Tuning order from disordered ground states in geometrically frustrated classical "non-hbar" materials

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Physics and Astronomy

Abstract

Condensed matter physics has developed a relatively complete theory of common phases in materials leading to many technologically important devices including electronic screens, memory storage, and switching devices. Landau, or mean-field theory, has provided a framework to model, predict, and understand phases and transitions in a surprisingly diverse variety of materials and also dynamical systems. While these conventional ground states have proven technologically important and the underlying theory represents a major success for scientists, these phases have proven incredibly difficult to suppress and often emerge when new materials properties are sought or engineered.

To discover novel phases that will lead to a new materials revolution, these common phases need to be suppressed to allow exotic and unconventional properties to emerge. The most common vehicle to turn off conventional phases in materials has been through the introduction of disorder through chemical doping resulting in strong random fields. Many important theories have been formulated and tested to describe the effects of random fields and in particular to account for the fine balance between surface and bulk free energy. However, the use of disorder has proved limiting as properties are often templated into the material and not directly controllable and also the resulting ground state of the material is difficult to understand.

Another route, which has more recently been explored in the last decade, to suppress conventional phases is by introducing strong fluctuations. While this can be trivially done with temperature, new phases have emerged by studying quantum systems where the physics are governed by quantum mechanics and the Heisenberg uncertainty principle. The study of quantum systems has resulted in the discovery of many new phases of matter including high temperature superconductors and also quantum spin-liquids where the magnetism is dynamic at any temperature.

A limitation of quantum fluctuations is that the properties do not carry over directly to ferroelectric based systems and also multiferroics where magnetic and structural properties are strongly coupled. Also, owing to the strong fluctuating nature of the ground state, the properties have not been found to be easily tunable limiting immediate use for applications. This proposal aims to therefore take a different route by studying classically frustrated systems where a large ground state degeneracy is introduced naturally through the lattice and quantum mechanical effects are small. Emphasis will be placed on lattices based upon a triangular geometry. The lack of strong fluctuations (that exists in quantum systems) provides the ability to controllably tune between different ground states making this route a potential means of creating new switching devices or novel memory storage systems.

The proposal aims to investigate classically frustrated magnets and ferroelectrics. These systems can be described within a common framework and will be studied using scattering techniques to provide a bulk real space image of the ground state. The properties will be tuned with magnetic and electric fields supplying a direct route for discovering a new route towards technologically applicable materials. The combined approach of investigating ferroelectrics and magnets will result in a complete understanding applicable to immediate industrial applications. These new materials will lead to the discovery of new phases including new high temperature multiferroics, classical spin liquids, or localized controllable boundaries or defects.

Planned Impact

Impact will be achieved through 1) publication and communication; 2) outreach; 3) making contact with industry; 4) training highly qualified people.

1) The results of the science proposed here will be published in highly cited journals and advertised at international conferences. Manuscripts will also be posted on the publicly available "cond-mat" website based at Cornell University. The PI has an established track record of doing this with over 55 publications posted on this site.

The proposal requests funds for the PI and PDRA to attend international and UK based conferences such as the APS March meeting also the BCA meeting. This is important for advertising the work and maximizing academic impact. The requested travel time to large scale facilities will also allow more informal means of communications including meetings and seminars at host institutions.

2) Part of the proposal will include involving undergraduate students in projects based on the science proposed here. Specifically, this will include hosting 2-3 undergraduates in a real neutron/x-ray experiment every year during innovative learning week (ILW) in the winter semester. Also, undergraduate students will be directly involved with larger projects through the masters and specialist physics routes. Offering these projects will introduce undergraduate students to large scale facility science and allow them to develop skills in the area of computing, materials preparation in the lab, and also project management through organizing a large scale facility experiment. Such skills are important regardless of the career path chosen by the student.

In terms of graduate outreach, a ~6 hour neutron scattering lecture series will be given through the SUPA framework every year as part of the "Probes for Condensed Matter" course offered by the DTC. It is through these efforts that large scale facilities will be advertised and also students introduced to the science involved with this type of research.

CSEC also hosts public outreach events which the PI will remain actively involved in. These events include Erskine Williamson day and also open days at Edinburgh and are aimed at high school students and the general public.

