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UID:UW-Physics-Event-2094
DTSTART:20110131T220000Z
DURATION:PT1H0M0S
DTSTAMP:20240803T101540Z
LAST-MODIFIED:20110127T194327Z
LOCATION:5280 Chamberlin
SUMMARY:Realistic quantum critical points\, Condensed Matter Theory Gr
oup Seminar\, Munehisa Matsumoto\, University of California-Davis
DESCRIPTION:Quantum criticality has been discussed to play a key role
in interesting phenomena in strongly-correlated systems\, such as high
-*T*_{c} superconductivity in cuprates (here *T*_{c} is the superconducting transition temperature)\, recently-dis
covered iron pnictides/chalcogenides\, and heavy-fermion materials. In
the main part of the talk I will show how the magnetic quantum critic
al point (QCP) in heavy-fermion materials can be quantitatively predic
ted by combining electronic-stricture calculations based on local-dens
ity approximation (LDA) and dynamical-mean field theory (DMFT) for the
LDA-derived effective low-energy Hamiltonian. We utilize state-of-the
-art continuous-time quantum Monte Carlo method to solve the impurity
problem in DMFT formulated on the basis of localized f-electrons\, whi
ch enables us to obtain numerically-exact solutions at low temperature
s down to *O*(1) [K] within DMFT. Thus we reach at a good positio
n to address the quantum critical point quantitatively and we find the
followings: 1) striking multiple quantum critical points are found in
a realistic phase diagram for Plutonium-based compounds\, which is at
tributed to the strong-coupling nature of the effective Kondo-lattice
model. PuCoGa_{5}\, with the highest *T*_{c} = 18
.5 [K] among f-electron based materials\, is found be located in the p
roximity to the third QCP [1]. 2) CeCoIn_{5}\, which has the h
ighest *T*_{c} = 2.3 [K] among Cerium-based heavy-fermion
compounds\, its parent material CeIn_{3}\,
\nand its new two-
dimensional (2D) analogue CePt_{2}In_{7} are concentra
ted around a QCP where CeCoIn_{5} is found to be right on top
of QCP. The reason the most 2D one does not come closest to QCP is att
ributed to the subtlety in the competition between the dimensionality
and hybridization effects along the c-axis [2]. In the final part of t
he talk I will discuss the possible subtle nature of what has
\nbeen c
alled QCP\, which still challenges realistic numerics but careful nume
rical analyses of an effective field theory [3] tells us QCP might not
truly be critical. Possible consequence for having the resonating val
ence bond state around what has been QCP [4] is revisited.
\n

\n**
\nReferences
\n**

\n[1] MM\, Q. Yin\, J. Otsuki\, S. Y. Savrasov\
, preprint [arXiv:1101.1582].

\n[2] MM\, M. J. Han\, J. Otsuki\, S
. Y. Savrasov\, Phys. Rev. B 82\, 180515(R) (2010) [arXiv:1004.5457].<
br>
\n[3] A. B. Kuklov\, MM\, N. V. Prokof'ev\, B. V. Svistunov\, M. T
royer\, Phys. Rev. Lett. 101\, 050405 (2008) [arXiv:0805.4334].

\n
[4] P. Coleman and N. Andrei\, J. Phys.: Condens. Matter 1\, 4057 (199
0).
URL:https://www.physics.wisc.edu/events/?id=2094
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