DCCM · Dynamically controlling the properties of complex materials with light
FP7 — People (Marie Curie Actions)
- Duration
- 2013-08-01 → 2017-07-31
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-CIG
Lines connect the coordinator with its partners.
Results in brief
Dynamically controlling the properties of complex materials with light
The aim of DCCM was to use light to control the electronic and magnetic properties of materials on nanometer length-scales. The project has been very successful and has demonstrated several new techniques and made significant discoveries that will have a lasting impact on the field. We have shown the mechanisms behind the light induced control of the metal-insulator transition in the phase change material Ge2Sb2Te5. We combined time resolved optical spectroscopy and time resolved electron diffraction to measure changes in the electronic and structural properties of the material (Nature Materials 2015). Our results highlighted a new route to controlling the electronic properties of these materials without changing the atomic structure. This enabled us to design a new ultrafast optical modulator (Advanced Materials 2016). We also investigated the role of strain in order to design more energy efficient materials (Nature Communications 2016) and performed detailed measurements on the electronic and thermal properties of these materials close to the transition threshold (Physical Review B 2016). We have used X-ray and THz techniques to investigate the role of phase separation in correlated materials. We showed that domains of electronic order can be controlled by the polarization of a THz field (Nature Communications 2015). Interestingly, we could also show that domain orientation was stable to melt-quench cycles, strongly suggesting that strain also plays a strong role in determining the domain structure (Physica Scripta 2016). We have also applied resonant soft X-ray spectroscopy to image phase coexistence in a correlated material for the first time. We exploited X-ray resonances to metal-insulator phase transitions to measure phase coexistence and domain growth as a function of temperature (arXiv:1612.07998) enabling us to examine the microscopic mechanism for domain growth. These results have enabled us to obtain beam time to examine the dynamics of domain growth at the free electron laser, LCLS, in 2018. We have also made significant progress in understanding how light can control spin dynamics. We have developed a non-linear optical technique to measure spin dynamics. We have used this to show that light can control the antiferromagnetic demagnetization. However, this demagnetization control is indirect. The control comes from the fact that different electronic excited states couple to different structural modes in the crystal, and these modes dictate the demagnetization (Physical Review B 2016). This has important implications for how demagnetization occurs in correlated materials. In addition, our collaboration has performed the world’s first magnetic inelastic X-ray scattering experiment. This enables us to look at spin correlations on nanometer length scales. We found that, while long range spin order could be rapidly and dramatically suppressed, short range spin interactions were robust and were not modified by photoexcitation. More information on these results can be found at http://uods.icfo.eu and the PI, Simon Wall, can be contacted at simon.wall@icfo.eu
Data: CORDIS, © European Union
Project objective
This project will use short pulses of light to understand, manipulate and control the properties of complex materials on nanometre lengthscales and femtosecond timescales. Complex materials have strongly coupled electronic, lattice and magnetic subsystems. This coupling makes the material properties difficult to explain with conventional theoretical techniques, but is responsible for the exotic phenomena that are observed, such as high temperature superconductivity. One method to unravel these interactions is to use ultrafast optical pulses to excite one, typically the electronic, subsystem on a timescale much faster than it couples to other components. This allows the energy flow through the system to be monitored in order to ascertain which parameters are most strongly coupled. In addition, exciting a specific subsystem can also lead to new and interesting properties to emerge. This demonstrates new ways to manipulate, dynamically, the properties of complex materials by light to access new phenomena. However, how these properties emerge still remains largely unknown.My research will address the questions surrounding this issue by attempting to answer, how these properties form and interact from the initial state, how these properties can be manipulated by different excitation mechanism, what properties can be induced and what do they tell us about the properties that define the underlying system? The project will look at both temporal and spatial dynamics to understand how correlations and interactions spread spatially and dynamically through an evolving system. These experiments will require combining a range of microscopic, spectroscopic and femtoscopic techniques in a new and innovative way, ranging from lab based experiments to the use of worldwide user facilities. The research will be fundamental in nature, asking questions that are at heart of condensed matter physics. However, the results will have technological implications that may be exploited.
Original text from CORDIS.
Participants
- FUNDACIO INSTITUT DE CIENCIES FOTONIQUES · CastelldefelsCoordinatorSpain
Links
Data: CORDIS, © European Union