Research: Phase transitions with fractionalized particles

When a frustrated magnet is cooled down to the lowest temperatures, novel particles can emerge, which are fundamentally different from the particles that the material is made of. Sometimes, these emergent particles can be understood as fractions of the original constituents. Our calculations show that such a situation has crucial implications when a frustrated antiferromagnet is driven near a paramagnetic phase. We predict an exotic quantum critical behavior that reflects the phenomenon of fractionalization. Our models realize a new class of fractionalized quantum phase transitions characterized by fluctuations of massless Majorana fermions. This may be observable in frustrated magnets with spin and orbital degrees of freedom.

U. F. P. Seifert, X.-Y. Dong, S. Chulliparambil, M. Vojta, H.-H. Tu, L. Janssen,
Fractionalized fermionic quantum criticality in spin-orbital Mott insulators,
Phys. Rev. Lett. 125, 257202 (2020) (arXiv)