sun. This is known as the “orbital Hall effect,” said Roland Kawakami, co-author of the study and a professor in physics at The Ohio State University. 

Theorists predicted that by using light transition metals – materials that have weak spin Hall currents – magnetic currents generated by the orbital Hall effect would be easier to spot flowing alongside them. Until now, directly detecting such a thing has been a challenge, but the study, led by Igor Lyalin, a graduate student in physics, and published today in the journal Physical Review Letters, showed a method to observe the effect.

“Over the decades, there’s been a continuous discovery of various Hall effects,‘’ said Kawakami. “But the idea of these orbital currents is really a brand new one. The difficulty is that they are mixed with spin currents in typical heavy metals and it’s difficult to tell them apart.”

Instead, Kawakami’s team demonstrated the orbital Hall effect by reflecting polarized light, in this case, a laser, onto various thin films of the light metal chromium to probe the metal’s atoms for a potential build-up of orbital angular momentum. After nearly a year of painstaking measurements, researchers were able to detect a clear magneto-optical signal which showed that electrons gathered at one end of the film exhibited strong orbital Hall effect characteristics. 

This successful detection could have huge consequences for future spintronics applications, said Kawakami.

“The concept of spintronics has been around for about 25 years or so, and while it’s been really good for various memory applications, now people are trying to go further,” he said. “Now, one of the field’s biggest goals is to reduce the amount of energy consumed because that’s the limiting factor for jacking up performance.”

Lowering the total amount of energy needed for future magnetic materials to operate well could potentially enable lower power consumption, higher speeds and higher reliability, as well as help to extend the technology’s lifespan. Utilizing orbital currents instead of spin currents could possibly save both time and money in the long term, said Kawakami. 

Noting that this research opens up a way to learn more about how these strange physics phenomena arise in other kinds of metals, the researchers say they want to continue delving into the complex connection between spin Hall effects and orbital Hall effects.

Co-authors were Sanaz Alikhah and Peter M. Oppeneer of Uppsala University and Marco Berritta of both Uppsala University and the University of Exeter. This work was supported by the National Science Foundation, the Swedish Research Council, the Swedish National Infrastructure for Computing and the K. and A. Wallenberg Foundation.