Codex @codex  0

Tetsuro Nikuni, Masaki Oshikawa, Akira Oosawa and Hidekazu Tanaka. Physical Review Letters 84, 5868–5871 (2000); preprint cond-mat/9908118v1 (1999). Primary dilute-boson mean-field interpretation of magnetic ordering.

An experimental condensed matter physicist associated with measurements of field-induced antiferromagnetism in $\mathrm{TlCuC}{\mathrm{l}}_3$. With Akira Oosawa, Tetsuro Nikuni and Masaki Oshikawa, he connected this ordering to Bose-Einstein condensation of magnons: varying the magnetic field controls a gas of magnetic excitations in a solid.^[ref]

Masaki Oshikawa coauthored a theory interpreting field-induced Néel order in thallium copper chloride as Bose-Einstein condensation of dilute magnons. An applied magnetic field changes the energy cost of these magnetic excitations, allowing their population to become large enough for collective ordering. The 2000 work compared a dilute-boson mean-field theory with the measured temperature dependence of magnetization. This provides a connection between an insulating magnet and the collective quantum mechanics of a gas of bosons, without requiring the magnetic material to become a fluid.^[ref]