Bloch remained in European academia, working on
superconductivity with
Wolfgang Pauli in Zurich; with
Hans Kramers and
Adriaan Fokker in the Netherlands; with Heisenberg on
ferromagnetism, where he developed a description of boundaries between
magnetic domains, now known as
Bloch walls, and theoretically proposed a concept of
spin waves, excitations of
magnetic structure; with
Niels Bohr in Copenhagen, where he worked on a theoretical description of the stopping of
charged particles traveling through matter; and with
Enrico Fermi in Rome. In 1934, the chairman of the Physics Department of
Stanford University invited Bloch to join the faculty. After the war, Bloch concentrated on investigations into nuclear induction and
nuclear magnetic resonance, which are the underlying principles of
MRI. In 1946, he proposed the
Bloch equations, which determine the time evolution of nuclear magnetization. Along with
Edward Purcell, Bloch was awarded the
Nobel Prize in Physics in 1952 for his work on nuclear magnetic induction. When
CERN was being set up in the early 1950s, its founders were searching for someone of stature and international prestige to head the fledgling international laboratory, and in 1954 Professor Bloch became CERN's first director-general, at the time when construction was getting under way on the present
Meyrin site and plans for the first machines were being drawn up. After leaving CERN, Bloch returned to Stanford University, where in 1961 he was made Max Stein Professor of Physics. He retired from Stanford in 1971. == Family ==