Rutgers Center for Emergent Materials

The Rutgers Center for Emergent Materials supports inter-institutional collaborative research programs on scientifically important and technologically relavent materials among Rutgers University, NJIT and industrial laboratories throughout New Jersey. RCEM also fosters interdisciplinary education for postdoctoral fellows, graduate and undergraduate students as well as high school students.

Latest news

2022

• 8September

  Symposium on Quantum Materials Synthesis (QMS 2022): Materials- vs. Theory-driven Discoveries

  September 8^th - September 10^st, 2022

• The QMS symposium is primarily sponsored by the Gordon and Betty Moore Foundation and will be focused on transformative questions framed around cutting edge challenges for quantum materials synthesis and fabrication. We plan to discuss new synthesis techniques for bulk materials, thin films and heterostructures as well as applications of advanced characterization probes. One of the goals for the symposium is to establish innovative and strongly collaborative network between premier world-wide research institutes, involved in quantum materials research.

  
  

  The main theme of QMS 2022 will be on the question of which one matters most for the discovery of emergent phenomena in quantum materials: new materials synthesis versus theoretical predictions. Are traditional approaches guided primarily by intuitions of synthesis scientists, such as the synthesis of new chemical phases, growth of new crystals or improving materials quality by, for example, controlling defects, still essential for the discovery of new phenomena? or Can new theoretical predictions such as first principles calculations or Hamiltonian approaches really lead to new discoveries?

  
   

  For more information: https://qms2022.physics.rutgers.edu/



 

• 6July

  Topologically protected magnetoelectric switching in a multiferroic

  Nature 599, 576–581 (2021)

• Electric control of magnetism and magnetic control of ferroelectricity can improve the energy efficiency of magnetic memory and data-processing devices1. However, the necessary magnetoelectric switching is hard to achieve, and requires more than just a coupling between the spin and the charge degrees of freedom2,3,4,5. Here we show that an application and subsequent removal of a magnetic field reverses the electric polarization of the multiferroic GdMn2O5, thus requiring two cycles to bring the system back to the original configuration. During this unusual hysteresis loop, four states with different magnetic configurations are visited by the system, with one half of all spins undergoing unidirectional full-circle rotation in increments of about 90 degrees. Therefore, GdMn2O5 acts as a magnetic crankshaft that converts the back-and-forth variations of the magnetic field into a circular spin motion. This peculiar four-state magnetoelectric switching emerges as a topologically protected boundary between different two-state switching regimes. Our findings establish a paradigm of topologically protected switching phenomena in ferroic materials.

  
   

  For more information: onet, L., Artyukhin, S., Kain, T. et al. Topologically protected magnetoelectric switching in a multiferroic. Nature 607, 81–85 (2022). https://doi.org/10.1038/s41586-022-04851-6

 

2021

 

• 24November

  Colossal angular magnetoresistance found in ferrimagnetic nodal-line semiconductors

  Nature 599, 576–581 (2021)

• Efficient magnetic control of electronic conduction is at the heart of spintronic functionality for memory and logic applications1. Magnets with topological band crossings serve as a good material platform for such control, because their topological band degeneracy can be readily tuned by spin configurations, dramatically modulating electronic conduction. Here we propose that the topological nodal-line degeneracy of spin-polarized bands in magnetic semiconductors induces an extremely large angular response of magnetotransport. Taking a layered ferrimagnet, Mn3Si2Te6, and its derived compounds as a model system, we show that the topological band degeneracy, driven by chiral molecular orbital states, is lifted depending on spin orientation, which leads to a metal–insulator transition in the same ferrimagnetic phase. The resulting variation of angular magnetoresistance with rotating magnetization exceeds a trillion per cent per radian, which we call colossal angular magnetoresistance. Our findings demonstrate that magnetic nodal-line semiconductors are a promising platform for realizing extremely sensitive spin- and orbital-dependent functionalities.

  
   

  For more information: Seo, J., De, C., Ha, H. et al. Colossal angular magnetoresistance in ferrimagnetic nodal-line semiconductors. Nature 599, 576–581 (2021). https://doi.org/10.1038/s41586-021-04028-7

 

• 25January

  Kinetically stabilized ferroelectricity in bulk single-crystalline HfO2:Y

  Nature Materials volume 20, pages826–832 (2021)

• HfO2, a simple binary oxide, exhibits ultra-scalable ferroelectricity integrable into silicon technology. This material has a polymorphic nature, with the polar orthorhombic (Pbc21) form in ultrathin films regarded as the plausible cause of ferroelectricity but thought not to be attainable in bulk crystals. Here, using a state-of-the-art laser-diode-heated floating zone technique, we report the Pbc21 phase and ferroelectricity in bulk single-crystalline HfO2:Y as well as the presence of the antipolar Pbca phase at different Y concentrations. Neutron diffraction and atomic imaging demonstrate (anti)polar crystallographic signatures and abundant 90°/180° ferroelectric domains in addition to switchable polarization with negligible wake-up effects. Density-functional-theory calculations indicate that the yttrium doping and rapid cooling are the key factors for stabilization of the desired phase in bulk. Our observations provide insights into the polymorphic nature and phase control of HfO2, remove the upper size limit for ferroelectricity and suggest directions towards next-generation ferroelectric devices.

