Dünne Schichten

Group Activities

Most Recent Highlights

 

Control of Switching Modes and Conductance Quantization in Oxygen Engineered HfOx based Memristive Devices

Control of Switching Modes and Conductance Quantization in Oxygen Engineered HfOx based Memristive Devices – © Foto: Gabi Haindl

S. U. Sharath, S. Vogel, L. Molina-Luna, E. Hildebrandt, C. Wenger, J. Kurian, M. Duerrschnabel, T. Niermann, G. Niu, P. Calka, M. Lehmann, H.-J. Kleebe, T. Schroeder, and L. Alff
Adv. Funct. Mater. 2017, 1700432 (DOI: 10.1002/adfm.201700432)

S. U. Sharath is the first author of a publication on resistive random access memory (RRAM) in the high-impact journal Advanced Functional Materials. This type of non-volatile memory has the potential to replace the well-known Flash technology approaching its physical limits. The paper describes the fundamental role of oxygen vacancies in the switching process in hafnium oxide based memory cells. It also reports the stabilization of quantized conductance states at room temperature. RRAM could play a role in all kind of digital memory, in quantum technology and neuromorphic applications. Funding came from German Research Foundation (DFG), the European Union and BMBF through the project PANACHE.

Lückengestütztes Gedächtnis – TU Darmstadt erweitert Grundlagenwissen zu nicht-flüchtigen Speichern (Homepage TU-Darmstadt)

3rd Functional Oxide Thin Films for Advanced Energy and Information Technology

Two „gladiators“ (Lambert Alff, Darrell Schlom) of oxide electronics visiting the colosseum, Rome‘s ancient amphitheatre used for gladiatorial contests and public spectacles. (Photo by Gennady Logvenov.) – © Gennady Logvenov
Two „gladiators“ (Lambert Alff, Darrell Schlom) of oxide electronics visiting the colosseum, Rome‘s ancient amphitheatre used for gladiatorial contests and public spectacles. (Photo by Gennady Logvenov.)

The conference took place for the third time, after Chicago and Cancun this year in July in the Italian capital Rome. The conference was jointly organized by five researchers working in three continents: Bharat Jalan (University of Minnesota), Nini Pryds (Technical University of Denmark), Milan Radovic (Paul Scherrer Institut), Albert Tarancón (Catalonia Institute of Research in Energy) & Nicola Perry (I2CNER, Kyushu University & MIT). Complex oxide thin films are finding applications in a wide range of energy and information technologies, including electron and ion conductors, photovoltaics, thermoelectrics, dielectrics, and resistive switching. This last topic was the focus of the work presented by Lambert Alff (see also Adv. Funct. Mater. 2017, 1700432 (doi: 10.1002/adfm.201700432)).

ATFT researchers visit EES exhibition in Munich

From left to right: Tobias Vogel, Philipp Kehne, Nico Kaiser
From left to right: Tobias Vogel, Philipp Kehne, Nico Kaiser

Small-scale energy storage devices up to 10 kWh and large scale batteries up to 30 kWh are a growing business due to the increasing amount of renewable electricity and electric mobility. At Europe’s largest exhibition for batteries and energy storage system (EES, June 2017) in Munich, Philipp Kehne, Nico Kaiser and Tobias Vogel gained new insights into the current status of the global market of home batteries, electric mobility and large scale storage of electricity. The direct contact with the global manufactures of battery cells, packs and integrated systems showed that the Li-ion technology is dominating the future battery market and companies like TESLA, Samsung and Daimler make large investments. It became obvious, that the increasing demand of critical lithium and cobalt becomes a bottle neck, as batteries have already reached scales from fridges to ship containers. Additionally, no efficient recycling technology was developed by the companies yet, increasing their dependence on raw materials. The exhibition strongly encouraged us that our research on sodium-ion batteries can contribute to the development of cheap batteries, which avoid critical materials and are designed to stay within a circular economy.

ALOVA says Aloha from the IMS 2017

In the scope of the BMBF VIP+ project ALOVA (all-oxide-varactors), Dr. Aldin Radetinac was visiting this year’s IEEE International Microwave Symposium (IMS) held at the Honolulu convention center in Hawaii. The project aims to improve passive microwave components by implementing new highly conducting SrMoO3 oxide bottom electrodes. The symposium was a great opportunity to screen the current state of the art and recent developments in varactor technology as well as to connect to industry.

