Dr Buyisiwe Sondezi, a student at the University of Johannesburg (UJ), is the first woman in Africa to be awarded a doctoral degree in experimental physics of highly correlated matter.
Sondezi graduated as a Doctor of Physics at UJ in September this year. The title of her thesis was “The physical properties of ferromagnetic CeTX compounds, where T is Copper and Gold and X is Silicon and Germanium”.
In particular, Sondezi worked on quantum criticality in matter, which is a quantum mechanical property that characterizes the birth of collective behaviour in matter at extremely low temperatures, according to Professor André Strydom, Sondezi’s doctoral thesis supervisor from the Department of Physics.
Sondezi’s research drawing global attention
“The theme of Sondezi’s research for her PhD and her contributions in published papers are very topical. This research direction is drawing a great deal of attention worldwide, because it is widely recognised as a frontier in the Physics of highly correlated matter,” he says, adding that Sondezi is one of very few women in Africa to employ the technique of inelastic neutron scattering as part of the research in her PhD.
“In particular, Dr Sondezi worked on quantum criticality in matter, which is a quantum mechanical property that characterizes the birth of collective behaviour in matter at extremely low temperatures.”
Sondezi’s doctoral thesis describes behaviour contrary to established laws and paradigms of Physics. Strydom says he proposed that Sondezi investigate the behaviour of a highly correlated spin system by way of the three magnetic compounds named in the title of her thesis. In essence, her thesis poses the question: “Is it possible to induce fluctuations in a lattice when it undergoes a phase transition into a highly ordered ferromagnetic spin system by applying a magnetic field orthogonal to the direction of the spin arrangement?”.
Sondezi’s experimental research investigating this question opened up even more perplexing questions. The project is ongoing and with collaborators in Europe now also involved, there is a fascinating journey of search and discovery that lies ahead, according to Strydom.
Venturing into quantum physics
During her PhD studies, Sondezi says she found quantum “criticality interesting, although it was extremely difficult”. “Nevertheless, I did it to know what is really happening. In experimental Physics, the only interpretation possible is based on the data you get from the machine,” she says.
There was also another challenge that drew Sondezi to venture into quantum physics. She says there are very few people who are in this field. “That drove me into embarking on this, although that had its own difficulties. As I went through my PhD, there were cases where fundamental expertise were needed and could not be easily obtained from other colleagues in the field of magnetism. In cases of this kind of speciality (highly correlated condensed matter) in the absence of Prof Strydom due to conferences and research visits, finding someone to assist me was difficult,” she says.
Sondezi’s journey to become a top physicist started way back at a rural school near Newcastle, KwaZulu-Natal. The school had no laboratory and learners had to rely “on what the text book said”. “I had to picture how things are, because the school had no lab. I was just told if you mix ‘one’ and ‘two’ you get a ‘three’,” says Sondezi.
After high school, Sondezi enrolled at Vista University in Soweto, which is now part of the University of Johannesburg, graduating with a BSc with major in physics, chemistry and statistics. Deciding to further her studies, Sondezi went to do her honours degree in physics at the same institution.
“My first-year Physics lecturer was Prof Hartmut Winkler, who is the Head of Department at Physics now. I saw him as a person who knew what he was doing. He explained things so well and made it clear. I think I first fell in love with physics that year,” she says.
After her honours, she went to do her Masters Degree in Physics, researching properties of solar cells, and started a PhD in the same direction. However, the experimental Physics of highly correlated matter beckoned. She switched to her eventual PhD topic with Strydom and started again in 2007.
Sondezi a highly impressive student
Strydom was highly impressed by Sondezi’s perseverance and dedication. He says Sondezi is a mild, gentle and has a persuasive character.
“I have witnessed what difficult times she had come through. When someone wants something with so much passion and fervour, and gets through all of the obstacles and the difficulties in life to achieve what she wants to achieve, then we have a responsibility to embrace the student’s aspirations and to give her every opportunity to help realize her goals in life.
“I have learnt from the example set by Buyi just as much as she has learnt from working as a Physics researcher in our group,” says Strydom.
While working on her PhD, Sondezi co-authored four academic papers published in prestigious Physics journals. In addition, she has collaborated with globally known researchers at the ISIS facility in England.
With her PhD in the bag, Sondezi is keen to explore properties of other compounds, or examine more deeply the ones she has studied already.
“There is still much more to learn in this field. I think it’s only when you finish your PhD, that you really know that you don’t know much,” she says.
Having a doctorate comes with its own perks. Sondezi is now an academic member of the highly regarded Physics department at the University of Johannesburg, where she engages with numerous top physicists working in cutting edge research in diverse topics such as Condensed Matter Physics, High-Energy Physics and Astrophysics.
Strydom is full of praise for Sondezi. “Nowadays I call her a collaborator. She’s fully qualified, she is competent and skilled to conduct difficult laboratory experiments and she knows what research is about. Our collaborators and research partners elsewhere in the world recognize Buyi as a researcher and a contributor in our sphere of research. It is hard work and perseverance that has gained her acceptance in the world of Physics research,” he says.
By: Ndaba Dlamini