  
   

  For more information: Xu, X., Huang, FT., Qi, Y. et al. Kinetically stabilized ferroelectricity in bulk single-crystalline HfO2:Y. Nat. Mater. 20, 826–832 (2021). https://doi.org/10.1038/s41563-020-00897-x

 

2020

 

• 4June

  Atomic-Scale Observation of Topological Vortices in the Incommensurate Charge Density Wave of 2H-TaSe2

  Nano Lett. 2020, 20, 7, 4801–4808

• It has been only recently realized that topological vortices associated with structural distortions or ordered spins are rather common in numerous materials where long-range interactions are not dominant. Incommensurate modulations that frequently occur in charge density wave (CDW) materials are often understood in terms of discommensurations with a periodic phase shift. The accumulation of a one-dimensional (1D) phase shift can result in, for example, CDW dislocations in 2H-TaSe2 with incommensurate CDW (I-CDW). Since any atomic-scale experimental investigation of CDW dislocations in 2H-TaSe2 has been lacking, we have performed the atomic-scale observation of 2H-TaSe2 with I-CDW, stabilized with Pd intercalation or strain, with scanning probe microscopy, and unveiled the existence of topological Z6 or Z4 vortices with topologically protected 2D winding movements of atomic displacement vectors. The discovery opens the ubiquitous nature of topological vortex domains and a new avenue to explore new facets of various incommensurate modulations or discommensurations.

  
   

  For more information: https://doi.org/10.1021/acs.nanolett.0c00539

 

2018

 

• 1June

  With support from the Gordon and Betty Moore Foundation and Rutgers University, Center for Quantum Materials Synthesis (cQMS) has been founded and will explore transformative "active wafer" projects by synergistically combining the expertise of single crystal growths of novel materials and those of advanced thin film growths via PLD and MBE techniques.

  
  

  cQMS will accommodate visitors through a visitor program to work on the active wafer projects or ones closely related to the active wafer projects. Proposals are welcome. For more information: http://cqms.rutgers.edu/

  

2016

 

• 3September

  Symposium on Quantum Materials Synthesis (QMS) 2016, Group picture

• 

• 29July

• 

• 24May

  Symposium on Quantum Materials Synthesis 2016: Grand Challenges and Opportunities

  August 30^th - September 1^st, 2016

• It is our pleasure to announce the Symposium on Quantum Materials Synthesis (QMS) (http://qms2016.rutgers.edu), which will take place on August 30-September 1, 2016 in the World Trade Center, Manhattan, New York, USA.

  
  

  The QMS symposium is primarily sponsored by the Gordon and Betty Moore Foundation and will be focused on transformative questions framed around cutting edge challenges for quantum materials synthesis and fabrication. We plan to discuss new synthesis techniques for bulk materials, thin films and heterostructures and application of advanced characterization probes. One of the prime goals for the symposium is to establish innovative and strongly collaborative network between premier research institutions including CIFAR (Canada), EPiQS (USA), IBS (Korea), IOP CAS (China), MPI (Germany), Topo-Q (Japan), and the universities around the world, involved in materials synthesis.

  
  

  The plenary talk will be given by Prof. Shuji Nakamura (Nobel Prize in Physics in 2014) – one of discoverers of blue LED. The QMS symposium will feature 37 invited speakers and a poster session, with anticipated 50 -70 additional registered participants. The participation of early career researchers and Ph.D. students is highly encouraged.

  Among unique aspects of QMS'16 is its strong emphasis on promoting discussions and free exchange of ideas among all of the participants, so we will have three extensive discussion sessions on the topics of: "Materials for room-temperature dissipationless conductors", "Charged Interfaces: the mechanism of charge compensation" and "Topological and other cleavable quantum materials: Bottlenecks and Prospects".

