Phonon gated electronics: Changing the electrical transport in molecular devices with vibrations generated via magnetic power absorption
Lead Research Organisation:
University of Leeds
Department Name: Physics and Astronomy
Abstract
The size and speed of electronic appliances have improved exponentially in the last few decades thanks to the advances in materials science and fabrication processes. Nonetheless, these ever smaller and faster components are pushing at the fundamental boundaries of quantum mechanics, which will soon result in excessive heating, defective elements and/or impaired processing. Furthermore, performance limitations are not the only problem for conventional electronics. There is an increasing concern about the environmental and health repercussions for a society that depends on electronics in almost every aspect of our life, with an ever-expanding product range and market base. Many of the materials used in electronic devices are harmful, and the wasteful methods employed for their fabrication, together with the unstoppable updating of electronic gadgets every few years mean that large amounts of hazardous waste is produced.Molecular electronics has the advantages over conventional semiconducting devices of small intrinsic size and potentially biodegradable components. However, the research has so far focused in emulating the operation of standard devices and p-n junctions, rather than developing new functionalities based on the unique properties of molecular structures. Added to metal-molecular contact problems, and the chemical and structural degradation that organic structures undergo during operation, molecular devices still lag the efficiency and durability of conventional structures. Therefore, the electronics industry cannot profit from adopting a new generation of hybrid electronics. This project aims to address these drawbacks by using the intrinsic properties of molecules and molecular dynamics, instead of mimicking semiconductor devices.To bring molecular electronics to fruition as an independent field with intrinsic features, a qualitative conceptual step in hybrid electronics is required. Molecular dynamics, where the atoms vibrate at a characteristic frequency due to the thermal energy, are usually considered a nuisance for molecular devices aiming to emulate semiconducting structures. However, the rich range of vibrational properties in molecules, from low-frequency breathing modes to ultrafast hydrogen bond vibrations, is an attractive possibility to develop new paradigms if we could generate or even artificially control the vibrations at chosen chemical bonds without changing the macroscopic temperature. For this purpose, we can use the power dissipated by magnetic materials during exposure to alternating magnetic fields to generate or quench normal modes in molecules functionalized to, or in contact with the magnet. This power is dependent on an external DC magnetic field, the frequency of the AC magnetic field and the magnetic anisotropy, parameters which can be controlled by external fields or modifying the material composition or shape. This will allow us to study the interaction between electronic transport and molecular dynamics by having control over both voltage andvibrational spectrum.From the point of view of applications to electronic devices, rather than just changing the temperature of the system, the method I put forward will not be hampered by the long relaxation times associated with structural changes in the molecules and the macroscopic cooling of the electrodes. This is because the phonons will be injected directly to the molecules through a third insulating magnetic terminal not in contact with the electrodes. As compared with simply irradiating the molecules with microwave fields, the technique will also allow us to overcome the low microwave absorption of organic molecules, and extend the operation to arbitrary molecular systems, where we will generate vibrational modes in the optical range with exposure to microwave fields. We can then fabricate transistors operating at the molecular scale and with driving magnetic fields at frequencies of several GHz.
Planned Impact
Microelectronics companies such as Intel, Siemens and others have extensive research programmes aiming to push the limits in size and speed of semiconducting devices. Thanks to this research, devices with billions of transistors with nominal size of 45 nm operating at 3 GHz are now widely distributed. However, pushing the limits of the semiconductor technology has given rise to regular faulty operations in many of our state of the art electronic appliances caused by overheating, radiation and/or imperfect nano-components. In addition to performance limitations, the environmental and health effects of large scale production are also urgent issues. Our society discards millions of appliances every year, almost one million tonnes in the year 2000 in the UK, and only about 50 % of those are recycled or exported for re-use, which leads to vast amounts of hazardous waste that includes heavy metals and other poisonous materials. In the local economy, the electronics industry in the UK has been brought to a standstill, with the international trade going from a balance shortfall of 282 million in the year 1995 to 1302 million in 2001, while the total number of companies