3) Contact will be maintained with the industrial representative at the School of Physics as well as the knowledge transfer officer at CSEC. This will aid in exploiting links with industry that can be made throughout the project. Through the use of speciality equipment manufactured by UK based companies (such as Oxford Instruments) feedback will be provided through groups at large scale facilities to further develop new instruments. Intellectual property will be protected through contact with Edinburgh's knowledge transfer office and ERI (Edinburgh Research and Innovation).

4) The project will involve a graduate student funded through the DTA allocation at the University of Edinburgh and will also involve undergraduate students through masters and senior undergraduate projects. Through the highlighted international collaborations facilitated by this proposal the PDRA and students will learn new skills in materials preparation unique to Edinburgh. The proposal requests funds to travel to unique equipment at NIST (particularly the MACS instrument at the NIST Center for Neutron Research) in Maryland and also for the use of unique sample environments at PSI - Switzerland. It is anticipated that these experiments will be combined with visits to labs based in the University of Maryland and also Rutgers in New Jersey to gain knowledge of new crystal growth techniques. Both universities are within driving distance of NIST. The proposal also requests funds for a PDRA which will aid in launching an independent research career based upon UK based large scale facilities. These combined efforts will help in training individuals to make significant contributions to the UK economy and research.

Publications

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Abdul-Jabbar G (2015) Modulated magnetism in PrPtAl in Nature Physics

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Brown KL (2018) Depth dependant element analysis of PbMgNbO using muonic x-rays. in Journal of physics. Condensed matter : an Institute of Physics journal

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Decaroli C (2015) (C4H12N2)[CoCl4]: tetrahedrally coordinated Co2+ without the orbital degeneracy. in Acta crystallographica Section B, Structural science, crystal engineering and materials

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Gehring Peter (2015) Fluctuating defects in the incipient relaxor K1 -xLixTaO 3 (x = 0 . 02) in APS March Meeting Abstracts

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Gehring PM (2017) Correspondence: Phantom phonon localization in relaxors. in Nature communications

 
Description We have made several discoveries funded by this award:

1) We have observed the breakdown of harmonic magnetic excitations in a metal which is on the verge of superconductivity. This result demonstrates the importance of magnetism and local magnetic excitations in determining the metallic properties of materials. While local magnetism and metallic properties are often considered to be mutually exclusive phenomena, our results demonstrate that they are intertwined.

2) We have directly imaged the molecular motions in a candidate photovoltaic material. This work demonstrates the strong importance that local molecular motions play in determining potentially efficient materials for converting light to usable energy.

3) We discovered a strong coupling between structural and magnetic properties in a new series of magnets. This work demonstrates the importance of orbital physics and also a possible mechanism for developing new materials where structural and magnetic orders are coupled.

4) We have successfully developed flux and Bridgman growth techniques for synthesising single crystals of magneto electric materials. This was a central early goal of the proposal which has been met.

5) Discovered confined and countable magnetic excitations as a result of anti phase boundaries.

6) Discovered a means of using structure to tune excitations.
Exploitation Route 1) Our work on intertwined magnetic and metal properties is being used to probe new theories of superconductivity and creating new ones.

2) The discovery of molecular motions in photovoltaics is being used to develop new materials and also to test theories for new materials.

3) Our discovery of coupling between structural and orbital degrees of freedom has resulted in several collaborations with institutions in the UK and also the United States.

4) Our developed crystal growth labs are being heavily used by groups in Edinburgh and also the subject of visits by groups in Germany and the United States.

5) We plan a new proposal in collaboration with the University of Maryland for tuning magnetism in low dimensional materials.
Sectors Aerospace, Defence and Marine,Creative Economy,Digital/Communication/Information Technologies (including Software),Electronics,Energy

URL http://arxiv.org/find/cond-mat/1/au:+Stock_C/0/1/0/all/0/1
 
Description We have been involved with a new collaboration with Glasgow Engineering and Thales UK. Our work on the low energy fluctuations in ferroelectrics has been applied to developing new sonar devices.
First Year Of Impact 2018
Sector Aerospace, Defence and Marine
Impact Types Economic

 
Description Exploring Electronic Materials with Extreme Conditions
Amount £1,233,585 (GBP)
Funding ID EP/R013004/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 03/2018 
End 12/2022
 
Description STFC Impact Acceleration
Amount £29,995 (GBP)
Organisation Science and Technologies Facilities Council (STFC) 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 12/2016
 
Title New furnace for growth of intermetallic and oxide materials. 
Description A large upgrade/modification for an existing 3-zone furnace was carried out. This will allow new single crystals to be grown for applications to scattering. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact The ability to study new systems. 
 
