The year 1930 marked a significant shift as his mother passed away, prompting their entire family's relocation to Gleiwitz amidst an era of economic turmoil and the ascent of Nazism.
As Hitler's ascendancy to power unfurled in Germany, instituting a "numerus clausus" that effectively precluded Jewish individuals from university access, Lewy-Bertaut left for Bordeaux, France.
There, the Rothschild Foundation awarded him a scholarship, facilitating his enrollment at the University of Bordeaux, where Lewy-Bertaut studied chemical engineering, physics, and mathematics.
At the onset of the conflict in 1940, Colonel Faure entrusted him with the military records of a missing soldier, Félix Bertaut, and he adopted this name permanently.
To elude police inspections and evade mandatory labor service, he went to Paris, where he collaborated with Marcel Mathieu at the Laboratoire Central des Poudres.
[9][10] Immediately after his thesis, Lewy-Bertaut started establishing his group at the LEPM that formed the basis of the X-ray department to carry out research in cristallography, along with Francis Forrat and Professor René Pauthenet, distinguished themselves with their work on garnet ferrites, from which the theory of antiferromagnetism and ferrimagnetism was built up.
[5] In 1949, Lewy-Bertaut read a one-page publication[11] by Clifford G. Shull and J. Samuel Smart, which recovered the magnetic structure of MnO from neutron diffraction and validated Louis Néel's work on antiferromagnetism.