TECHNICAL: The magnetic anisotropy energy (MAE) is among the most important functional properties of magnetic elements. It determines the orientation and stability of the magnetization as well as the mechanisms and the dynamics of the magnetization reversal. A key result of this work will be an improved atomic-scale understanding of the MAE, which can greatly facilitate the engineering of nanostructures with MAE values that exceed those of currently-available materials by over an order of magnitude. The PI will implement his long-standing expertise in methods of synthesizing nanostructures with a precision and structural complexity well beyond the state-of-the-art; from isolated structures, to 2- and 3-dimensional hybrid assemblies. Our fundamental understanding of the MAE will improve significantly from the systematic study of local coordination effects, electronic hybridization with the supporting substrate, and interactions with molecular ligands in network structures. Conditions to achieve extremely large MAE will be identified, which could be useful for engineering the MAE by structural design. Exploring the limit of magnetic storage density at room temperature will be a key objective of this five year program Elements of research efforts include low-temperature scanning tunneling microscopy/spectroscopy on self-assembled magnetic nanostructures, x-ray magnetic dichroism experiments complementary to the local characterization on-campus, and travel to Synchrotron facilities for magnetic circular dichroism measurements.
Results will permit the development of extremely high density magnetic recording media. The work will demonstrate self-assembled patterned media based on magnetic nanoclusters, which, if applied in magnetic recording, would allow for unprecedented bit densities beyond 80 Terabit per square inch. NON-TECHNICAL: The Low Temperature STM lab built by the PI will allow for training of undergraduate and graduate students with state-of-the-art tools in nanoscience. This will build the human infrastructure needed to continue research and development in a rapidly growing field that is seen as one of the most significant areas of research worldwide. The long-term goal is to create at UNL, a center of expertise in the important field of STM methods. The interdisciplinary nature of some aspects in this research program will foster research collaborations with other departments and is particularly conducive to a research climate that is attractive for undergraduate and graduate students. The educational component of this work targets the long-term retention of women in UNL's undergraduate and graduate program in Physics. It is based on the PI's previous experience in efforts to improve avenues of success for women in research environments. The PI will coordinate activities to facilitate networking for women students at the national level, to disseminate their contribution in physics. As a key element of this program the PI will develop and host at UNL, a conference for undergraduate women in physics. A new partnership with leaders at UNL in educational outreach has already brought about funding for the first (pilot) year. It is expected that this program will help attract and retain outstanding women physicists to the department and increase the percentage of women in the undergraduate and graduate program significantly. This proposal is co-funded by Metals and Condensed Matter Physics program in the Division of Materials Research, and Inorganic, Bioinorganic and Organometallic Chemistry (IBO) program in the Chemistry Division.
Intellectual Merit: Designing, building and positioning nanostructures at surfaces and engineering their magnetic and other physical properties is a key challenge in nanotechnology. This award has addressed this challenge by supporting research that has made significant advances in the synthesis of low-dimensional metallic and hybrid nanostructures and established fundamental principles for the manipulation of the electronic and magnetic properties in nanostructures through interface engineering. Synthesis routes towards atomically defined metallic nanowires, surface-supported nanoclusters and their directed ordered growth on nanotemplate surfaces have been significantly advanced. The fundamental interactions that determine the magnetic properties of those structures, with focus on the magnetic anisotropy, have been established. The project has further helped pioneering truly two-dimensional hydrogen-bond-ordered organic ferroelectrics, and contributed to the discovery of hydrogen-bonded organic co-crystals. The results obtained can potentially guide the design and manipulation of metallic and organic structures and metal-organic hybrid structures so that they become suitable for applications in information processing, ultrahigh density data storage and low-dimensional organic electronics. Research funded by this award has directly contributed to 17 publications in peer-reviewed journals, one book chapter and one review article. Among those are publications in high-ranking journals including Advanced Functional Materials, Physical Review Letters, Chemical Communciations, and Journal of Physical Chemistry Letters. Broader Impact: This program has contributed in several ways to student training and education at the University of Nebraska – Lincoln. It has directly supported 2 PhD students who graduated under this award and have both moved on to postdoctoral positions at US National Laboratories. It has provided research opportunities and training to two undergraduate students and one REU student. Students from local high schools made research experiences through this project as well, such as through summer internships or Nanoscience workshops held at UNL. Beyond that, the PI of this project communicated research results in an accessible style to local high school students during our annual NanoDays as well as the NanoCamp of our Nebraska Center for Materials and Nanoscience, to Nebraska High School teachers during UNL’s Astronomy Camp, to the interested public during the Science Cafe at the Red9 Club in downtown Lincoln, and to REU students during the Wednesday at One seminar. A significant outcome of this grant is the Conference for Undergraduate Women in Physical Sciences (WoPhys), which the PI has established for research-active undergraduate women interested in STEM disciplines in 2009 and organized annually since. WoPhyS attracts students from across the U.S., and its attendance has been steadily growing since its pilot year in 2009. In 2013 WoPhyS was attended by 106 participants from 26 different states (including Puerto Rico), Canada (1), and China (5); 84 of the participants were women. WoPhyS has become a highly effective recruitment tool. In 2012, the Department of Physics and Astronomy alone received 12 applications from women for graduate school – a significant increase compared to three applications before WoPhyS. In 2011, over 40% of the fall 2011 incoming graduate class was female, which is a prominent accomplishment in physics where women are traditionally underrepresented. The conference is now continued through support by UNL’s major materials science centers, NSF-MRSEC and the Center for Nanofunctional Materials (CNFM). Another specific education and outreach activity by the PI is the development of a scanning tunneling microscope for classrooms together with faculty and students from regional colleges and high schools. The STM operates on air, and the setup includes the actual scanner, supporting electronics and computer software. It will be used in classrooms to demonstrate how nanostructues can be investigated with scanning probe methods. It is planned that the instrument will also be used to teach nanoscience to the interested public during road shows and open houses. This project has found considerable interest in local schools, and is now continued during a partnership with faculty and students at the Californa State University at San Bernardino during an NSF CREST project.
