Program Highlights

 

Highlights:

Research and education highlights are brief and digestible summaries of recent significant research results or education activities, chosen for their potential interest to a broad audience.

 

Resent Research and Education Highlights

IRG2 highlight 2017

Hybrid 2D-Ferroelectric Structures for Information Technology

Alexei Gruverman, Alexander Sinitskii, Evgeny Tsymbal, and Chang-Beom Eom
Nebraska MRSEC

Ferroelectric materials possess an electric polarization switchable by an applied electric field. This property is preserved down to the nanometer scale, opening avenues for novel applications in nanoelectronics. Nebraska MRSEC researchers have implemented hybrid electronic devices comprising two-dimensional (2D) materials and ferroelectric thin films of barium titanate (BaTiO3) that exhibit polarization-controlled non-volatile modulation of the electronic properties. Using 2D transition metal dichalcogenides, such as MoS2, the researchers showed that electrical switching of polarization in the hybrid MoS2/BaTiO3 structures leads to a drastic change in resistance, which remains stable in the absence of electric field. These resistive changes can be localized to the nanoscale dimensions, thus opening a pathway towards non-volatile, high-density, energy-efficient memory devices.

Picture: A hybrid MoS2/BaTiO3 ferroelectric tunnel junction showing (a) its nanoscale topography and (b) local polarization switching for different amplitude and duration of the applied voltage pulse.

IRG1 2017

Inducing Magnetism by Proximity

Christian Binek and Peter Dowben
Nebraska MRSEC

Unlike ferromagnets, paramagnetic materials do not possess a spontaneous magnetic polarization. The polarization can be induced, however, by proximity of a magnetic material which has a non-vanishing magnetization on its surface. Nebraska MRSEC researchers have demonstrated that paramagnetic materials, such as platinum and palladium, reveal magnetism when thin films of these materials are deposited on a magnetoelectric chromia. Chromia does not possess bulk magnetization, but it has a robust magnetization on its surface – a distinctive property of the magnetoelectric material. The surface magnetization of chromia induces magnetism in the paramagnetic overlayers, which was detected by the researchers. They observed changes in the polarization of a laser light when it was reflected from the paramagnetic films, indicating the presence of the induced magnetization. This finding opens the door to use paramagnetic overlayers for the detection of the surface magnetization of chromia, which plays a key role in prospective ultra-low power memory and logic devices.

Picture: Detection of induced magnetization in paramagnetic thin film of platinum (Pt) deposited on a surface of chromia (Cr2O3). The polarization of electric field (E) rotates when the linearly polarized light is reflected from the magnetized paramagnetic film.

sciencenight

Science Night Live! : Bringing Science to the Public

Rebecca Lai and Jocelyn Bosley
Nebraska MRSEC

Nebraska MRSEC sponsored and organized Science Night Live!, an evening outreach and public engagement event in Lincoln’s popular downtown Railyard district. This unique event brought together over 50 faculty and student researchers with 250 attendees of all ages, creating opportunities for Nebraska scientists to engage the general public with science in ways that challenged stereotypes about who scientists are, how science is done, and why basic research is valuable. Science Night Live! included hands-on science modules and interactive displays; “soapbox science” and “scientist speed-dating” activities in which attendees interacted directly with scientists; and on-stage performances. Through this popular first-time event, MRSEC has expanded the impact of its existing science communication programs, such as Science Slams, in a public forum. To learn more about Science Night Live!, see this interview with Jocelyn Bosley, MRSEC Assistant Director for Education and Outreach, on Lincoln’s Channel 8 Eyewitness News.

Picture: Attendees converse with scientists from UNL and across the country during a “scientist speed-dating” activity at Science Night Live! in the Lincoln Railyard.

seed project

Artificial Magnetism with a Metamaterial

Christos Argyropoulos
Nebraska MRSEC

Electricity and magnetism form a partnership that has led to tremendous technological advances which shaped today's civilization. The interplay between electricity and magnetism is also known to be responsible for electromagnetic waves, such as the visible light. However, magnetic effects at optical frequencies are rather weak and the magnetic component of light plays a minor role in the interactions between light and nanoscale materials. Nebraska MRSEC researchers have designed an artificial material, which exhibits strong magnetism at optical frequencies. Such a “metamaterial” is composed of cylindrical silicon posts placed over a quartz substrate, as shown in figure. According to the researchers’ modeling, the designed metamaterial demonstrates strong magnetic properties useful for a plethora of technological applications, such as compact sensors, optical filters, and efficient, ultrathin optical nonlinear devices.

Picture: Left: Magnetic metamaterial made of periodic cylindrical silicon (Si) posts placed over a quartz (SiO2) substrate. Right: Circulating electric field distribution inside the silicon posts indicating a magnetic response.

Jobstart

Job Start: Preparing Students for STEM Careers

Rebecca Lai and Jocelyn Bosley
Nebraska MRSEC

Nebraska MRSEC’s Job Start workshop, now in its second year, aims to expose students, postdocs, and other early-career scholars in MRSEC-affiliated disciplines to the diverse career opportunities available to those with advanced STEM degrees. Representatives from industry, entrepreneurs from startup technology companies, and Nebraska MRSEC graduates are invited to share their experiences and perspectives, along with researchers in academia. This year, the Job Start workshop featured an interactive presentation by Carmen Sidbury, former provost of Spelman College and now President and CEO of The Sidbury Group, entitled “Transferrable Skills to Help You Win in the Job Hunt.” David Conrad, former President of UNL’s technology transfer office NUtech Ventures and now Vice President of Research and Development at Streck, Inc., offered a talk entitled “Design and Differentiate Your Life’s Work.” Drs. Sidbury and Conrad provided 38 attendees with specific experiences, skills, and strategies they should cultivate to make themselves exceptional candidates for positions in various sectors.

Figure: Dr. Carmen Sidbury emphasizes the cultivation of transferrable skills at the 2017 Nebraska MRSEC Job Start Workshop.

highlight 2017

Trap Passivation to Enhance Solar Cell Efficiency

Xiao Chen Zeng and Jinsong Huang
Nebraska MRSEC

Halide perovskites are promising materials for using them in solar cells – electrical devices that convert the energy of light into electricity. One of the outstanding problems preventing the technological application of these materials is a large number of charged defects on their surfaces. These defects work as traps for electrons when they are extracted from the material under light illumination, thus reducing light-to-electricity conversion efficiency.

Nebraska MRSEC researchers in collaboration with their colleagues from Peking University in China have demonstrated a new approach to solve this problem. They used a Lewis base – a substance which causes traps for electrons on the surface of a halide perovskite to become chemically passive. The researchers showed that such trap passivation improves significantly electron extraction and leads a 45% light-to-electricity conversion efficiency enhancement of the halide perovskite solar cells.

Picture: A Lewis base multilayer introduced into a halide perovskite solar cell leads to efficient trap passivation and electron extraction, resulting in enhanced light-to-electricity conversion efficiency of the solar cell.

highlight 2017

Nebraska MRSEC Research on Cover Pages

Nebraska Materials Research and Engineering Center (MRSEC) is developing new materials with electronic, magnetic, and transport properties that can be controlled with an applied electric field or with electric polarization. A particular emphasis is made on studies of new ferroic materials and structures aimed at developing the fundamental understanding of their properties and related phenomena important for information processing and storage, energy harvesting, and advanced electronics.

In the last year a significant progress has been made by Nebraska MRSEC researchers in these fields as is evidenced from a number of publications in high profile journals which are selected for cover pages of these journals.

Picture: Cover pages of selected journals highlighting Nebraska MRSEC research.

 

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