in the sector fell by 1500, and the computer industry lost 12000 jobs during that period. This proposal offers an answer to some of these problems. So far, research in molecular electronics has been difficult to translate into actual industrial applications, partly due to the fast degradation of molecular devices over short times. Manipulating phonons to gate electronic devices will resolve problems on reproducibility and degradation. By using the same quantum effects that hamper conventional electronics, phonon gating will produce new molecular-size devices operating at clock times faster than 3 GHz. The results will increase the industrial benefits to adopt organic materials for nanoelectronics, making possible a more sustainable process that counterbalances the wasteful lithographic technique through self-assembly and other chemical methods, and relies more in biodegradable materials. It will also trigger a new technology that, to be developed, will require advanced equipment and highly skilled personnel formed in top class institutions, rather than cheap labour. The industry will then profit through investment for technological development and new jobs, whereas the consumers will benefit from faster, smaller and more reliable electronics. To achieve a maximum output from the results of this proposal, we will take action at three levels: i) Regarding the dissemination of our results within the scientific community, we will submit our publications to highly respected journals with high impact factor (e.g. Nature Materials, Nano Letters, etc.). At the local level, we will collaborate with the Microwave Institute and the Centre of Molecular Nanoscience to expand the possibilities of our research. We will contact our past collaborators in Ireland, France and Japan to present them our results so we can explore new possibilities for our method. Finally, we will also present our results in the 56th Conference on Magnetism and Magnetic Materials (November 2011) and the American Physical Society meeting (June 2012), where thousands of scientist gather to communicate their latest achievements. ii) At an industrial level, we will contact electronic companies through the National Microelectronics Institute in the UK and the Enterprise & Knowledge Transfer office of the University of Leeds. Patents and applications will then be discussed with potential industrial partners to maximize the outcome and distribution of the new technology. iii) For the results to reach their full potential rather than being limited to technical publications, it is essential to make them accessible to the wider public. For this purpose, we will contact the appropriate broad diffusion media through the Media Relations office of the University of Leeds and its press officers
Organisations
- University of Leeds (Lead Research Organisation)
- University of Cambridge (Collaboration)
- UNIVERSITY OF GLASGOW (Collaboration)
- Science and Technologies Facilities Council (STFC) (Collaboration)
- Paul Scherrer Institute (Collaboration)
- UNIVERSITY OF YORK (Collaboration)
- CIC nanoGUNE Consolidor (Collaboration)
People |
ORCID iD |
Oscar Cespedes (Principal Investigator) |
Publications
Matamoros-Veloza A
(2018)
A highly reactive precursor in the iron sulfide system.
in Nature communications
Ye S
(2018)
Developing Hollow-Channel Gold Nanoflowers as Trimodal Intracellular Nanoprobes.
in International journal of molecular sciences
Ma'Mari F
(2014)
Direct Measurement of Spin Polarization in Ferromagnetic-C<sub>60</sub> Interfaces Using Point-Contact Andreev Reflection
in IEEE Transactions on Magnetics
Moorsom T
(2014)
Effects of spin doping and spin injection in the luminescence and vibrational spectrum of C60
in Applied Physics Letters
Wheeler M
(2012)
Enhanced Exchange Bias of Spin Valves Fabricated on Fullerene-Based Seed Layers
in IEEE Transactions on Magnetics
Moorsom T
(2014)
Spin-polarized electron transfer in ferromagnet / C 60 interfaces
in Physical Review B
Li S
(2017)
Synchrotron FTIR mapping of mineralization in a microfluidic device.
in Lab on a chip
Description | Measurement of the properties of magnetic thin films (exchange bias, anisotropy, coercivity) grown on top of a C60 film. Proof of principle that phonons and spin currents generated via ferromagnetic resonance can be used to alter the properties of molecular films grown on top of a magnet. The instrument purchased with this grant (Raman microscope) has been used in collaboration with different departments in Leeds (Chemistry, Earth Sciences, Chemical Engineering) and with other institutions (e.g. Universit of Zaragoza in Spain). |
Exploitation Route | In studies of electron and spin transport in hybrid magneto-molecular systems for spintronics, photovoltaics and quantum physics. More recently (2017-2020), the initial results from this grant have lead to novel discoveries, including the dependence between spin pumpin and optical excitations (published in Nature Communications 2017) and the development of a spin capacitor (Science Advances, in press). |
Sectors | Electronics Energy |
Description | To design a new type of device where both spectroscopy and conductivity of a molecular layer are manipulated via microwaves. Use spin currents to operate low-dissipation RF/microwave electronic devices. The instrument purchased with this grant has been used in a number of collaborations with other departments (e.g. Chemistry, Chemical Engineering, Earth Sciences) and institutions (e.g. University of Zaragoza). |
