Q: What do you say at a dinner party when someone says “and what do you do?”

I’m a physicist and I look for novel effects that utilize the spin of the electron and can be used in electronic devices. Besides being a fascinating field of research, this approach enables the conception of advanced, super-fast microelectronic components that consume less energy.

    Q: Did you ever have a eureka moment, when you thought, “this is the subject I want to study”?

When I was an undergrad in engineering, I had the chance to attend a conference on nanotechnology in Toulouse, France. There, I listened to a talk about manipulating the spin of an electron with light and making devices based on the manipulated spin. I had only just learned what electron spin was and it really blew my mind that such a fundamental quantum property could actually be used in devices. That’s when I thought, “that’s what I want to do.”

    Q: What made you choose an academic career ? Is there any special reason for that?

Like many kids, I was inspired by Newton’s, Einstein’s and Heisenberg’s adventures. But frankly, I never seriously considered doing research before I started my PhD. While in grad school, I truly felt like I was Indiana Jones, exploring the jungle of physics. I was constantly learning, confronting difficult problems and, sometimes, even finding solutions. I was also thrilled about traveling to conferences and debating these problems and solutions with physicists from around the world. Overall, it is quite a demanding career, as you need to continuously challenge yourself, provoke your intellect, accept criticism and relentlessly propose new, creative ideas. But I find this quest absolutely thrilling. Playing with the laws of nature to discover new phenomena is simply awesome.

    Q: You are one of the pioneers at KAUST. Why did you choose KAUST?

I was doing my postdoc in Tucson, Arizona when a friend told me about this new university in Saudi Arabia. At that time, my wife was pregnant with our first child and I was thinking about my next move. We together found the KAUST project to be so exceptional that we decided that we had to give it a try. A combination of thought-provoking factors led us to decide to join the KAUST journey. First, this university was being built out of the desert with a mission to contribute to the scientific and academic development of Saudi Arabia and the Middle East region. Second, it was the first co-ed university in the country, which we found inspiring. Third, KAUST offered me amazing opportunities to start my own group. As a young theorist, such opportunities would enable me to create my own research group, and tackle a broad range of topics while actively contributing to the progress of my field. The academic environment impressed me a lot, with faculty members coming from prestigious places such as Stanford, Berkeley, ETH and UT Austin. Finally, KAUST was planning to be truly international. There are more than 90 nationalities on campus; our kids have daily opportunities to have incredible experiences with people from different cultures, with different ways of thinking. This is something I value most.

    Q: What do you like best about teaching at KAUST? What are your favorite topics to teach? Why?

Research is about pushing the frontiers of knowledge and, as such, teaching and transmitting this knowledge is inherent to the progress of research. This is why I consider teaching and mentoring as essential to my success as a researcher. The courses I really enjoy teaching concern quantum mechanics, quantum transport and spintronics. They give me opportunities to talk about mind-blowing effects that at first sound counterintuitive, but make sense once you completely change your perspective. These are also the kind of classes in which students can get really enthusiastic and run the extra mile on their own.

    Q: You have a reputation for presenting complex topics in an accessible way. What are your strategies for doing that?

I believe that researchers have a responsibility to the broad public to make their research understandable. This may not be easy in every field, but it turns out that in condensed matter physics, most physical phenomena can find their counterparts in the real, macroscopic world. I really love to establish such connections and try to explain advanced concepts in terms of hand-waving arguments or everyday experience. When they start having a feeling about what is going on, people start to understand the value of the research and get excited about it.

    Q: What is the strength of your research group?

In my view, we have two strengths. First, we are able to tackle spintronics and condensed matter physics from the perspectives of magnetization dynamics to spin transport to materials modeling. I am constantly trying to push our limits and acquire new techniques to broaden the scope of our scientific capacities. Second, we have strong connections with experimentalists. Initially trained as an experimentalist myself, I believe that our models and theories are meant to be experimentally observed. This is why we systematically try to consider the experimental relevance of our models. We currently have active collaborations with experimental groups in Singapore, France, Germany, the US, and Japan. In turn, our research benefits from input from our collaborators.

    Q: Could you please identify a couple areas of research in of your group that are especially important?

The two most important and successful topics we are currently working on are “antiferromagnetic spintronics” and “spin-orbitronics”​. The former intends to use antiferromagnets, rather than ferromagnets, as active elements in spin-based devices. The second concerns the physics of spin-orbit coupling, particularly the conversion between spin and charge currents, and the onset and electrical manipulation of chiral magnetic structures. We have recently published several reviews on both topics, including in Review of Modern Physics, Nature Materials and Nature Physics [2014​, 2018​].

    Q: What are your group’s goals in the coming 5-10 years?

The grail is to make a transformative contribution to the field, something that can change our way of looking at things and open unforeseen avenues. In my early career, I was lucky enough to be associated with the onset of “spin-orbit torque”, a field of research that aims at utilizing spin-orbit coupling to electrically control the magnetization of ferro or antiferromagnets. I hope to make a similar kind of transformative discovery in the coming years. As a possible route, I envision transferring the knowledge acquired in spin-orbitronics to novel systems, such as strongly correlated systems, curved materials, superconductors, frustrated magnets and magnetic monopoles. Although such materials are quite exotic, I am confident that at least some of them can be made useful if approached from the right perspective.

    Q: What is the best thing about being a theoretical physicist?

What is truly exciting is the fact that the research horizon is completely wide open to a theoretical physicist. We can make any type of "experiments" we can imagine; we are limited only by our own creativity (and computational resources, which are continuously improving).

    Q: Where does spintronics stand today and what is its future?

Spintronics is currently developing along several directions. Let me just name a few of the most active ones:

- Spin-orbitronics and chiral magnetism: the exploitation of materials with strong spin-orbit coupling (transition metals, topological materials), the generation of large spin currents, the control of spin-orbit torque, the study and manipulation of magnetic skyrmions.

- Antiferromagnetic spintronics: the manipulation and detection of antiferromagnets and exploration of their potential as active elements in spin-based devices.

- Spincaloritronics, magnonics and insulatronics: the generation and detection of spin currents using thermal gradients, the observation of spin currents mediated by magnons in magnetic insulators and the investigation of exotic magnetic excitation, such as magnonic Bose-Einstein condensate or spin superfluidity.

- Ultrafast dynamics and THz spintronics: the control of magnetization on the femtosecond scale using laser pulses along with the generation of THz signals using superdiffusive currents.

We should keep in mind that these research directions have been nurtured by the already established success of spintronics applications, from sensors to magnetic read-heads in hard drives and magnetic random access memories. On-going research therefore aims at proposing new mechanisms to expand the scope of possible applications.

Among the future directions, I mention the development of neuromorphic computing using spintronics systems, quantum computing using spin or spin-orbit qubits and non-abelian topological computing using Majorana fermions. These directions could massively benefit from spintronics concepts. In addition, the emergence of 2D materials is expected to enable the expansion of spintronics in "Flatland" and the realization of ultracompact spin devices. I believe these areas will grow tremendously fast in the coming decade.

Considering this impressive progress, it is now time to take spintronics out of its enclosure and make it part of the common knowledge of condensed matter physicists. A few initiatives have been taken along this line, such as at the MRAM School headed by Dr. Bernard Dieny at Minatec in Grenoble, France. I hope that my group can also contribute to this effort.