Philipp² from ATFT at 8th “Lithium Battery Discussions” conference

Left to right: Philipp Kehne, Gennady Cherkashinin, Philipp Komissinskiy
Left to right: Philipp Kehne, Gennady Cherkashinin, Philipp Komissinskiy

“Lithium Battery Discussion” is a focused conference on Lithium ion batteries, with increasing interest in post-lithium technology. The conference initiated detailed discussions by a new format that allowed over one-hour plenary discussion after each topic. With research on novel all-solid-state sodium ion batteries, the ATFT group was represented by Philipp Kehne and Philipp Komissinskiy (Philipp²). We presented new model battery systems, based on solid ß’’-alumina and NaSICON electrolytes, which can be cycled at room temperature under UHV conditions for example in XPS. The team received much interest due to the exceptional cycling performance of these all-soli-state cells, which are a combination of bulk electrolyte and thin film cathode.

Retreat in Grasellenbach

The RESPONSE-team gathered at the spring where, according to legend, Siegfried was killed.
The RESPONSE-team gathered at the spring where, according to legend, Siegfried was killed.

For two days the RESPONSE-team evaluated the on-going activities and discussed new ideas for upcoming research projects in the inspiring atmosphere of Grasellenbach and its legendary hero “Siegfried the Dragonslayer”. In the legend, the murder of Siegfried was avenged by a bloody carnage. More intelligent behavior of leading politicians will hopefully avoid future wars on raw materials.

Doctoral graduation in the ATFM group

We congratulate Dr. Arzhang Mani to his successful PhD defense (16 June 2017). The title of his thesis is: Epitaxial ferrolectric all-oxide varactors for application in reconfigurable RF front ends. With his work he opened up the road towards a large effort project with the goal to validate the innovation potential of this novel type of varactor. Arzhang will be remembered in the group not only for his guitar playing of Persian songs at barbecue parties. Arzhang, good luck for your future career!

Doctoral graduation in the ATFM group

© Foto: Gabi Haindl

It is our pleasure to congratulate Vikas Shabadi to his successful doctorate defense (21 April 2017). His thesis has the title: Epitaxial engineering of ferrimagnetic double perovskites. The defense was followed by a perfectly prepared Indian party with delicious food and drinks. We thank Dr. Shabadi for this memorable day and his great contributions to the group. Congratulations, Vikas, and all the best for your future!

New publication

Summary of room temperature data on saturation magnetization and coercive field.
Summary of room temperature data on saturation magnetization and coercive field.

A new paper on MnBi thin films has been published in IEEE Transactions on Magnetics by our PhD student Sareh Sabet. Sareh has investigated the growth conditions of MnBi thin films showing a positive temperature coefficient of hysteresis. A magnetic uniaxial anisotropy energy density of ∼1.86•107 erg/cm3 (∼1.86 MJ/m3) was measured by torque magnetometry. Growing LTP MnBi thin films directly from an alloy Mn55Bi45 target is an important step toward facilitating the synthesis of multilayers for spintronics or in an exchange spring magnet configuration.

doi: 10.1109/TMAG.2016.2636817

JU Review Panel of 224 M€-project PANACHE

In April we at ATFT had the pleasure to host the 3rd year review panel of the 224 M€ JU project PANACHE (4 year duration) with more than 20 participants from all over Europe, chasing the next generation of microcontrollers beyond 40 nm FLASH. The overall consortium received very positive feedback from the referees, as well as our contributions to the field of hafnium oxide as active material for eNVM (RRAM).

http://cordis.europa.eu/project/rcn/201978_en.html

Two new publications at ATFT

Magnetic phase diagram of Y-Co thin films.
Magnetic phase diagram of Y-Co thin films.

We congratulate Shalini Sharma and Aldin Radetinac to their first authorship in two new publications of the ATFT group. The first paper deals with the magnetic phase diagram of the Y-Co system describing the transition from soft magnetic behavior to hard magnetic behavior in the quest for future permanent magnetic materials.
doi: 10.1016/j.jmmm.2017.02.020

The second paper describes interface engineered phase boundaries between a highest conducting oxide electrode and a tunable dielectric for application in high-frequency communication devices.
doi:10.1016/j.jcrysgro.2017.02.015