Fractional Excitations in a Spin-Orbital Chain

Datum

12.06.2014

Zeit

13:30 - 14:30

Sprecher

Dr. Cheng-Chien Chen

Zugehörigkeit

Argonne National Laboratory

Sprache

en

Hauptthema

Materialien

Andere Themen

Materialien, Physik

Host

Grit Rötzer

Beschreibung

Recent measurements by resonant inelastic x-ray scattering have reported a spin-orbital separation in various quasi-one-dimensional copper-oxide materials. Under a large crystal field, a spin or orbital flip was suggested to separate into two independent spinon and orbiton, carrying respectively only the spin and orbital quantum number. Here we show that collective excitations in a spin-orbital chain do not separate but always entangle. Irrespective of the crystal field strength, these excitations can be universally described by fractionalized constrained fermions, carrying simultaneously spin and orbital quantum numbers. This persistent fractionalization contrasts strikingly with the case of a pure spin chain, where fractionalized spinons are confined as magnons of integral quantum numbers in a strong magnetic field. The result also shows that the recently reported spin-orbital separation occurs solely due to a particular choice of basis, which is allowed only when crystal fields fully polarize the orbital variables. .

Links

• Seminars at the IFW

Letztmalig verändert: 12.06.2014, 09:58:52