Upcoming ICTP/SISSA Stat.Physics Seminar

[Statistical Physics]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR


Monday, 21 July 2014 - 16:00 hrs.*
*

ICTP Leonardo Building, Luigi Stasi Lecture Room, first floor


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Speaker: Giacomo MARMORINI  (RIKEN

Title:     New Results for Quantum Antiferromagnets in High Magnetic Fields


Abstract:
Frustrated antiferromagnets are a very rich class of physical systems, 
in which various
new phases of matter are expected to be realized. From a theoretical 
point of view,
however, they present challenging difficulties and typically defy a full 
quantum
treatment. A possible strategy is to restrict oneself to a specific 
region of the parameter
space, namely the one of high applied magnetic field, where the problem 
can be
mapped to a dilute Bose gas of magnons. In this way we can provide 
benchmarks for
the latest numerical approaches, such as in the case of the prototypical 
spin-1/2
XXZ model on the triangular lattice [1]. In more complicated models with 
competing
exchange interactions, we find new types of magnetic order, such as a 
double-q state
with striped chiral order [2]. Several problems remain open in this 
field-theoretical
approach, in particular three-magnon and four-magnon scattering 
amplitudes, which
relate to a recently discovered magnetic "0-pi" phase transition and to 
the stability
of the spin nematic phase respectively.


[1] D. Yamamoto, G. Marmorini and I. Danshita, Phys. Rev. Lett. 112
(2014) 127203.
[2] G. Marmorini and T. Momoi, Phys. Rev. B 89, 134425 (2014).