First Year Of Impact | 2012 |
Sector | Electronics |
Impact Types | Cultural Economic |
Description | Multidisciplinary extreme magnetometry: State of the art magnetometry for physical, chemical, biological and engineering applications |
Amount | £182,100 (GBP) |
Funding ID | EP/K00512X/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 11/2012 |
End | 11/2016 |
Title | Simultaneous Raman/photoluminescence-transport measurements |
Description | We have developed an electric transport probe (DC to 26 GHz) in order to perform simultaneous transport-spectroscopy measurements. This is combined with a variable-temperature microstat (3-500 K; only DC) and mapping capabilities for the measurement and characterisation of devices that include characteristic Raman signals (e.g. grapheme, C60, topological insulators) and/or optoelectronic capabilities (photovoltaics, quantum dots, etc.). |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2016 |
Provided To Others? | Yes |
Impact | We have discovered a new type of photovoltaic heterojunction (solar cell) fabricated with C60 and manganese oxide. This combination appears to have polarization-dependent capabilities. We are also collaborating with another group in Leeds to study THz grapheme devices using this capability. |
Description | Collaboration with Hitachi Cambridge Labs. |
Organisation | Hitachi Cambridge Laboratory |
Country | United Kingdom |
Sector | Private |
PI Contribution | Partnership to explore the potential applications of the research performed in this grant. |
Start Year | 2013 |
Description | Ferromagnetic resonance |
Organisation | University of Glasgow |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Preparation of samples and data analysis. |
Collaborator Contribution | Ferromagnetic resonance measurements, donation of waveguides and expertise. |
Impact | Paper in preparation. |
Start Year | 2013 |
Description | PSI low energy muon spin spectroscopy in spin photovoltaic devices. |
Organisation | Paul Scherrer Institute |
Department | Laboratory for Muon Spin Spectroscopy |
Country | Switzerland |
Sector | Charity/Non Profit |
PI Contribution | Our team discovered a spin-capacitive and magnetic field dependent photovoltaic effects that gave the framework for beamtime applications leading to three beamtime runs. |
Collaborator Contribution | Our partners (with our team) carried out measurements of low energy muon spin spectroscopy in spin photovoltaic devices; structures that can generate a photocurrent that is dependent of an applied magnetic field. This opens possibilities for e.g. self-powered magnetic sensors and multifunctional devices. |
Impact | This has lead to a recently accepted paper in Science Advances (In press). The collaboration has involved physics departments (Leeds, St. Andrews), the Scientific Computing Department at STFC and PSI. |
Start Year | 2018 |
Description | Polarised neutron reflectivity in magneto-C60 multilayers |
Organisation | CIC nanoGUNE Consolidor |
Country | Spain |
Sector | Public |
PI Contribution | Leeds fabricated and characterised (magnetometry, Xrays, AFM) Co-C60 and CoGd-C60 multilayers grown via sputtering and thermal evaporation. |
Collaborator Contribution | NanoGUNE fabricated and characterised samples via e-gun and thermal evaporation plus contributed to neutron measurements + analysis. Polarised neutron reflectivity was carried out at ISIS. Transmission electron microscopy was performed at the University of York. |
Impact | Papers listed plus others in preparation. |
Start Year | 2012 |
Description | Polarised neutron reflectivity in magneto-C60 multilayers |
Organisation | Science and Technologies Facilities Council (STFC) |
Department | ISIS Neutron and Muon Source |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Leeds fabricated and characterised (magnetometry, Xrays, AFM) Co-C60 and CoGd-C60 multilayers grown via sputtering and thermal evaporation. |
Collaborator Contribution | NanoGUNE fabricated and characterised samples via e-gun and thermal evaporation plus contributed to neutron measurements + analysis. Polarised neutron reflectivity was carried out at ISIS. Transmission electron microscopy was performed at the University of York. |
Impact | Papers listed plus others in preparation. |
Start Year | 2012 |
Description | Polarised neutron reflectivity in magneto-C60 multilayers |
Organisation | University of York |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Leeds fabricated and characterised (magnetometry, Xrays, AFM) Co-C60 and CoGd-C60 multilayers grown via sputtering and thermal evaporation. |
Collaborator Contribution | NanoGUNE fabricated and characterised samples via e-gun and thermal evaporation plus contributed to neutron measurements + analysis. Polarised neutron reflectivity was carried out at ISIS. Transmission electron microscopy was performed at the University of York. |
Impact | Papers listed plus others in preparation. |
Start Year | 2012 |
Title | Low temperature Raman microscope |
Description | New facility (unique in Leeds) to do Raman microscopy, electron transport and mapping over a broad range of temperatures (3.5-500 K). |
Type Of Technology | New/Improved Technique/Technology |