  
  

  We very much hope that you will join us for the exciting gathering by registering for the symposium at http://qms2016.rutgers.edu

  
  

  On behalf of the QMS Symposium Organizing Committee:
  Sang-W. Cheong, Seongshik Oh, and Jak Chakhalian

  
   

  For more information: http://qms2016.rutgers.edu/

 

2014

 

• 12Dec

  Nature Physics Cover Article:

• "Topological defects as relics of emergent continuous symmetry and Higgs condensation of disorder in ferroelectrics"

• 

  It is often said that an open mind can see a universe in a drop of water. In science, a poetic phrase sometimes becomes reality. In our work, we were able to study the laws governing such disparate phenomena as evolution of the early Universe, superfluidity, and exotic superconductivity in a piece of a solid material called manganite. Our samples are ferroelectric, i.e. they exhibit spontaneous electric polarization that might vary from place to place, breaking the samples into domains. The domains can organize into topological entities called vortices (similar to a vortex in a liquid). Such topological entities form in cosmological structures, in particle physics, and in solids. They are governed by a similar "universal" law, and a study of a ferroelectric, for example, can elucidate the characteristics of the early Universe.

  Topological vortices are often elusive and difficult to study (think the early Universe). We have discovered an ingenious and effective way of freezing and subsequently imaging the topological vortices in ferroelectric manganites, and studied the dynamics associated with their formation. We found that it is in close agreement with the well-known Kibble-Zurek mechanism, which was developed to describe topological defects such as monopoles or cosmic strings that influence the evolution of the early Universe.

  Even if a single phenomenon is chosen from the proverbial drop of water, it can be seen differently by different people. A flock of flying geese can be also viewed as a school of fish in an M. C. Escher's artwork. Such "duality" has fascinated people for centuries. In our studies, we constructed such a dual vision of the vortices in our ferroelectric sample, and tested it in experiments. We described the same phenomena using the language of emergence of the ferroelectric order at low temperatures (one description), and also in the language of condensation of the disorder associated with vortices taking over the sample, spanning their entire length, and destroying the order (the dual description). Thus, one event was seen from two entirely different sides - the order and the disorder sides - as also often found in the works of art. Not surprisingly, such a broadened view allows seeing more: the vortices in our samples, exotic superfluids, and even the recently discovered Higgs boson (an elementary particle) can be described in a similar language. Studying one therefore means understanding another. Quite a feat for an unassuming little chunk of solid matter called manganite!

                                                                                                                --Sang-Wook Cheong and Valery Kiryukhin, Rutgers

• For more reading: Ferroelectrics in a twist
  

 

• 12Aug

  Professor Sang-Wook Cheong among "The Most Influential Scientific Minds: 2014"
• Sang Wook-Cheong is listed by Thomson-Reuters as among "The Most Influential Scientific Minds: 2014." This list, which is comprised of 21 field of science and is available at http://highlycited.com/, notes: "Highly Cited Researchers 2014 represents some of world's leading scientific minds ... researchers earned the distinction by writing the greatest numbers of reports officially designated by Essential Science Indicators as Highly Cited Papers - ranking among the top 1% most cited for their subject field and year of publication, earning them the mark of exceptional impact."
• Sang-Wook notes that his former PhD student, Yew San Hor, currently an assistant professor at Missouri University of Science and Technology, is also on the list.

 

• 10Jun

  Story on Color Theorem in Materials for Phys.org (PDF version)
• 

 

• RCEM hosts, at least, one summer high school student through the Partners in Science Program, organized by Liberty Science Center.
• 

 

• 09Apr

  The NSF Designing Materials to Revolutionize and Engineer our Future (DMREF) meeting will be held on Apr. 10-11. (Schedule)

 

• 03Apr

  We announce the start of RCEM Journal Club. Speakers from Physics, Chemistry and Material Science, from both inside and outside of RCEM, will review research papers and various interesting topics in condensed matter physics.

 

• 07Mar

  On APS March Meeting 2014, RCEM members presented 3 invited talks on the studies of vortices of hexagonal manganite and iridium ditelluride.
  1. Z2 x Z3 Symmetry of Multferroic Vortices
  2. Novel phase transitions in iridium dichalcogenides
  3. Topological structural vortex and Kibble-Zurek Mechanism (new title)
      Poster on 28th Annual LSM Symposium-Advances in Nanoscale Materials Imaging (PDF)

 

• 24Feb

  As of Feburary, 2014, there are 157 papers associated with Rutgers Center for Emergent Materials, since 2006 (the year when RCEM was founded), with more than 2600 citations, based on the search results of "Web of Science".
• 

2013

 

• 01Dec

  Professor Weida Wu's group presents the application of a magnetoelectric force microscopy technique that combines magnetic force microscopy with in situ modulating high electric fields. Direct visualization of magnetoelectric domains, Nature Materials 13, 163–167 (2014)
•