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- S=1 spin liquid with fermionic excitations

In the first part of my talk I describe a search for

possible quantum spin liquid ground states for spin S=1 Heisenberg models on

the triangular lattice which was motivated by recent experiments on

Ba3NiSb2O9. We use representation of

spin-1 via three flavors of fermionic spinon operators. The ground state where

one gapless flavor of spinons with a Fermi surface coexists with d+id

topological pairing of the two other flavors can explain available experimental

data. Despite the existence of a Fermi surface, this spin liquid state has

fully gapped bulk spin excitations. This results in a linear in-temperature

specific heat and constant in-plane spin susceptibility, with an unusually high

Wilson ratio. Using variational Monte Carlo technique, we show that proposed

spin liquid ground state is realized in an SU(3)-invariant model with

sufficiently strong ring-exchange terms.

In the second part, I consider the physics of the

magnetic s=1/2 impurity embedded in a S=1 spin liquid, where all three flavors of

spinons have a Fermi surface. The interplay between non-Fermi-liquid behavior

induced by a U(1) gauge field coupled to fermions, and a non-Fermi-liquid fixed

point in the overscreened Kondo problem is studied using double expansion. The

gauge field changes the physical properties of the system at the overscreened

Kondo fixed point. Thus, spin-half impurity in such spin liquid can be used to

probe the presence of fermionic spinons coupled to the gauge field.

References: arXiv:1108.3070, arXiv:1208.3231 and

arXiv:1212.5179

Collection/Series:

Event Type:

Seminar

Scientific Area(s):

Speaker(s):

Event Date:

Thursday, March 28, 2013 - 14:30 to 16:00

Location:

Bob Room

©2012 Perimeter Institute for Theoretical Physics