[institut] SCL seminar, cetvrtak 17. oktobar, Ross. McKenzie

[Darko Tanaskovic]

Поштоване колегинице и колеге,

Позивам вас на семинар који ће у четвртак 17. октобра 2013. године у 
11:30 у читаоници Института за физику да одржи Ross H. McKenzie 
(University of Queensland, Brisbane, Australia)
Наслов семинара је:

The transition from a bad metal to a Mott insulator: the case of 
organic charge transfer salts

Organic charge transfer salts, such as kappa-(BEDT-TTF)2Cu(CN)3,
exhibit a subtle competition between bad metal, Fermi liquid,
superconducting, Mott insulator, spin liquid, and antiferromagnetic 
phases [1].
They are a playground to investigate different states of quantum 
matter.

In the metallic phase, with increasing temperature there is a crossover 
from a
Fermi liquid to a bad metal, at a temperature T_coh ~ 30 K.
The signatures of the bad metal are a resistivity of order the 
Mott-Ioffe-Regel limit, thermopower of order k_B/e, and the absence of a 
Drude peak in the
optical conductivity [2].

The simplest possible effective Hamiltonian for these materials
is a one-band Hubbard model on an anisotropic triangular lattice at 
half-filling [1].
At zero-temperature the model exhibits a transition from a Mott 
insulator to a metal as the interaction (U/t) is reduced or the 
frustration (t'/t) is varied.
A Dynamical Mean-Field Theory treatment of the model captures the Fermi 
liquid-bad metal crossover [2], including the observed frequency and 
temperature
dependence of the optical conductivity [3].
A recent study of this Hubbard model, using the finite-temperature 
Lanczos method
(FTLM) [4], showed that near the Mott insulator T_coh ~ t/10, 
consistent with experiment.
The bad metal is characterised by a small charge compressibility,
a large spin susceptibility, and fluctuating local magnetic moments.

[1] B.J. Powell and R.H. McKenzie, Rep. Prog. Phys. 74, 056501 (2011).
[2] J. Merino and R.H. McKenzie, Phys. Rev. B 61, 7996 (2000).
[3] J. Merino et al., Phys. Rev. Lett. 100, 086404 (2008).
[4] J. Kokalj and R.H. McKenzie, Phys. Rev. Lett. 110, 206402 (2013).

Срдачан поздрав,
Дарко Танасковић

-- 
Institute of Physics Belgrade
Pregrevica 118, 11080 Belgrade, Serbia
http://www.ipb.ac.rs/