Title New imaging techniques for magnetism 
Description We have started to work the Scanning Tunnelling group at St. Andrews to image magnetism in low dimensional and metallic compounds. 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? Yes  
Impact This collaboration has resulted in one joint paper and also a new proposal. 
 
Description Applications of polar nanoregions in relaxor ferroelectrics 
Organisation University of Glasgow
Department School of Chemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution Joint project on combining neutron scattering and engineering applications to understand lead based relaxor ferroelectrics.
Collaborator Contribution Materials properties measurements and collaboration.
Impact 1) Joint grant submission planned for June 2017 2) Collaboration for supervising students at Glasgow
Start Year 2016
 
Description Understanding relaxor ferroelectrics for applications 
Organisation Rutgers University
Country United States 
Sector Academic/University 
PI Contribution We have performed neutron and x-ray experiments on samples provided by Rutgers University.
Collaborator Contribution The project partners have provided materials and also access to microscopy for single crystals synthesised at Edinburgh.
Impact We have published two papers on this work and are currently drafting one.
Start Year 2016
 
Description APS March Meeting - 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 1) Established new collaborations with Rutgers University
2) Held meetings with collaborators from NIST and Brookhaven
3) Through the presentation of a talk and also a poster, new projects were established with theorists from University of California and Indiana University.

1) Several finishing graduate students from institutions in Europe and North America expressed interest in applying for the EPSRC funded PDRA position at Edinburgh.
2) Met with editorial staff of several journals to discuss outputs.
Year(s) Of Engagement Activity 2015
 
Description APS March Meeting 2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a talk at the APS March meeting on our work in CaFe2O4. This also involved discussions on future work and experiments.
Year(s) Of Engagement Activity 2018
 
Description APS March Meeting-2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk and meetings regarding scientific collaborations. New collaborations were discussed and established.
Year(s) Of Engagement Activity 2016
 
Description BCA Spring Meeting in York - April 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact 1) New collaborations with theorists from STFC(ISIS) and UCL on langasite compounds.
2) New collaborations (new proposal draft) with groups from Kent University on lattice dynamics in molecular frameworks.
3) Established new collaboration with Queen Mary studying magnon decays in an organic-inorganic framework.

1) Began drafting new project proposal on lattice dynamics in molecular frameworks and finished a paper on this topic.
2) Established future meeting through the CSEC seminar programme on magnon decays in organic-inorganic materials.
Year(s) Of Engagement Activity 2015
 
Description Ferroelectrics-2016 (Invited talk) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave an invited talk on the dynamics of phase transitions in organic-inorganic perovskites. The talk resulted in collaboration with theorists from the Carnegie Institute and also collaboration on high pressure studies.
Year(s) Of Engagement Activity 2016
 
Description Pacifichem Conference (invited talk) - 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave an invited talk on the competition between magnetism and ferroelectricity in PbFe1/2Nb1/2O3. This was based on the work performed at FRM2 and PSI. Discussions/collaboration with theorists was also initiated during this talk.
Year(s) Of Engagement Activity 2015
 
Description Presentation at the Ferroelectrics conference in Vancouver 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A talk was given at a specialized conference on Ferroelectrics.
Year(s) Of Engagement Activity 2018
 
Description Talk at APS March Meeting-2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact An invited talk on the spin fluctuations in the unconventional 115 superconductors was given. Approximately 75-100 people attended the talk. The audience consisted of mostly academics from universities or national laboratories.
Year(s) Of Engagement Activity 2017
 
Description Talk at International Workshop on Ferroelectrics 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact An invited talk was given at the Matsue conference on Ferroelectrics. This workshop also involved meetings with collaborators in China, United States, and Japan. Further projects on Ferroelectrics were discussed and future funding applications will follow.
Year(s) Of Engagement Activity 2016
 
Description Talk/presentation at QENS-2016 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The meeting involved the application of high resolution spectroscopy to study ferroelectrics. These techniques are usually applied to soft matter and biological systems and this meeting evaluated the possibility to apply these to ferroelectrics and other areas of condensed matter physics.
Year(s) Of Engagement Activity 2016