Placement Information

Year you started your placement
2018

Placement period
May – August, September – December

Supervisor’s name
Simone Altendorf

Project Details

Overview
Topological insulators represent a class of materials which are simultaneously metallic at the surface and insulating within the bulk. Interfacing a topological insulator with a magnetic material can lead to changes in the electronic structure like gapping of the topological surface states which enable the surface conduction of the material. The goal of the project was to find suitable magnetic materials to deposit on top of the topological insulator Bismuth Telluride (Bi2Te3) so as to study these changes and the topological insulator-magnet heterostructure and interface.

Project objectives
The project focused on interfacing Bismuth Telluride with magnetic insulators Magnetite (Fe3O4) and Europium (II) Oxide (EuO) to gap the surface states and study the changes in electronic structure and transport properties. One of the prerequisites for the success of interfacing any magnetic material with Bismuth Telluride for our purposes is the lack of significant chemical reaction at the interface, thus the project has two key components: 1) ensuring minimal reaction at the interface, and 2) characterizing changes in electronic structure and transport properties of the resultant heterostructure.

My main focus was on growing the films and observing whether or not a chemical interaction occurred at the interface and the overall quality of the resultant films. To do this we use Molecular Beam Epitaxy (MBE) under Ultra-High Vacuum (UHV) conditions to achieve epitaxial (crystalline layered) growth of our films. We then use various spectroscopic techniques to characterize the crystalline structure and quality (RHEED, LEED), chemical composition (XPS), and electronic band structure (ARPES) of the films.

Research outcomes
We found that we were able to successfully interface Magnetite with Bismuth Telluride but not Europium (II) Oxide, which appeared to have a significant chemical reaction at the interface. The observed changes in the transport properties of the Bismuth Telluride – Magnetite heterostructure were as predicted by theory for Magnetite grown in the (100) direction, and further work is needed to observe the results from Magnetite grown in the (111) direction.

Project status
Completed

CariadKnight_2018_Presentation

My Co-op Experience at MPI/ UTokyo

Why did you apply for this placement?
I applied for this placement because I am very interested in doing graduate studies abroad, particularly in Germany since the country has such a strong and vast scientific community. I also really wanted to do a Co-op term that was outside of Canada for the learning experience and opportunities that living in another country provides. I was specifically excited at the opportunity to apply for this job with the Max Planck Institute because I was aware of their reputation for doing high-caliber and cutting edge research and thought this would be a good learning environment. I wanted to observe what qualities the researchers and graduate students at the institute possessed to try and foster them in myself and become a better scientist and a more desirable graduate school applicant. And of course I was very interested in the specific research project topic!

What recommendations do you have for students who wish to participate in this exchange program?

Try to be realistic with yourself about what you want to get out of the program and what you can achieve given your time frame, project specifics, and what experience and background knowledge you bring with you. It’s ok if you don’t understand or learn everything about the theory behind the project or the entire big picture before you jump into the more hands-on portion. In order to be successful in the placement you usually don’t have to understand absolutely everything about the topic and it’s background – often times people are taking 3-4 years to do a PhD on the topic that you will only be able to scratch the surface of in 8 months!

The placement is very autonomous, so one must be very mature, self-motivated, and enthusiastic about the topic. You should be capable to independently learn about the topic and project and good at governing your own time and setting your own goals. Because of this I also think it’s vitally important that you seek clarity in your role in the group, your individual goals, and project breakdown immediately if it is unclear to you in any way. I also think because of the high level of independence that is expected it is very beneficial if this is not your first in-depth lab or research experience.

I would also advice students to take advantage of the various opportunities that the institutes offer. Our Max Planck in Dresden offers many guest lecturers and seminars which is a great way to gain exposure to areas of academic research from around the globe in topics that you wouldn’t otherwise be exposed to. There are also so many different fields of research taking place under the institutes roof, so if you have some down time in your research I think it’s worth it to shadow or volunteer with other groups and projects. While I was at MPI CPfS I took part in the research that another group was doing in Japan and got to experience a completely different topic than the one I was placed on as well as a totally different country!

Tell us about your travels and cultural experiences
The travel and cultural experiences were a huge part of this placement for me and probably make up some of my most fond memories of the exchange. Having never lived abroad or really traveled outside of Canada my experiences of living in and traveling to countries where I didn't speak the language were really eye-opening and valuable to me. I think learning to be self-reliant (not just on a smart phone) and to navigate unknown places and customs is a very useful skill.

I usually traveled on weekends, Dresden is near to the Czech Republic (take the train to Prague!) and Poland and I would highly suggest both of these for weekend trips. Dresden is also about a 3 hr bus ride to Berlin, where many cheaper flights operate, so I would often fly from Berlin rather than Dresden – just make sure you coordinate your travel plans with what's happening in the lab that day! I would highly suggest trying to take part in the customs of the places you travel to, knowing a few key words or phrases in the common language (thank you, excuse me, sorry, can you please help me in English), and eating the customary foods. And really do take advantage of how easy it is to travel once you're in Europe since it really can be a life changing experience, especially when done alone!

I would also suggest that, if you're in Dresden, you take full advantage of the arts scene that the city has. Dresden has a very famous opera house (the SemperOper) and they sell tickets to students 30 minutes before the show for only 10 Euros, so I was able to see many world class operas and ballets for very cheap! They also have a museum pass you can get for fairly cheap (Staatliche Kunstsammlungen Dresden or Dresden State Art Collections) which gives access to 15 different museums and is a fantastic deal!

Wroclaw, Poland
Sitges, Spain
Paris, France