Hendrika Johanna van Leeuwen, known for her contributions to the theory of magnetism

(3 July 1887, The Hague (Netherlands), 26 February 1974, Delf (Netherlands))

Daughter of Professors Pieter Eliza van Leeuwen and Maria Wilhelmina Schepman, she studied secondary education in her hometown, and continued her training in physics at the University of Leiden, under the supervision of Hendrik Antoon Lorentz.

In 1919, he obtained his PhD, whose thesis entitled "Problems of the electronic theory of magnetism" focused on explaining why magnetism is essentially a quantum mechanical effect (a result now known as the Bohr-van Leeuwen theorem). In this respect, Van Leeuwen was unaware of the results presented 8 years earlier by Niels Bohr also in his doctoral thesis.

Hendrika claimed that using the formulae of classical physics and statistical mechanics does not prove the existence of magnetism and that according to these theories, a system in a magnetic field that is in thermal equilibrium cannot have a net magnetic dipole moment.

In addition to his PhD research, he also conducted research on the natural vibrations of hydrogen molecules in the same period.

During and after his PhD research, he taught in secondary schools. In September 1920, he became a practical assistant at the Technische Hogeschool in Delf and, in 1943, received a permanent appointment as senior assistant in theoretical and applied physics. This allowed him to conduct his research on magnetism, including the so-called permeability of ferromagnetic metals such as iron and nickel.

In 1947 she was appointed professor at the Technische Hogeschool in Delft, becoming the first woman professor at this institution.

Like other women during this period, she was torn between her ambition for science and social pressure to marry. She decided to resist this pressure and dedicate herself to her dream. After her retirement in 1952 she gave lectures on ferromagnetism and special relativity.

Hendrika Johanna van Leeuwen died in Delft at the age of 86.